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terms the likelihood of finding life at each specific celestial body, as it is known which features are beneficial and harmful for life. Astronomy and telescopes also improved to the point exoplanets can be confirmed and even studied, increasing the number of search places. Life may still exist elsewhere in the Solar System in unicellular form, but the advances in spacecraft allow to send robots to study samples in situ, with tools of growing complexity and reliability. Although no extraterrestrial life has been found and life may still be just a rarity from Earth, there are scientific reasons to suspect that it can exist elsewhere, and technological advances that may detect it if it does.
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2237:. This theory provided the mathematics that explains the motions of all things in the universe, including planetary orbits. By this point, the geocentric model was definitely discarded. By this time, the use of the scientific method had become a standard, and new discoveries were expected to provide evidence and rigorous mathematical explanations. Science also took a deeper interest in the mechanics of natural phenomena, trying to explain not just the way nature works but also the reasons for working that way.
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1148:. So far no alternative process to achieve such a result has been conceived, even if hypothetical. Evolution requires life to be divided into individual organisms, and no alternative organisation has been satisfactorily proposed either. At the basic level, membranes define the limit of a cell, between it and its environment, while remaining partially open to exchange energy and resources with it.
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1196:, as an ecosystem sustained by black smokers or hydrothermal vents would have less energy available than those sustained by a star's light and heat, and so its lifeforms would not grow beyond a certain complexity. There is also research in assessing the capacity of life for developing intelligence. It has been suggested that this capacity arises with the number of potential
1416:. With the study of Earth's life, the only known form of life, astrobiology seeks to study how life starts and evolves and the requirements for its continuous existence. This helps to determine what to look for when searching for life in other celestial bodies. This is a complex area of study, and uses the combined perspectives of several scientific disciplines, such as
1128:. Extraterrestrial life may still be stuck using RNA, or evolve into other configurations. It is unclear if our biochemistry is the most efficient one that could be generated, or which elements would follow a similar pattern. However, it is likely that, even if cells had a different composition to those from Earth, they would still have a
1036:, or a close analog, such an element should be able to bind its atoms with many others, creating complex and stable molecules. It should be able to create at least three covalent bonds; two for making long strings and at least a third to add new links and allow for diverse information. Only nine elements meet this requirement:
1314:, the surface is the hottest in the Solar System, sulfuric acid clouds, all surface liquid water is lost, and it has a thick carbon-dioxide atmosphere with huge pressure. Comparing both helps to understand the precise differences that lead to beneficial or harmful conditions for life. And despite the conditions against
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with different biochemistry, but the cold temperatures would make such chemistry take place at a very slow pace. Water is rock-solid on the surface, but Titan does have a subsurface water ocean like several other moons. However, it is of such a great depth that it would be very difficult to access it
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paired with extreme temperatures, lack of water, and much more that can lead to conditions that don't seem to favor the creation or maintenance of extraterrestrial life. However, there has been much historical evidence that some of the earliest and most basic forms of life on Earth originated in some
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to local characteristics of the planet, and that it is unlikely that all such requirements are simultaneously met by another planet. The proponents of this hypothesis consider that very little evidence suggests the existence of extraterrestrial life, and that at this point it is just a desired result
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is complex and defined by several factors. Being in the habitable zone is not enough for a planet to be habitable, not even to actually have such liquid water. Venus is located in the habitable zone of the Solar System but does not have liquid water because of the conditions of its atmosphere. Jovian
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that would eventually create rocky planets like Earth. Although Earth was in a molten state after its birth and may have burned any organics that fell in it, it would have been more receptive once it cooled down. Once the right conditions on Earth were met, life started by a chemical process known as
208:
has communicated scientific ideas, imagined a range of possibilities, and influenced public interest in and perspectives on extraterrestrial life. One shared space is the debate over the wisdom of attempting communication with extraterrestrial intelligence. Some encourage aggressive methods to try to
5133:
Klein, Harold P.; Levin, Gilbert V.; Levin, Gilbert V.; Oyama, Vance I.; Lederberg, Joshua; Rich, Alexander; Hubbard, Jerry S.; Hobby, George L.; Straat, Patricia A.; Berdahl, Bonnie J.; Carle, Glenn C.; Brown, Frederick S.; Johnson, Richard D. (1 October 1976). "The Viking
Biological Investigation:
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thought that the processes that created the world, its animals and plants should have created other worlds elsewhere, along with their own animals and plants. Aristotle thought instead that all the earth element naturally fell towards the center of the universe, and that would made it impossible for
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A group of scientists at
Cornell University started a catalog of microorganisms, with the way each one reacts to sunlight. The goal is to help with the search for similar organisms in exoplanets, as the starlight reflected by planets rich in such organisms would have a specific spectrum, unlike that
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and ecosystems hosted by extraterrestrial bodies, extraterrestrial life can seem more speculation than reality, due to the harsh conditions and disparate chemical composition of the atmospheres, when compared to the life-abundant Earth. However, there are many extreme and chemically harsh ecosystems
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About 1/4 of stars are GK Sun-like stars. The number of stars in the galaxy is not accurately known, but assuming 200 billion stars in total, the Milky Way would have about 50 billion Sun-like (GK) stars, of which about 1 in 5 (22%) or 11 billion would be Earth-sized in the habitable
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is of interest to astrobiology, not because of the origin of life on Earth, but for the chances of a similar process taking place in other celestial bodies. Many aspects of life, from its definition to its chemistry, are analyzed as either likely to be similar in all forms of life across the cosmos
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influenced the popular perception over the real-life topic, making people eager to jump to conclusions about the discovery of aliens. Science marched at a slower pace, some discoveries fueled expectations and others dashed excessive hopes. For example, with the advent of telescopes, most structures
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There was very little actual discussion about extraterrestrial life before this point, as the
Aristotlean ideas remained influential while geocentrism was still accepted. When it was finally proved wrong, it not only meant that Earth was not the center of the universe, but also that the lights seen
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for this, as it can manage large amounts of data and is devoid of biases and preconceptions. Besides, even if there is an advanced extraterrestrial civilization, there is no guarantee that it is transmitting radio communications in the direction of Earth. The length of time required for a signal to
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processes which allow organisms to utilize energy through reduced chemical compounds that fix carbon. In return, these reactions will allow for organisms to live in relatively low oxygenated environments while maintaining enough energy to support themselves. The early Earth environment was reducing
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and meeting the much colder oceanic water. Even in today's world, there can be a diverse population of bacteria found inhabiting the area surrounding these hydrothermal vents which can suggest that some form of life can be supported even in the harshest of environments like the other planets in the
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it is carbon and in the atmosphere, it is carbon and nitrogen. Silicon, however, has disadvantages over carbon. The molecules formed with silicon atoms are less stable, and more vulnerable to acids, oxygen, and light. An ecosystem of silicon-based lifeforms would require very low temperatures, high
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Tenenbaum, P.; Jenkins, J. M.; Seader, S.; Burke, C. J.; Christiansen, J. L.; Rowe, J. F.; Caldwell, D. A.; Clarke, B. D.; Li, J.; Quintana, E. V.; Smith, J. C.; Thompson, S. E.; Twicken, J. D.; Borucki, W. J.; Batalha, N. M.; Cote, M. T.; Haas, M. R.; Hunter, R. C.; Sanderfer, D. T.; Girouard, F.
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has an office for the study of "non-identified aero spatial phenomena". The agency is maintaining a publicly accessible database of such phenomena, with over 1600 detailed entries. According to the head of the office, the vast majority of entries have a mundane explanation; but for 25% of entries,
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was completed. Under this new understanding, the notion of extraterrestrial life became feasible: if Earth is but just a planet orbiting around a star, there may be planets similar to Earth elsewhere. The astronomical study of distant bodies also proved that physical laws are the same elsewhere in
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process can start within a gaseous or solid medium: the atom speeds, either too fast or too slow, make it difficult for specific ones to meet and start chemical reactions. A liquid medium also allows the transport of nutrients and substances required for metabolism. Sufficient quantities of carbon
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Many scientists are optimistic about the chances of finding alien life. In the words of SETI's Frank Drake, "All we know for sure is that the sky is not littered with powerful microwave transmitters". Drake noted that it is entirely possible that advanced technology results in communication being
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yet and based their ideas on pure thought and speculation, but they developed precursor ideas to it, such as that explanations had to be discarded if they contradict observable facts. The discussions of those Greek scholars established many of the pillars that would eventually lead to the idea of
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proposes that a civilization may eventually start consuming energy directly from its local star. This would require giant structures built next to it, called Dyson spheres. Those speculative structures would cause an excess infrared radiation, that telescopes may notice. The infrared radiation is
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Mars landers reported gas emissions from heated
Martian soil samples that some scientists argue are consistent with the presence of living microorganisms. Lack of corroborating evidence from other experiments on the same samples suggests that a non-biological reaction is a more likely hypothesis.
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authors created bizarre aliens, clearly distinct from humans. A usual way to do that was to add body features from other animals, such as insects or octopuses. Costuming and special effects feasibility alongside budget considerations forced films and TV series to tone down the fantasy, but these
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By the 21st century, it was accepted that multicellular life in the Solar System can only exist on Earth, but the interest in extraterrestrial life increased regardless. This is a result of the advances in several sciences. The knowledge of planetary habitability allows to consider on scientific
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demonstrated that even in modern times, humanity could be profoundly influenced in its search for extraterrestrial life by subtle and comforting archetypal ideas which are largely derived from firmly held religious, philosophical and existential belief systems. On a positive note, however, Beck
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engaged in medieval thought experiments that postulated the plurality of worlds. However, those ideas about other worlds were different from the current knowledge about the structure of the universe, and did not postulate the existence of planetary systems other than the Solar System. When those
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and beyond, the atmospheres are most likely reducing or with very low oxygen levels, especially when compared with Earth's atmosphere. If there were the necessary elements and ions on these planets, the same carbon fixing, reduced chemical compounds occurring around hydrothermal vents could also
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stars with planets orbiting them in the observable universe. Even if it is assumed that only one out of a billion of these stars has planets supporting life, there would be some 6.25 billion life-supporting planetary systems in the observable universe. A 2013 study based on results from the
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have an "Earth-sized" planet in the habitable zone, with the nearest expected to be within 12 light-years distance from Earth. Assuming 200 billion stars in the Milky Way, that would be 11 billion potentially habitable Earth-sized planets in the Milky Way, rising to 40 billion if
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also have subsurface oceans, but life is less likely in them because water is sandwiched between layers of solid ice. Europa would have contact between the ocean and the rocky surface, which helps the chemical reactions. It may be difficult to dig so deep in order to study those oceans, though.
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or "Goldilocks zone", where water may be at the right temperature to exist in liquid form at a planetary surface. This area is neither too close to the star, where water would become steam, nor too far away, where water would be frozen as a rock. However, although useful as an approximation,
1576:. Adenine and guanine are components of DNA, and the others are used in other biological processes. The studies ruled out pollution of the meteorites on Earth, as those components would not be freely available the way they were found in the samples. This discovery suggests that several
1600:. It is still unclear if those compounds played a role in the creation of life on Earth, but Sun Kwok, of the University of Hong Kong, thinks so. "If this is the case, life on Earth may have had an easier time getting started as these organics can serve as basic ingredients for life."
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may have been possible. But when the planetary core ceased to generate a magnetic field, solar winds removed the atmosphere and the planet became vulnerable to solar radiation. Ancient lifeforms may still have left fossilised remains, and microbes may still survive deep underground.
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Cosmic pluralism, the plurality of worlds, or simply pluralism, describes the philosophical belief in numerous "worlds" in addition to Earth, which might harbor extraterrestrial life. The earliest recorded assertion of extraterrestrial human life is found in ancient scriptures of
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or acidic hot springs as some of the first places that life could have originated on Earth. These environments can be considered extreme when compared to the typical ecosystems that the majority of life on Earth now inhabit, as hydrothermal vents are scorching hot due to the
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or only native to Earth. Astrobiology, however, remains constrained by the current lack of extraterrestrial lifeforms to study, as all life on Earth comes from the same ancestor, and it is hard to infer general characteristics from a group with a single example to analyse.
411:. When scientists talk about extraterrestrial life, they consider all those types. Although it is possible that extraterrestrial life may have other configurations, scientists use the hierarchy of lifeforms from Earth for simplicity, as it is the only one known to exist.
511:. As a result, it is inferred that life in other celestial bodies may be equally adaptive. However, the origin of life is unrelated to its ease of adaptation, and may have stricter requirements. A planet or moon may not have any life on it, even if it was habitable.
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as well. The challenge for this search is that there are natural sources of such signals as well, such as gamma-ray bursts and supernovae, and the difference between a natural signal and an artificial one would be in its specific patterns. Astronomers intend to use
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provided close images of Mars, which debunked forever the idea of the existence of
Martians and decreased the previous expectations of finding alien life in general. The end of the spontaneous generation belief forced to investigate the origin of life. Although
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The Solar System has a wide variety of planets, dwarf planets, and moons, and each one is studied for its potential to host life. Each one has its own specific conditions that may benefit or harm life. So far, the only lifeforms found are those from Earth. No
4043:
Swift, Jonathan J.; Johnson, John Asher; Morton, Timothy D.; Crepp, Justin R.; Montet, Benjamin T.; et al. (January 2013). "Characterizing the Cool KOIs. IV. Kepler-32 as a
Prototype for the Formation of Compact Planetary Systems throughout the Galaxy".
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may be another technosignature, as multiple lights on the night side of a rocky planet can be a sign of advanced technological development. However, modern telescopes are not strong enough to study exoplanets with the required level of detail to perceive it.
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compiled information about it, part of which was translated by
Islamic scholars and thus survived the end of the Library. Baghdad combined the knowledge of the Greeks, the Indians, the Chinese and its own scholars, and the knowledge expanded through the
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by proposing that the planets revolve around the sun rather than Earth. His proposal had little acceptance at first because, as he kept the assumption that orbits were perfect circles, his model led to as many inaccuracies as the geocentric one.
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The extrasolar planets so far discovered range in size from that of terrestrial planets similar to Earth's size to that of gas giants larger than
Jupiter. The number of observed exoplanets is expected to increase greatly in the coming years. The
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that considered that the sun and all other celestial bodies revolve around Earth. However, they did not consider them as worlds. In Greek understanding, the world was composed by both Earth and the celestial objects with noticeable movements.
2222:. Bruno wrote that other worlds "have no less virtue nor a nature different to that of our earth" and, like Earth, "contain animals and inhabitants". Bruno's belief in the plurality of worlds was one of the charges leveled against him by the
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had in 1977 discussed for a year strategies for interacting with extraterrestrial life or intelligence. The discussion ended without any conclusions. As of 2010, the UN lacks response mechanisms for the case of an extraterrestrial contact.
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further argued that even if the search for extraterrestrial life proves to be unsuccessful, the endeavor itself could have beneficial consequences by assisting humanity in its attempt to actualize superior ways of living here on Earth.
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One of the NASA divisions is the Office of Safety and
Mission Assurance (OSMA), also known as the Planetary Protection Office. A part of its mission is to "rigorously preclude backward contamination of Earth by extraterrestrial life."
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strove to elevate the level of public discourse on the topic of extraterrestrial life by tracing the evolution of philosophical thought over the centuries from ancient times into the modern era. His review of the contributions made by
4995:
McKay, David S.; Gibson, Everett K. Jr.; Thomas-Keprta, Kathie L.; Vali, Hojatollah; Romanek, Christopher S.; et al. (August 1996). "Search for Past Life on Mars: Possible Relic
Biogenic Activity in Martian Meteorite ALH84001".
4521:
Amils, Ricardo; GonzĂĄlez-Toril, Elena; FernĂĄndez-Remolar, David; GĂłmez, Felipe; Aguilera, Ăngeles; RodrĂguez, Nuria; Malki, MustafĂĄ; GarcĂa-Moyano, Antonio; FairĂ©n, Alberto G.; de la Fuente, Vicenta; Luis Sanz, JosĂ© (February 2007).
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Although the idea of extraterrestrial peoples became feasible once astronomy developed enough to understand the nature of planets, they were not thought of as being any different from humans. Having no scientific explanation for the
1746:, which can be detectable. The natural abundance of carbon, which is also relatively reactive, makes it likely to be a basic component of the development of a potential extraterrestrial technological civilization, as it is on Earth.
1933:, since that gas is highly reactive and generally would not last long without constant replenishment. This replenishment occurs on Earth through photosynthetic organisms. One way to analyse the atmosphere of an exoplanet is through
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extreme environments that seem unlikely to have harbored life at least at one point in Earth's history. Fossil evidence as well as many historical theories backed up by years of research and studies have marked environments like
956:
must be broken by a source of energy. The traditional sources of energy in the cosmos are the stars, such as for life on Earth, which depends on the energy of the sun. However, there are other alternative energy sources, such as
1625:, or RNA, which is similar in function to DNA. This finding suggests that complex organic molecules may form in stellar systems prior to the formation of planets, eventually arriving on young planets early in their formation.
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took place thousands of millions of years after the origin of life, and its causes are not fully known yet. On the other hand, the jump to multicellularity took place several times, which suggests that it could be a case of
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On the other hand, other scientists are pessimistic. Jacques Monod wrote that "Man knows at last that he is alone in the indifferent immensity of the universe, whence which he has emerged by chance". In 2000, geologist and
878:
2004:
were the first to consider that the universe is inherently understandable and rejected explanations based on supernatural incomprehensible forces, such as the myth of the Sun being pulled across the sky in the chariot of
4403:
Bernstein, Harris; Byerly, Henry C.; Hopf, Frederick A.; et al. (June 1983). "The Darwinian Dynamic". The Quarterly Review of Biology. 58 (2): 185â207. doi:10.1086/413216. JSTOR 2828805. S2CID 83956410
5999:
R.; Hall, J. R.; Ibrahim, K.; Klaus, T. C.; McCauliff, S. D.; Middour, C. K.; Sabale, A.; Uddin, A. K.; Wohler, B.; Barclay, T.; Still, M. (2013). "Detection of Potential Transit Signals in the First 12 Quarters of
170:, from an exterior perspective, due to a layer of "fiery brightness" in the outer layer of the atmosphere. He theorised all extraterrestrial bodies could be inhabited by men, plants, and animals, including the Sun.
1085:, an atmosphere devoid of oxygen, and a solvent other than water. The low temperatures required would add an extra problem, the difficulty to kickstart a process of abiogenesis to create life in the first place.
4874:"Life on Venus? The Picture Gets Cloudier â Despite doubts from many scientists, a team of researchers who said they had detected an unusual gas in the planet's atmosphere were still confident of their findings"
1515:. Although all the unusual properties of the meteorite were eventually explained as the result of inorganic processes, the controversy over its discovery laid the groundwork for the development of astrobiology.
6926:"Seeing and Interpreting Martian Oceans and Canals | Life on Other Worlds | Articles and Essays | Finding Our Place in the Cosmos: From Galileo to Sagan and Beyond | Digital Collections | Library of Congress"
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seen on the Moon or Mars were immediately attributed to Selenites or Martians, and later ones (such as more powerful telescopes) revealed that all such discoveries were natural features. A famous case is the
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that will eventually form planets. An older star such as the Sun would have no natural reason to have excess infrared radiation. The presence of heavy elements in a star's light-spectrum is another potential
882:
The Drake equation has proved controversial since, although it is written as a math equation, none of its values were known at the time. Although some values may eventually be measured, others are based on
6925:
5685:"Poison Gas Hints at Potential for Life on an Ocean Moon of Saturn - A researcher who has studied the icy world said "the prospects for the development of life are getting better and better on Enceladus.""
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is the only celestial body in the Solar System besides Earth that has liquid bodies on the surface. It has rivers, lakes, and rain of hydrocarbons, methane, and ethane, and even a cycle similar to Earth's
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carried out in some way other than conventional radio transmission. At the same time, the data returned by space probes, and giant strides in detection methods, have allowed science to begin delineating
1530:, based their claim on methane signatures found in Mars's atmosphere resembling the methane production of some forms of primitive life on Earth, as well as on their own study of primitive life near the
2841:, said the search for extraterrestrial life is one of the main goals of deep space research. He also acknowledged the possibility of existence of primitive life on other planets of the Solar System.
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in the sky were not just lights, but physical objects. The notion that life may exist in them as well soon became an ongoing topic of discussion, although one with no practical ways to investigate.
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orbiter. The low-resolution photos showed a rock formation that resembled a human face, but later spacecraft took photos in higher detail that showed that there was nothing special about the site.
2128:, and the dispute intertwined with religious ones. Still, the Church did not react to those topics in a homogeneous way, and there were stricter and more permissive views within the church itself.
442:) would not appear until 50 million years later, created through stellar fusion. At that point, the difficulty for life to appear was not the temperature, but the scarcity of free heavy elements.
3314:
Mapelli, Francesca; Marasco, Ramona; Rolli, Eleonora; Daffonchio, Daniele; Donachie, Stuart; Borin, Sara (2015), Rouwet, Dmitri; Christenson, Bruce; Tassi, Franco; Vandemeulebrouck, Jean (eds.),
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atom makes it the element most likely to provide solutions, even exotic solutions, to the problems of survival of life on other planets. However, he also considered that the conditions found on
6775:"Peoples & Creatures of the Moon | Life on Other Worlds | Articles and Essays | Finding Our Place in the Cosmos: From Galileo to Sagan and Beyond | Digital Collections | Library of Congress"
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exists or has ever existed within the Solar System. Astrobiologist Mary Voytek points out that it would be unlikely to find large ecosystems, as they would have already been detected by now.
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1553:
of starlight reflected from lifeless planets. If Earth was studied from afar with this system, it would reveal a shade of green, as a result of the abundance of plants with photosynthesis.
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are universal, which means that the forces that would facilitate or prevent the existence of life would be the same ones as on Earth. According to this argument, made by scientists such as
193:
Since the mid-20th century, active research has taken place to look for signs of extraterrestrial life, encompassing searches for current and historic extraterrestrial life, and a narrower
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rather than water has been suggested as an alternative, though this solvent appears less suitable than water. It is also conceivable that there are forms of life whose solvent is a liquid
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of each specific star influences the local habitability. The type of star also defines the time the habitable zone will exist, as its presence and limits will change along with the star's
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Santerne, A.; DĂaz, R. F.; Almenara, J.-M.; Lethuillier, A.; Deleuil, M.; Moutou, C. (2013). "Astrophysical false positives in exoplanet transit surveys: Why do we need bright stars?".
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for the heliocentric model, which was considered heretical, and forced to recant it. The best-known early-modern proponent of ideas of extraterrestrial life was the Italian philosopher
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The apparent contradiction between high estimates of the probability of the existence of extraterrestrial civilisations and the lack of evidence for such civilisations is known as the
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warned in 2010 that humans should not try to contact alien life forms. He warned that aliens might pillage Earth for resources. "If aliens visit us, the outcome would be much as when
2776:, the couple reported that they were abducted and experimented on by aliens with oversized heads, big eyes, pale grey skin, and small noses, a description that eventually became the
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Sahlmann, J.; Lazorenko, P. F.; SĂ©gransan, D.; MartĂn, Eduardo L.; Queloz, D.; Mayor, M.; Udry, S. (August 2013). "Astrometric orbit of a low-mass companion to an ultracool dwarf".
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It is unclear if life and intelligent life are ubiquitous in the cosmos or rare. The hypothesis of ubiquitous extraterrestrial life relies on three main ideas. The first one, the
5661:
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are examples of life forming under difficult circumstances, provide parallels to the extreme environments on other planets and support the possibility of extraterrestrial life.
5185:
Beegle, Luther W.; Wilson, Michael G.; Abilleira, Fernando; Jordan, James F.; Wilson, Gregory R. (August 2007). "A Concept for NASA's Mars 2016 Astrobiology Field Laboratory".
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3001:"A new frontier is opening in the search for extraterrestrial life â The reason we haven't found life elsewhere in the universe is simple: We haven't really looked until now"
1164:
considers that convergent evolution would lead to kingdoms similar to our plants and animals, and that many features are likely to develop in alien animals as well, such as
894:, there are nearly 2 trillion galaxies in the observable universe. It is estimated that at least ten per cent of all Sun-like stars have a system of planets, i.e. there are
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a planet contains, and that the complexity of life itself is reflected in the information density of planetary environments, which in turn can be computed from its niches.
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was a good idea; one result was a statement, signed by many, that a "worldwide scientific, political and humanitarian discussion must occur before any message is sent".
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In February 2005 NASA scientists reported they may have found some evidence of extraterrestrial life on Mars. The two scientists, Carol Stoker and Larry Lemke of NASA's
1028:. A replacement for carbon would need to be able to create complex molecules, store information required for evolution, and be freely available in the medium. To create
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estimates 700 objects >10 solar masses (roughly the mass of Mars) per main-sequence star between 0.08 and 1 Solar mass, of which there are billions in the Milky Way.
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life is common. Ward and Brownlee are open to the idea of evolution on other planets that is not based on essential Earth-like characteristics such as DNA and carbon.
2342:
is the more accepted theory, a number of authors reclaimed the term "panspermia" and proposed that life was brought to Earth from elsewhere. Some of those authors are
1234:
The aspects of these harsh environments that make them ideal for the origin of life on Earth, as well as the possibility of creation of life on other planets, is the
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2826:. According to the document, one of the research objectives of the program is the search for extraterrestrial life. It is also one of the objectives of the Chinese
1112:
itself, the capacity to avoid damage/decay, and the capacity to acquire and process resources in support of the first two capacities. Life on Earth started with an
3931:
2104:
authors talk about other worlds, they talk about places located at the center of their own systems, and with their own stellar vaults and cosmos surrounding them.
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within the habitable zones of their stars. Since 1992, over four thousand exoplanets have been discovered (7,026 planets in 4,949 planetary systems including 1007
609:
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flew inside one of these, but could not make a full study because NASA did not expect this phenomenon and did not equip the probe to study ocean water. Still,
2968:
For the purpose of this 1 in 5 statistic, "habitable zone" means the region with 0.25 to 4 times Earth's stellar flux (corresponding to 0.5â2 AU for the Sun).
1089:, head of the Jet Propulsion Laboratory bioscience section for the Mariner and Viking missions from 1965 to 1976 considered that the great versatility of the
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hypothesis claim that aliens would have visited Earth in antiquity and prehistoric times but people would have failed to understand it by then. Most UFOs or
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to happen there. The second is that the chemical elements that make up life, such as carbon and water, are ubiquitous in the universe. The third is that the
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Bond, Jade C.; O'Brien, David P.; Lauretta, Dante S. (June 2010). "The Compositional Diversity of Extrasolar Terrestrial Planets. I. In Situ Simulations".
3584:. Astrobiology Science Conference 2010: Evolution and Life: Surviving Catastrophes and Extremes on Earth and Beyond. 20â26 April 2010. League City, Texas.
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did: orbits were not perfect circles, but ellipses. This knowledge benefited the Copernican model, which worked now almost perfectly. The invention of the
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there was little thought about the conditions of each celestial body: it was simply assumed that life would thrive anywhere. This theory was disproved by
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suggest that a random universe capable of supporting life is likely to be just barely able to do so, giving a potential explanation to the Fermi paradox.
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7557:
4461:
Stevenson, David S.; Large, Sean (25 October 2017). "Evolutionary exobiology: Towards the qualitative assessment of biological potential on exoplanets".
3453:
Baum, Seth; Haqq-Misra, Jacob; Domagal-Goldman, Shawn (June 2011). "Would Contact with Extraterrestrials Benefit or Harm Humanity? A Scenario Analysis".
3409:
3032:
2701:
1545:
rover on Mars. It is designed to assess the past and present habitability on Mars using a variety of scientific instruments. The rover landed on Mars at
197:. Depending on the category of search, methods range from analysis of telescope and specimen data to radios used to detect and transmit communications.
10709:
3804:
422:, it cooled to temperate levels, but the elements that make up living things did not exist yet. The only freely available elements at that point were
11903:
9433:
9423:
8516:
8506:
6300:
3067:
821:
356:
346:
1503:. Some claim to have identified evidence that microbial life has existed on Mars. In 1996, a controversial report stated that structures resembling
11587:
10347:
10049:
8803:
8112:
5514:
Kwok, Sun; Zhang, Yong (26 October 2011). "Mixed aromaticâaliphatic organic nanoparticles as carriers of unidentified infrared emission features".
4652:
Georgieva, Magdalena N.; Little, Crispin T.S.; Maslennikov, Valeriy V.; Glover, Adrian G.; Ayupova, Nuriya R.; Herrington, Richard J. (June 2021).
1189:
5427:
11542:
10704:
10033:
8215:
6201:
2827:
1652:, some of which are yet to be better identified and understood. According to the researchers, "these compounds could potentially support extant
174:
wrote that there was no means to prove the stars were not inhabited by "intelligent creatures", but their existence was a matter of speculation.
572:
maintains that life on Earth is possible because of a series of factors that range from the location in the galaxy and the configuration of the
10374:
8808:
4394:
Horowitz, N.H. (1986). Utopia and Back and the search for life in the solar system. New York: W.H. Freeman and Company. ISBN 0-7167-1766-2
2513:
through the mass media. The public interest in extraterrestrial life and the lack of discoveries by mainstream science led to the emergence of
921:
382:
6177:
4142:
10920:
10317:
5651:
2811:
816:
Drake's proposed estimates are as follows, but numbers on the right side of the equation are agreed as speculative and open to substitution:
6719:"Giordano Bruno: On the Infinite Universe and Worlds (De l'Infinito Universo et Mondi) Introductory Epistle: Argument of the Third Dialogue"
10468:
9338:
7720:
4097:
3210:"Liquid and supercritical CO2 as an organic solvent in Hadean seafloor hydrothermal systems: implications for prebiotic chemical evolution"
5835:
Whitmire, Daniel P.; Wright, David P. (April 1980). "Nuclear waste spectrum as evidence of technological extraterrestrial civilizations".
909:
spacecraft estimated that the Milky Way contains at least as many planets as it does stars, resulting in 100â400 billion exoplanets.
10379:
9508:
9111:
7643:
1954:
1698:
Although most searches are focused on the biology of extraterrestrial life, an extraterrestrial intelligence capable enough to develop a
2361:
The science fiction genre, although not so named during the time, developed during the late 19th century. The expansion of the genre of
10026:
9763:
8426:
6718:
2057:
other planets to exist elsewhere. Under that reasoning, Earth was not only in the center, it was also the only planet in the universe.
1347:
Although the giant planets themselves are highly unlikely to have life, there is much hope to find it on moons orbiting these planets.
1265:
1100:
Even if extraterrestrial life is based on carbon and uses water as a solvent, like Earth life, it may still have a radically different
1072:(four bonds). As for abundance, carbon, nitrogen, and silicon are the most abundant ones in the universe, far more than the others. On
496:, due to crushing atmospheric pressures. The actual distances for the habitable zones vary according to the type of star, and even the
252:
5957:
4165:
Wang, Zhi-Wei; Braunstein, Samuel L. (2023). "Sciama's argument on life in a random universe and distinguishing apples from oranges".
11247:
10563:
9950:
6529:
5590:
JĂžrgensen, Jes K.; Favre, CĂ©cile; Bisschop, Suzanne E.; Bourke, Tyler L.; van Dishoeck, Ewine F.; Schmalzl, Markus (September 2012).
1534:
in Spain. NASA officials soon distanced NASA from the scientists' claims, and Stoker herself backed off from her initial assertions.
5228:
4970:
1706:, effects on the native planet that may not be caused by natural causes. There are three main types of technosignatures considered:
1443:
The scientific search for extraterrestrial life is being carried out both directly and indirectly. As of September 2017, 3,667
11592:
9443:
9358:
8853:
8521:
1918:
instead. Almost all of the planets detected so far are within the Milky Way, but there have also been a few possible detections of
1795:
1673:
589:
305:
194:
5795:
2318:. By 1909 better telescopes and the best perihelic opposition of Mars since 1877 conclusively put an end to the canal hypothesis.
200:
The concept of extraterrestrial life, and particularly extraterrestrial intelligence, has had a major cultural impact, especially
11913:
9861:
8888:
8658:
7026:
We must regard it as probably to the highest degree that there are countless seed-bearing meteoritic stones moving through space.
1895:
1883:
1208:
It is common knowledge that the conditions on other planets in the solar system, in addition to the many galaxies outside of the
5367:
Callahan, M.P.; Smith, K.E.; Cleaves, H.J.; Ruzica, J.; Stern, J.C.; Glavin, D.P.; House, C.H.; Dworkin, J.P. (11 August 2011).
1780:; such elements would (in theory) be found if the star were being used as an incinerator/repository for nuclear waste products.
166:
wrote in 1440 that Earth is "a brilliant star" like other celestial objects visible in space; which would appear similar to the
10779:
10538:
10458:
9194:
7505:"Regarding Messaging To Extraterrestrial Intelligence (METI) / Active Searches For Extraterrestrial Intelligence (Active SETI)"
7291:
5984:
5568:
3000:
1212:, are very harsh and seem to be too extreme to harbor any life. The environmental conditions on these planets can have intense
1180:. Scientists from the University of Oxford analysed it from the perspective of evolutionary theory and wrote in a study in the
74:
2329:
in the 19th century. Popular belief in thriving alien civilisations elsewhere in the solar system still remained strong until
1580:
that serve as building blocks of life may be generated within asteroids and comets. In October 2011, scientists reported that
507:
Life on Earth is quite ubiquitous across the planet and has adapted over time to almost all the available environments in it,
11908:
9851:
8559:
8166:
8143:
8122:
8056:
8034:
7994:
7963:
7933:
7910:
7891:
7863:
7844:
7825:
7797:
7778:
7757:
7408:
7357:
6909:
6604:
6564:
6512:
5117:
4370:
3941:
3778:
3751:
3718:
3614:
3345:
3183:
2742:
and its relation to other species, there was no reason to expect them to be any other way. This was changed by the 1859 book
1181:
11160:
2768:
Real-life events sometimes captivate people's imagination and this influences the works of fiction. For example, during the
9636:
9428:
9413:
8511:
8496:
8256:
6876:
Is Mars Habitable? A Critical Examination of Professor Lowell's Book "Mars and Its Canals," With an Alternative Explanation
6800:
351:
336:
119:
speculates about the existence of sapient life elsewhere in the universe. The science of extraterrestrial life is known as
9523:
7425:
6658:
6115:
Cassan, A.; et al. (11 January 2012). "One or more bound planets per Milky Way star from microlensing observations".
5765:
2859:
stated that the probability of detecting life in outer space is "quite large". But he disagrees with his former colleague
2120:. However, as the Greek atomist doctrine held that the world was created by random movements of atoms, with no need for a
11918:
11608:
11535:
9403:
8486:
8461:
8208:
4935:
3524:
326:
7534:
7462:
7318:
6059:(Press release). Planetary Habitability Laboratory, University of Puerto Rico at Arecibo. 3 January 2012. Archived from
11412:
9965:
9408:
9333:
9121:
8964:
8491:
7508:
2893:
2654:
1992:
The modern concept of extraterrestrial life is based on assumptions that were not commonplace during the early days of
1328:
used to be quite abundant, forming rivers, lakes, and perhaps even oceans. Mars may have been habitable back then, and
1025:
937:
375:
331:
209:
contact intelligent extraterrestrial life. Others â citing the tendency of technologically advanced human societies to
7142:
2147:
11312:
9945:
9866:
9418:
8501:
6983:
6668:
6267:
5684:
3983:
3644:
2598:
on other worlds, and to confirm that at least other planets are plentiful, though aliens remain a question mark. The
2347:
887:
and are not knowable by their very nature. This does not allow one to make noteworthy conclusions from the equation.
806:= the fraction of civilisations that develop a technology to broadcast detectable signs of their existence into space
341:
1251:. With the little amount of information that scientists have found regarding the atmosphere on other planets in the
9970:
9803:
9323:
9058:
8653:
5916:
2903:
1929:
One sign that a planet probably already contains life is the presence of an atmosphere with significant amounts of
245:
6060:
4754:"Composition and origin of the atmosphere of Jupiterâan update, and implications for the extrasolar giant planets"
568:
Other authors consider instead that life in the cosmos, or at least multicellular life, may be actually rare. The
11933:
11437:
9908:
9783:
9438:
7770:
The Inner Limits of Outer Space: A Psychologist Critiques Our Efforts to Communicate With Extraterrestrial Beings
5591:
4850:
4496:
2898:
2065:. There are multiple "worlds" mentioned in Jain scriptures that support human life. These include, among others,
6366:
2288:
Speculation about life on Mars increased in the late 19th century, following telescopic observation of apparent
1151:
The evolution from simple cells to eukaryotes, and from them to multicellular lifeforms, is not guaranteed. The
11928:
11923:
11898:
11801:
11528:
9793:
9738:
8643:
8201:
3043:
2769:
2107:
The Greek ideas and the disputes between atomists and Aristotelians outlived the fall of the Greek empire. The
1903:
1825:
1184:
that aliens may be similar to humans. The planetary context would also have an influence: a planet with higher
949:
99:. No extraterrestrial life has yet been conclusively detected. Such life might range from simple forms such as
7682:
7565:
5076:
969:. There are ecosystems on Earth in deep areas of the ocean that do not receive sunlight, and take energy from
11719:
11618:
11362:
10006:
9841:
9701:
9513:
9393:
8908:
8776:
8585:
8476:
5461:
1735:
travel across space means that a potential answer may arrive decades or centuries after the initial message.
1292:
524:
368:
104:
68:
38:
2673:, to expand efforts to search for extraterrestrial life. The group contracted the services of the 100-meter
2244:
The possibility of extraterrestrials remained a widespread speculation as scientific discovery accelerated.
11397:
9383:
9096:
8969:
8466:
3958:
2883:
2863:
who stated that there are contacts between an advanced alien civilisation and some of Earth's governments.
2721:
2362:
2155:
479:
201:
31:
5889:
1926:
also considers a wide range of other factors in determining the suitability of a planet for hosting life.
10593:
9975:
9960:
9876:
9553:
8954:
8678:
7811:
4800:
Marcq, Emmanuel; Mills, Franklin P.; Parkinson, Christopher D.; Vandaele, Ann Carine (30 November 2017).
3927:
2610:
2108:
2046:
who thought that those elements were exclusive of Earth and that the cosmos was made of a fifth one, the
9478:
7208:
Ailleris, Philippe (JanuaryâFebruary 2011). "The lure of local SETI: Fifty years of field experiments".
5288:
2497:, and others. Astrobiology studies life from Earth as well, but with a cosmic perspective. For example,
11827:
11551:
9808:
9187:
9028:
8746:
8668:
4873:
2762:
2522:
2218:, who argued in the 16th century for an infinite universe in which every star is surrounded by its own
2048:
1707:
419:
17:
9483:
5435:
4801:
3550:
2292:â which soon, however, turned out to be optical illusions. Despite this, in 1895, American astronomer
37:
This article is about any kind of extraterrestrial life. For aliens with human-like intelligence, see
11352:
11347:
10528:
9886:
9717:
9308:
8613:
8421:
7884:
The Biological Universe: The Twentieth Century Extraterrestrial Life Debate and the Limits of Science
7625:
4443:
2948:
2944:
2223:
1382:
detected complex organic molecules, salts, evidence of hydrothermal activity, hydrogen, and methane.
953:
182:
on Earth that do support forms of life and are often hypothesized to be the origin of life on Earth.
8087:
3155:
2256:
is populated by alien life. Other scholars of the period who championed "cosmic pluralism" included
2014:
extraterrestrial life, such as Earth being round and not flat. The cosmos was first structured in a
1108:. It has been proposed that to undergo natural selection a living entity must have the capacity to
213:
or destroy less advanced societies â argue it may be dangerous to actively draw attention to Earth.
11570:
11392:
9918:
8786:
5939:
5342:
2744:
2670:
2311:
1412:
The science that searches and studies life in the universe, both on Earth and elsewhere, is called
7038:
Demets, René (October 2012). "Darwin's Contribution to the Development of the Panspermia Theory".
1310:
that was likely similar to Earth in its early stages and developed in a different way. There is a
126:
Speculation about the possibility of inhabited worlds beyond Earth dates back to antiquity. Early
11472:
9813:
9579:
9398:
8481:
5486:
4753:
4653:
4523:
2947:. Data for Sun-like stars wasn't available so this statistic is an extrapolation from data about
2506:
2415:
1731:
1538:
1483:
1324:
is a cold and almost airless desert, inhospitable to life. However, recent studies revealed that
1248:
310:
178:
8025:
Contact with Alien Civilizations â Our Hopes and Fears about Encountering Extraterrestrials
6959:
6084:
Sf2A-2013: Proceedings of the Annual Meeting of the French Society of Astronomy and Astrophysics
4105:
2343:
2027:, a substance that created the world, and that the world would eventually return to the cosmos.
11327:
10292:
10202:
10079:
10074:
9373:
9262:
9038:
9013:
9003:
8843:
8722:
8526:
8451:
7807:
7246:- "Extraterrestrial Intelligent Life",. Beck, Lewis White. Vol 45 (1971-1972) pp. 5-21 on JSTOR
7173:
Cross, Anne (2004). "The Flexibility of Scientific Rhetoric: A Case Study of UFO Researchers".
5048:
3923:
2595:
2432:
2424:
Some major international efforts to search for extraterrestrial life, clockwise from top left:
2322:
1923:
1899:
1833:
1629:
1433:
891:
484:
400:
7647:
7644:"China Focus: Earth's largest radio telescope to search for "new worlds" outside solar system"
5255:
3768:
3743:
3604:
130:
writers discussed the idea of a "plurality of worlds" as proposed by earlier thinkers such as
11893:
11689:
11658:
11382:
10995:
10613:
10160:
9994:
9933:
9758:
9453:
9180:
9141:
9043:
8868:
8761:
8596:
8531:
6829:
6594:
3576:
3141:
The extraterrestrial life debate, antiquity to 1915: a source book/edited by Michael J. Crowe
3111:
The extraterrestrial life debate, antiquity to 1915: a source book/edited by Michael J. Crowe
3096:
The extraterrestrial life debate, antiquity to 1915: a source book/edited by Michael J. Crowe
2908:
2823:
2627:
2530:
2445:
2351:
2187:
2174:
2036:
that thought that matter at both Earth and the cosmos was equally made of small atoms of the
1604:
1256:
occur on these planets' surfaces and possibly result in the origin of extraterrestrial life.
1024:
that would compose it. Life on Earth is largely composed of carbon, but there could be other
703:{\displaystyle N=R_{\ast }\cdot f_{p}\cdot n_{e}\cdot f_{\ell }\cdot f_{i}\cdot f_{c}\cdot L}
569:
225:
6722:
6439:
6365:
5077:"Mars Meteorite with Odd 'Tunnels' & 'Spheres' Revives Debate Over Ancient Martian Life"
4769:
4539:
4141:
3708:
3667:
3384:
3042:
1463:. As of 8 February 2021, an updated status of studies considering the possible detection of
281:
11938:
11613:
11580:
11443:
11427:
11052:
10423:
10394:
10275:
10099:
9940:
9928:
9823:
9773:
9768:
9667:
9610:
9599:
9503:
9353:
9237:
9227:
9131:
9018:
9008:
8979:
8796:
8691:
8009:
7345:
7217:
7047:
6999:
6845:
6435:
6319:
6220:
6134:
6097:
6022:
5961:
5844:
5741:
5616:
5525:
5380:
5194:
5143:
5005:
4765:
4716:
4665:
4535:
4447:
4303:
4256:
4184:
4063:
4005:
3889:
3585:
3472:
3262:
3163:
2803:
2789:
2677:
2646:
2265:
2182:
improved the available data with naked-eye observatories, which worked with highly complex
2165:
there were many known inaccuracies in the geocentric model, but it was kept in use because
2131:
The first known mention of the term 'panspermia' was in the writings of the 5th-century BC
2082:
2042:
1993:
1960:
1919:
1683:
1678:
1527:
1318:, there are suspicions that microbial lifeforms may still survive in high-altitude clouds.
1157:
1141:
1082:
925:
721:
596:
used to estimate the number of active, communicative extraterrestrial civilisations in the
562:
558:
530:
6537:
5314:
4626:
4609:
1247:
and therefore, these carbon fixing compounds were necessary for the survival and possible
981:
have also been proposed as sources of energy, although they would be less efficient ones.
812:= the length of time over which such civilisations broadcast detectable signals into space
276:
8:
11709:
11575:
11387:
11367:
11180:
10870:
10358:
10222:
10197:
10165:
10084:
9923:
9748:
8944:
8791:
8771:
8717:
8683:
8578:
8250:
8238:
7977:
7975:, "Alone in the Milky Way: Why we are probably the only intelligent life in the galaxy",
7725:
7587:
7186:
7082:
5652:"What Is Life? - The answer matters in space exploration. But we still don't really know"
5232:
3006:
2923:
2853:
2753:
2661:
had earlier expressed similar concerns. On 20 July 2015, Hawking and Russian billionaire
2538:
2510:
2170:
1938:
1772:
1691:
1617:
1437:
1374:
1161:
904:
534:
451:
9533:
8013:
7477:
7349:
7221:
7051:
7003:
6849:
6323:
6224:
6138:
6101:
6026:
5848:
5745:
5620:
5529:
5384:
5198:
5147:
5049:"NASA Scientists Find Evidence of Water in Meteorite, Reviving Debate Over Life on Mars"
5009:
4720:
4669:
4307:
4260:
4188:
4067:
4009:
3893:
3805:"Expectation of extraterrestrial life built more on optimism than evidence, study finds"
3589:
3476:
3435:
3315:
3266:
3167:
1368:
with another subsurface ocean, may not need to be dug, as it releases water to space in
993:
and other elements, along with water, might enable the formation of living organisms on
920:
claimed that life's existence in the universe depends on various fundamental constants.
11877:
11485:
11407:
11377:
11322:
11199:
11175:
10674:
10608:
10473:
10433:
10284:
10247:
10207:
10186:
10129:
10104:
9753:
9066:
8923:
8873:
8663:
8591:
8155:
8075:
8023:
7922:
7815:
7504:
7457:
7242:
7190:
7020:
6987:
6962:(1834). "Analysis of the Alais meteorite and implications about life in other worlds".
6874:
6451:
6425:
6337:
6309:
6243:
6210:
6196:
6158:
6124:
6087:
6038:
6012:
5757:
5731:
5689:
5632:
5606:
5549:
5403:
5368:
5167:
5029:
4878:
4832:
4706:
4478:
4272:
4268:
4246:
4174:
4136:
4079:
4053:
4021:
3995:
3905:
3496:
3462:
3379:
3291:
3250:
3175:
3037:
2795:
2526:
2451:
2315:
2037:
1860:
1821:
1809:
1751:
1344:
and outwards, are locked in permanent deep-freeze, but cannot be ruled out completely.
1307:
1165:
1152:
994:
720:= the number of Milky Way galaxy civilisations already capable of communicating across
593:
404:
135:
5592:"Detection of the simplest sugar, glycolaldehyde, in a solar-type protostar with ALMA"
4901:
4777:
4075:
997:
with a chemical make-up and temperature range similar to that of Earth. Life based on
11809:
11694:
11432:
11015:
10915:
10885:
10803:
10543:
10428:
10384:
10332:
10139:
10134:
10066:
9881:
9631:
9584:
9548:
9288:
9267:
8699:
8569:
8268:
8262:
8162:
8139:
8133:
8118:
8052:
8030:
7990:
7959:
7953:
7929:
7906:
7887:
7859:
7840:
7821:
7793:
7774:
7768:
7753:
7404:
7353:
7194:
7088:
7063:
6905:
6899:
6880:
6664:
6600:
6560:
6508:
6455:
6341:
6332:
6295:
6272:
6248:
6150:
6042:
5856:
5761:
5717:
5628:
5541:
5408:
5210:
5159:
5113:
5107:
5021:
4836:
4824:
4734:
4631:
4590:
4582:
4482:
4366:
4331:
4326:
4291:
4276:
3937:
3909:
3774:
3747:
3736:
3714:
3610:
3488:
3341:
3296:
3278:
3231:
3179:
2878:
2739:
2622:
2459:
2428:
2385:
2261:
2230:
2099:
2086:
2010:
1657:
1577:
1512:
1311:
1239:
1235:
1227:
1218:
1105:
966:
561:, which states that Earth does not occupy a unique position in the Universe, and the
501:
183:
10018:
8546:
7229:
6801:"The Devine Pedagogy: Theological Explorations of Intelligent Extraterrestrial Life"
6034:
5636:
5171:
5033:
4678:
4083:
4025:
3500:
3484:
2708:
and whether transmitting a message to possible intelligent extraterrestrials in the
171:
154:
writers typically assumed extraterrestrial "worlds" are inhabited by living beings.
11853:
11782:
11752:
11684:
11653:
11643:
11509:
11497:
11417:
11317:
11222:
11170:
10603:
10478:
10443:
10364:
10352:
10312:
10217:
10150:
9493:
9146:
9086:
9033:
8939:
8913:
8813:
8390:
8244:
7662:"Đ ĐŸĐłĐŸĐ·ĐžĐœ ĐŽĐŸĐżŃŃŃОл ŃŃŃĐ”ŃŃĐČĐŸĐČĐ°ĐœĐžĐ” Đ¶ĐžĐ·ĐœĐž ĐœĐ° ĐĐ°ŃŃĐ” Đž ĐŽŃŃгОŃ
ĐżĐ»Đ°ĐœĐ”ŃĐ°Ń
ĐĄĐŸĐ»ĐœĐ”ŃĐœĐŸĐč ŃĐžŃŃĐ”ĐŒŃ"
7606:
7225:
7182:
7055:
7015:
7007:
6853:
6443:
6327:
6238:
6228:
6162:
6142:
6030:
5852:
5749:
5722:
5624:
5553:
5533:
5516:
5398:
5388:
5202:
5151:
5013:
4966:
4816:
4773:
4724:
4673:
4621:
4574:
4543:
4470:
4358:
4321:
4311:
4264:
4192:
4071:
4013:
3897:
3849:
3480:
3331:
3323:
3286:
3270:
3221:
3171:
2856:
2681:
2549:
2505:
The 20th century came with great technological advances, speculations about future
2355:
2245:
2219:
2162:
2113:
2094:
2015:
1975:
1739:
1649:
1641:
1622:
1585:
1448:
1252:
1209:
1197:
1073:
1021:
917:
538:
468:
447:
443:
163:
155:
6447:
2509:, and an increased basic knowledge of science by the general population thanks to
1487:
Lifeforms produce a variety of biosignatures that may be detectable by telescopes.
11767:
11714:
11628:
11623:
11105:
11080:
10618:
10558:
10342:
10242:
10227:
10212:
10119:
10109:
9788:
9621:
9247:
9161:
9151:
8974:
8833:
8818:
8781:
8766:
8712:
8638:
8331:
8099:
7373:
6964:
6502:
5017:
3854:
3546:
3327:
2873:
2773:
2757:
2756:. Now with the notion that evolution on other planets may take other directions,
2642:
2617:
2293:
2199:
2191:
1887:
1767:
1759:
1755:
1754:
in the atmosphere can also be a clear technosignature, considering their role in
1703:
1687:
1531:
1369:
1356:
1352:
1340:
are unlikely to contain life. The most distant solar system bodies, found in the
1109:
1086:
962:
550:
205:
144:
112:
7107:
5155:
2517:
that provided affirmative, if questionable, answers to the existence of aliens.
1621:, which is located 400 light years from Earth. Glycolaldehyde is needed to form
11841:
11757:
11735:
11648:
11342:
11307:
11090:
10980:
10945:
10930:
10865:
10860:
10759:
10659:
10578:
10553:
10518:
10463:
10438:
10307:
10155:
9707:
9303:
9242:
9217:
9048:
8949:
8878:
8828:
8704:
8602:
8339:
8157:
Alien Worlds â Social and Religious Dimensions of Extraterrestrial Contact
8044:
5753:
4752:
Atreya, S.K; Mahaffy, P.R; Niemann, H.B; Wong, M.H; Owen, T.C (February 2003).
4695:"Creation and Evolution of Impact-generated Reduced Atmospheres of Early Earth"
4296:
Proceedings of the National Academy of Sciences of the United States of America
4196:
4127:
3370:
3226:
3209:
2913:
2834:
2799:
2749:
2685:
2674:
2666:
2607:
2602:, detected in 1977 by a SETI project, remains a subject of speculative debate.
2578:
2574:
2367:
2304:
in 1906, proposing that the canals were the work of a long-gone civilisation.
2289:
2215:
2211:
2203:
2132:
2001:
1837:
1718:
1661:
1608:
1519:
1243:
1169:
974:
884:
873:{\displaystyle 10{,}000=5\cdot 0.5\cdot 2\cdot 1\cdot 0.2\cdot 1\cdot 10{,}000}
738:
585:
520:
497:
492:
are not considered habitable even if they orbit close enough to their stars as
187:
142:'s idea of innumerable worlds "throughout the boundless immensity of space" in
116:
11520:
5369:"Carbonaceous meteorites contain a wide range of extraterrestrial nucleobases"
4928:"UCR Team Among Scientists Developing Guidebook for Finding Life Beyond Earth"
4820:
4693:
Zahnle, Kevin J.; Lupu, Roxana; Catling, David C.; Wogan, Nick (1 June 2020).
4547:
4474:
3901:
1836:
has also detected a few thousand candidate planets, of which about 11% may be
533:
allows for plenty of planets to have a similar habitability to Earth, and the
11887:
11772:
11372:
11227:
11110:
11085:
11066:
11010:
10890:
10848:
10843:
10583:
10573:
10533:
10408:
10302:
10257:
10232:
10114:
10094:
9363:
8994:
8959:
8918:
8441:
8431:
8304:
8274:
7875:
Plurality of Worlds: The Extraterrestrial Life Debate from Democratus to Kant
7721:"Israeli space chief says aliens may well exist, but they haven't met humans"
7701:
6858:
5818:"The Search for Extraterrestrial Intelligence (SETI) in the Optical Spectrum"
4828:
4738:
4635:
4586:
4350:
3668:"Goldilocks zone: Everything you need to know about the habitable sweet spot"
3492:
3410:"Want to Talk to Aliens? Try Changing the Technological Channel beyond Radio"
3282:
3235:
3072:
2658:
2570:
2534:
2514:
2326:
2310:
analysis of Mars's atmosphere began in earnest in 1894, when U.S. astronomer
2257:
2210:
The new ideas were met with resistance from the Catholic church. Galileo was
2121:
1934:
1872:
1743:
1653:
1546:
1504:
1460:
1394:
1351:, from the Jovian system, has a subsurface ocean below a thick layer of ice.
1348:
1325:
1315:
1279:
1177:
1129:
978:
943:
913:
396:
286:
261:
6233:
5487:"Astronomers Discover Complex Organic Matter Exists Throughout the Universe"
5393:
3826:
3606:
The privileged planet: how our place in the cosmos is designed for discovery
11865:
11813:
11747:
11448:
11302:
11155:
11095:
11075:
11047:
10975:
10855:
10838:
10793:
10744:
10649:
10369:
10322:
10170:
9388:
9343:
9328:
9313:
9298:
9257:
9252:
9232:
9222:
9203:
9156:
9101:
9081:
9076:
9071:
9023:
8898:
8838:
8471:
8436:
8135:
Life as we do not know it-the NASA search for (and synthesis of) alien life
7972:
7092:
7067:
6884:
6470:
6252:
6154:
5821:
5656:
5545:
5491:
5412:
5214:
5163:
4594:
4335:
3300:
2959:
For the purpose of this 1 in 5 statistic, Earth-sized means 1â2 Earth radii
2689:
2614:
2478:
2477:
The search and study of extraterrestrial life became a science of its own,
2455:
2307:
2253:
2234:
1853:
1844:
1805:
1777:
1711:
1699:
1569:
1496:
1492:
1456:
1413:
1407:
1385:
1329:
1213:
1193:
1101:
970:
792:
573:
557:
to exist somewhere else other than Earth. This argument is embodied in the
542:
508:
296:
271:
127:
120:
108:
7607:"Coronavirus Could Preview What Will Happen When Alien Life Reaches Earth"
7059:
5206:
5025:
4316:
3274:
2684:
in New South Wales, Australia. On 13 February 2015, scientists (including
2229:
The heliocentric model was further strengthened by the postulation of the
1750:
may likely be generated and used on such worlds as well. The abundance of
1721:
search the cosmos for potential forms of communication. They started with
11777:
11699:
11674:
11633:
11565:
11422:
11332:
11297:
11264:
11190:
11165:
11005:
10910:
10880:
10764:
10679:
10669:
10399:
10327:
9684:
9574:
9293:
9283:
9091:
8756:
8564:
8382:
8374:
8280:
7945:
Relations with alien intelligences â the scientific basis of metalaw
6556:
5870:
5273:
4729:
4694:
4520:
4000:
3028:
2705:
2693:
2662:
2599:
2533:
can be readily explained as sightings of Earth-based aircraft (including
2498:
2395:
2339:
2179:
2117:
2020:
1942:
1915:
1747:
1726:
1722:
1581:
1390:
1341:
1203:
1077:
1002:
989:
988:
in which biochemical reactions take place. It is highly unlikely that an
581:
493:
460:
455:
56:
8193:
6596:
Chaucer the Alchemist: Physics, Mutability, and the Medieval Imagination
6294:
Strigari, L. E.; BarnabĂš, M.; Marshall, P. J.; Blandford, R. D. (2012).
6146:
5718:"Detection of HCN and diverse redox chemistry in the plume of Enceladus"
5537:
4017:
2207:
the universe as on Earth, with nothing making the planet truly special.
1628:
In December 2023, astronomers reported the first time discovery, in the
1160:, and so likely to take place on other planets as well. Palaeontologist
463:. Alternatively, life may have formed less frequently, then spread â by
162:
could have visited extraterrestrial worlds to redeem their inhabitants.
11704:
11679:
11337:
11279:
11242:
11217:
11115:
10925:
10788:
9661:
9348:
9106:
8984:
8903:
8347:
8095:
7266:
6471:"Future Evidence for Extraterrestrial Life Might Come from Dying Stars"
3336:
2918:
2888:
2860:
2777:
2730:
2697:
2566:
2280:
2136:
1864:
1337:
1133:
1045:
1020:
Another unknown aspect of potential extraterrestrial life would be the
546:
472:
151:
131:
100:
5871:"Discovery of OGLE 2005-BLG-390Lb, the first cool rocky/icy exoplanet"
4562:
4524:"Extreme environments as Mars terrestrial analogs: The Rio Tinto case"
4029:
2810:
also provides guidelines for planetary protection. A committee of the
2726:
2272:
and Moon were considered candidates for extraterrestrial inhabitants.
2252:, was one of many 18thâ19th-century astronomers who believed that the
30:
This article is about the real-life topic. For aliens in fiction, see
11269:
11134:
10970:
10774:
10654:
10508:
10483:
9798:
9655:
9616:
9594:
9126:
8863:
8858:
8673:
8648:
8355:
7011:
5465:
5292:
5081:
4578:
3984:"Observed Properties of Exoplanets: Masses, Orbits and Metallicities"
3554:
2838:
2822:
In 2016, the Chinese Government released a white paper detailing its
2765:(CGI), and later on as CGI became more effective and less expensive.
2582:
2562:
2554:
2334:
2330:
2195:
2166:
2090:
1997:
1876:
1849:
1817:
1789:
1633:
1612:
1593:
1557:
1500:
1468:
1452:
1444:
1425:
1417:
1361:
1283:
1270:
1173:
1145:
1137:
1113:
1065:
742:
597:
489:
464:
62:
45:
6833:
6530:"Alien Ideas: Christianity and the Search for Extraterrestrial Life"
6178:"Astronomers answer key question: How common are habitable planets?"
5256:"Exclusive: NASA Researchers Claim Evidence of Present Life on Mars"
3322:, Berlin, Heidelberg: Springer Berlin Heidelberg, pp. 507â522,
3068:"Top 10: Controversial pieces of evidence for extraterrestrial life"
1980:
1710:, effects on the atmosphere, and planetary-sized structures such as
11836:
11638:
11237:
11149:
10950:
10813:
10798:
10769:
10638:
10413:
10237:
10181:
10175:
10144:
10089:
10057:
9856:
9846:
9778:
9569:
9543:
9518:
8848:
8823:
8735:
8728:
8623:
8554:
8188:
7903:
Life on Other Worlds: The 20th Century Extraterrestrial Life Debate
7482:
7244:
Proceedings and Addresses of the American Philosophical Association
5736:
5319:
4711:
4362:
4179:
2849:
their extraterrestrial origin can neither be confirmed nor denied.
2650:
2635:
2631:
2558:
2404:
2372:
2053:
1985:
1589:
1573:
1508:
1464:
1125:
1053:
1041:
577:
and not a reasonable scientific explanation for any gathered data.
423:
415:
139:
7401:
The Third Chimpanzee: The Evolution and Future of the Human Animal
6834:"Experiments as to the actuality of the "Canals" observed on Mars"
6430:
6314:
6215:
6129:
6092:
6017:
5611:
4251:
4058:
3467:
2978:
zone. Including red dwarfs would increase this to 40 billion.
1702:
may be detectable by other means as well. Technology may generate
565:, which states that there is nothing special about life on Earth.
11402:
11232:
11185:
11144:
11100:
11042:
11037:
11000:
10990:
10985:
10940:
10935:
10875:
10808:
10699:
10694:
10644:
10523:
10513:
10266:
9712:
9538:
8633:
8608:
8312:
8183:
7856:
The extraterrestrial life debate Antiquity to 1915: A Source Book
7661:
6394:
4927:
4563:"Origins of life and biochemistry under high-pressure conditions"
3551:"Life's Building Blocks May Have Formed in Dust Around Young Sun"
2518:
2183:
2125:
2116:. From there it eventually returned to Europe by the time of the
2062:
2032:
1988:
proposed that other worlds may have their own animals and plants.
1941:
its star, though this might only be feasible with dim stars like
1907:
1565:
1561:
1472:
1429:
1421:
1188:
would have smaller animals, and other types of stars can lead to
1185:
1061:
1049:
1014:
1006:
998:
985:
958:
769:= the average number of planets that can potentially support life
210:
8068:
Ufology as Anthropology: Race, Extraterrestrials, and the Occult
7588:"Press Conference by Director of Office for Outer Space Affairs"
6415:
6293:
5911:
4651:
4610:"Geomicrobiological processes in extreme environments: A review"
1800:
11453:
11274:
11256:
10719:
10689:
10191:
9955:
9528:
9498:
9488:
9448:
9172:
9116:
8628:
8536:
6081:
2807:
2709:
2249:
2006:
1996:. The first explanations for the celestial objects seen in the
1930:
1911:
1868:
1843:
There is at least one planet on average per star. About 1 in 5
1637:
1365:
1090:
1057:
1010:
756:
600:
435:
431:
427:
6473:. Harvard-Smithsonian Center for Astrophysics. Release 2013-06
4802:"Composition and Chemistry of the Neutral Atmosphere of Venus"
2442:
Listening for extraterrestrial signals indicating intelligence
1611:, in a distant star system. The molecule was found around the
588:
as a way to stimulate scientific dialogue at a meeting on the
10488:
10418:
9871:
9743:
7924:
The Living Universe: NASA And the Development of Astrobiology
7426:"Searching for ET: Hawking to look for extraterrestrial life"
7292:"Did the Wow! signal come from this star? | Space | EarthSky"
3452:
3313:
1597:
1596:
structure") that could be created naturally, and rapidly, by
1303:
1296:
1259:
1223:
1037:
439:
408:
159:
96:
6057:"My God, it's full of planets! They should have sent a poet"
5589:
5428:"NASA Researchers: DNA Building Blocks Can Be Made in Space"
4994:
4098:"100 Billion Alien Planets Fill Our Milky Way Galaxy: Study"
1667:
1286:
are the most likely places in the Solar System to find life.
948:
The first basic requirement for life is an environment with
395:
If extraterrestrial life exists, it could range from simple
9818:
8398:
5997:
5796:"Searching for Signs of Intelligent Life: Technosignatures"
5462:"Discovery: Cosmic Dust Contains Organic Matter from Stars"
5431:
5184:
5053:
4905:
4799:
3128:. Translated by Germain Heron. Routledge. pp. 111â118.
2943:
For the purpose of this 1 in 5 statistic, "Sun-like" means
2845:
2542:
2494:
2486:
2466:
2441:
1891:
1645:
1321:
1275:
1094:
791:= the fraction of planets with life that evolves to become
266:
92:
11860:
6599:. The New Middle Ages. Palgrave Macmillan US. p. 83.
6469:
Aguilar, David A.; Pulliam, Christine (25 February 2013).
6197:"Prevalence of Earth-size planets orbiting Sun-like stars"
6114:
5366:
4497:"Atmosphere - Planets, Composition, Pressure | Britannica"
2630:, in which they claim that Earth-like life is rare in the
1302:
The inner Solar System is likely devoid of life. However,
11742:
Archaeology, Anthropology, and Interstellar Communication
9914:
Astrobiology Science and Technology for Exploring Planets
7453:"Should We Call the Cosmos Seeking ET? Or Is That Risky?"
5940:"NASA Extends Planet-Hunting Kepler Mission Through 2016"
5890:"Major Discovery: New Planet Could Harbor Water and Life"
5817:
4561:
Daniel, Isabelle; Oger, Philippe; Winter, Roland (2006).
4348:
3880:
Burchell, M. J. (2006). "W(h)ither the Drake equation?".
3859:
2490:
2269:
1121:
1117:
1116:
and later evolved to its current form, where some of the
1069:
1033:
1029:
167:
7817:
Evolving the Alien: The Science of Extraterrestrial Life
7342:
Rare Earth: Why Complex Life is Uncommon in the Universe
4751:
3982:
Marcy, G.; Butler, R.; Fischer, D.; et al. (2005).
3933:
Evolving the Alien: The Science of Extraterrestrial Life
3436:"Scientists in US are urged to seek contact with aliens"
2761:
limitations lessened since the 1990s with the advent of
2733:
are a common way to depict extraterrestrials in fiction.
2623:
Rare Earth: Why Complex Life is Uncommon in the Universe
2314:
showed that neither water nor oxygen was present in the
2284:
Artificial Martian channels, depicted by Percival Lowell
4236:
4132:"The Flip Side of Optimism About Life on Other Planets"
4042:
2680:
in West Virginia in the United States and the 64-meter
1820:
that may be conducive to life, narrowing the search to
1076:
the most abundant of those elements is silicon, in the
8066:
Roth, Christopher F. (2005). Debbora Battaglia (ed.).
6049:
5343:"Catalog of Earth Microbes Could Help Find Alien Life"
4692:
2190:. Tycho could not make sense of his observations, but
1459:
hold the potential for hosting primitive life such as
1204:
Harsh environmental conditions on Earth harboring life
11825:
10048:
9137:
Potential cultural impact of extraterrestrial contact
7267:"LECTURE 4: MODERN THOUGHTS ON EXTRATERRESTRIAL LIFE"
6660:
Life's Origin: The Beginnings of Biological Evolution
6586:
6358:"One Star Over, a Planet That Might Be Another Earth"
6195:
Petigura, E. A.; Howard, A. W.; Marcy, G. W. (2013).
5985:"NASA Kepler Results Usher in a New Era of Astronomy"
5479:
3930:(2002). "Chapter 6: What does a Martian look like?".
3827:"Chapter 3 â Philosophy: "Solving the Drake Equation"
2806:
against potentially hazardous extraterrestrial life.
1965:
Potential cultural impact of extraterrestrial contact
1607:
reported the detection of a specific sugar molecule,
1603:
In August 2012, and in a world first, astronomers at
1393:. This special context encourages speculations about
824:
612:
7987:
Lonely Planets: The Natural Philosophy of Alien Life
7677:
7675:
5289:"NASA's Next Mars Rover to Land at Huge Gale Crater"
5132:
4872:
Chang, Kenneth; Stirone, Shannon (8 February 2021).
2139:. He proposed the idea that life exists everywhere.
1306:
is still of interest to astrobiologists, as it is a
984:
Life on Earth requires water in a liquid state as a
780:= the fraction of planets that actually support life
418:, the universe was initially too hot to allow life.
158:, in the 15th century, acknowledged the possibility
7981:, vol. 319, no. 3 (September 2018), pp. 94â99.
7105:
7084:
Worlds in the Making: The Evolution of the Universe
6268:"Milky Way may host billions of Earth-size planets"
6194:
2702:
American Association for the Advancement of Science
2525:(UFOs) would be spaceships from alien species, and
1856:in the Milky Way possibly number in the trillions.
1242:found on the ocean floor are known to support many
1192:. The amount of energy available would also affect
1104:. Life is generally considered to be a product of
537:gives enough time for a long process analog to the
8154:
8022:
7921:
5983:Harrington, J. D.; Johnson, M. (4 November 2013).
3981:
3735:
3603:Gonzalez, Guillermo; Richards, Jay Wesley (2004).
3365:
3363:
2999:
872:
702:
9434:Habitability of F-type main-sequence star systems
9424:Habitability of K-type main-sequence star systems
8517:Habitability of F-type main-sequence star systems
8507:Habitability of K-type main-sequence star systems
8006:Other Worlds: The Search for Life in the Universe
7672:
6838:Monthly Notices of the Royal Astronomical Society
6656:
6301:Monthly Notices of the Royal Astronomical Society
5982:
5863:
5716:Peter, Jonah S.; et al. (14 December 2023).
5455:
5453:
4608:Dong, Hailiang; Yu, Bingsong (1 September 2007).
3251:"The Hot Spring Hypothesis for an Origin of Life"
3123:
2641:As for the possible risks, theoretical physicist
11885:
11588:Communication with extraterrestrial intelligence
8804:Communication with extraterrestrial intelligence
8114:Communication with Extraterrestrial Intelligence
7702:"Why the French state has a team of UFO hunters"
6583:(pp 161â168). Springer International Publishing.
6108:
5905:
5903:
4560:
3742:. Art of Mentoring Series. Basic Books. p.
3738:Stephen Hawking's universe: the cosmos explained
3602:
3208:Shibuya, Takazo; Takai, Ken (16 November 2022).
1914:, it is too massive to be a planet and may be a
11550:
9359:Search for extraterrestrial intelligence (SETI)
8094:
7743:
6930:Library of Congress, Washington, D.C. 20540 USA
6779:Library of Congress, Washington, D.C. 20540 USA
6202:Proceedings of the National Academy of Sciences
6188:
5715:
5507:
5373:Proceedings of the National Academy of Sciences
4355:The Limits of Organic Life in Planetary Systems
3375:"So Many Earth-Like Planets, So Few Telescopes"
3360:
2828:Five-hundred-meter Aperture Spherical Telescope
2089:supported cosmic pluralism on the basis of the
6988:"The British Association Meeting at Edinburgh"
6652:
6650:
6468:
6462:
5834:
5676:
5450:
4902:"NASA Asks: Will We Know Life When We See It?"
4900:Cofield, Calla; Chou, Felicia (25 June 2018).
4460:
4164:
3645:"Life in Our Solar System? Meet the Neighbors"
1948:
1910:, although according to most definitions of a
11536:
10034:
9188:
8209:
7532:
7497:
7469:
7444:
5900:
5040:
4893:
4090:
3975:
3819:
3733:
3525:"When Did Life First Emerge in the Universe?"
2812:United Nations Office for Outer Space Affairs
2669:, announced a well-funded effort, called the
1499:by studying planetary surfaces and examining
376:
47:
9339:List of microorganisms tested in outer space
7806:
7773:. Hanover: University Press of New England.
7417:
7339:
6866:
6827:
6382:
6349:
5643:
5334:
5306:
5280:
4956:
4954:
4952:
4871:
4865:
4357:. The National Academies Press. p. 74.
4120:
3922:
3802:
3706:
3638:
3636:
3634:
3632:
3630:
3628:
3626:
3249:Damer, Bruce; Deamer, David (1 April 2020).
3207:
1771:typical of young stars, surrounded by dusty
195:search for extraterrestrial intelligent life
9112:History of the extraterrestrial life debate
8809:Gauss's Pythagorean right triangle proposal
7837:The Extraterrestrial Life Debate, 1750â1900
7558:"The French anti-UFO Municipal Law of 1954"
7535:"The weird aliens of early science fiction"
7319:"The Cosmos Might Be Mostly Devoid of Life"
7316:
6647:
6504:The Extraterrestrial Life Debate, 1750â1900
6005:The Astrophysical Journal Supplement Series
5881:
5709:
5425:
5419:
5101:
5099:
5068:
4925:
4919:
4899:
4654:"The history of life at hydrothermal vents"
3734:Filkin, David; Hawking, Stephen W. (1998).
3665:
3642:
3248:
3113:. University of Notre Dame. pp. 26â27.
3098:. University of Notre Dame. pp. 14â16.
3021:
1955:History of the extraterrestrial life debate
1812:discovered within its star's habitable zone
1694:project to search for alien communications.
1097:were incompatible with carbon based life.
11543:
11529:
10041:
10027:
9764:Enceladus Life Signatures and Habitability
9195:
9181:
8427:Planetary habitability in the Solar System
8216:
8202:
7920:Dick, Steven J.; Strick, James E. (2004).
7919:
7450:
7139:"Life's Working Definition: Does It Work?"
7087:. trans. H. Borns. Harper & Brothers.
6573:
6494:
6409:
5950:
4963:"Experts: Little Evidence of Life on Mars"
4444:"Aliens may be more like us than we think"
3988:Progress of Theoretical Physics Supplement
3574:
2991:
2971:
2962:
2953:
2937:
1266:Planetary habitability in the Solar System
1260:Planetary habitability in the Solar System
514:
383:
369:
253:Planetary habitability in the Solar System
9951:European Astrobiology Network Association
8223:
7984:
7951:
7528:
7526:
7080:
7019:
6958:
6891:
6857:
6638:
6592:
6429:
6331:
6313:
6242:
6232:
6214:
6128:
6091:
6016:
5912:"Interactive Extra-solar Planets Catalog"
5909:
5789:
5787:
5785:
5783:
5735:
5610:
5513:
5402:
5392:
4949:
4728:
4710:
4677:
4625:
4429:
4427:
4325:
4315:
4250:
4178:
4057:
4036:
3999:
3956:
3770:Chemical Evolution and the Origin of Life
3766:
3707:Steiger, Brad; White, John, eds. (1986).
3623:
3578:Panspermia: A Promising Field of Research
3568:
3545:
3466:
3335:
3290:
3225:
2780:archetype once used in works of fiction.
1668:Search for extraterrestrial intelligences
403:similar to animals or plants, to complex
11904:Search for extraterrestrial intelligence
11593:Search for extraterrestrial intelligence
9444:List of potentially habitable exoplanets
8854:Search for extraterrestrial intelligence
8522:List of potentially habitable exoplanets
8152:
8043:
7792:. United States: Pearson. pp. 3â4.
7555:
7399:Diamond, Jared M. (2006). "Chapter 12".
7207:
6897:
6169:
5566:
5360:
5105:
5096:
3959:"About those 2 trillion new galaxies..."
3879:
3873:
3773:. trans. Terence N. Mitchell. Springer.
3609:. Regnery Publishing. pp. 343â345.
3522:
3065:
2725:
2279:
2146:
1979:
1799:
1796:List of potentially habitable exoplanets
1677:
1674:Search for extraterrestrial intelligence
1588:("amorphous organic solids with a mixed
1482:
1478:
1269:
1238:forming spontaneously. For example, the
755:= the fraction of those stars that have
590:search for extraterrestrial intelligence
9862:Living Interplanetary Flight Experiment
8659:Living Interplanetary Flight Experiment
8161:. Syracuse: Syracuse University Press.
8020:
8003:
7787:
7699:
7623:
7398:
6982:
6872:
6742:
6740:
6175:
5793:
5569:"Sugar Found In Space: A Sign of Life?"
5340:
5046:
4990:
4988:
4960:
4126:
3847:
3369:
3214:Progress in Earth and Planetary Science
3153:
3143:. University of Notre Dame. p. 67.
2783:
2000:were based on mythology. Scholars from
1890:, which is about twice the mass of the
580:In 1961, astronomer and astrophysicist
14:
11886:
7744:Aguilera MochĂłn, Juan Antonio (2016).
7718:
7604:
7523:
7340:Ward, Peter; Brownlee, Donald (2000).
7108:"The Face on Mars: Fact & Fiction"
7106:Nola Taylor Tillman (20 August 2012).
7037:
6798:
6544:
6528:Wiker, Benjamin D. (4 November 2002).
5780:
5253:
5178:
5074:
4607:
4424:
4292:"The universal nature of biochemistry"
3027:
2321:As a consequence of the belief in the
2202:, clarified the final doubts, and the
2142:
2040:(earth, water, fire and air), and the
2023:thought that the cosmos was made from
11524:
10022:
9852:Biological Oxidant and Life Detection
9176:
8560:Biological Oxidant and Life Detection
8197:
8110:
7942:
7853:
7834:
7766:
7626:"Is China The Next Space Superpower?"
7475:
7451:Borenstein, Seth (13 February 2015).
7172:
6550:
6527:
6500:
6355:
5976:
5910:Schneider, Jean (10 September 2011).
5768:from the original on 15 December 2023
5697:from the original on 14 December 2023
5682:
5649:
4647:
4645:
4463:International Journal of Astrobiology
3882:International Journal of Astrobiology
3433:
3138:
3108:
3093:
2997:
2653:, which didn't turn out well for the
1783:
1455:, and other planets and moons in the
1182:International Journal of Astrobiology
75:(more unsolved problems in astronomy)
10001:
9429:Habitability of yellow dwarf systems
9414:Habitability of neutron star systems
8512:Habitability of yellow dwarf systems
8497:Habitability of neutron star systems
8257:Viking lander biological experiments
8131:
8070:. Durham, NC: Duke University Press.
8065:
7900:
7881:
7872:
7478:"Scientist: 'Try to contact aliens'"
7423:
6737:
6579:David A. Weintraub (2014). "Islam,"
6265:
5937:
5887:
5664:from the original on 5 December 2023
5459:
5312:
5286:
4985:
4289:
3936:. Hoboken, NJ: John Wiley and Sons.
3841:
3713:. Health Research Books. p. 3.
3407:
3203:
3201:
2485:, this discipline is studied by the
2370:region of Mars, first imaged by the
2169:observations provided limited data.
1644:, a possible chemical essential for
1537:In November 2011, NASA launched the
1401:
931:
478:There is an area around a star, the
11609:List of interstellar radio messages
9404:Habitability of binary star systems
8487:Habitability of binary star systems
8462:Catalog of Nearby Habitable Systems
7719:Jeffay, Nathan (10 December 2020).
6581:Religions and Extraterrestrial Life
5683:Chang, Kenneth (14 December 2023).
5426:Steigerwald, John (8 August 2011).
5276:. spacetoday.net. 19 February 2005.
4936:University of California, Riverside
4926:Nightingale, Sarah (25 June 2018).
4290:Pace, Norman R. (20 January 2001).
3957:Macrobert, Alan (13 October 2016).
3066:Pickrell, John (4 September 2006).
2030:Eventually two groups emerged, the
1969:
1738:The atmosphere of Earth is rich in
1144:to multicellular organisms through
233:This article is one of a series on:
24:
11413:Nexus for Exoplanet System Science
9966:Nexus for Exoplanet System Science
9409:Habitability of natural satellites
9334:Hypothetical types of biochemistry
9122:Nexus for Exoplanet System Science
8965:Hypothetical types of biochemistry
8492:Habitability of natural satellites
7858:. University of Notre Dame Press.
7736:
7700:Bockman, Chris (4 November 2014).
7624:Wheeler, Michelle (14 July 2017).
7509:University of California, Berkeley
7476:Ghosh, Pallab (12 February 2015).
7461:. Associated Press. Archived from
7187:10.1023/B:QUAS.0000015542.28438.41
6663:. University of California Press.
5254:Berger, Brian (16 February 2005).
5075:Gannon, Megan (28 February 2014).
4642:
4349:National Research Council (2007).
3434:Ghosh, Pallab (12 February 2015).
3316:"Microbial Life in Volcanic Lakes"
3176:10.1016/b978-0-444-53802-4.00185-8
2894:Hypothetical types of biochemistry
2548:Looking beyond the psudosciences,
2226:, which trialed and executed him.
1026:hypothetical types of biochemistry
938:Hypothetical types of biochemistry
553:, it would be improbable for life
25:
11950:
11313:Atomic and molecular astrophysics
10050:Molecules detected in outer space
9946:Center for Life Detection Science
9867:Mars Astrobiology Explorer-Cacher
9419:Habitability of red dwarf systems
8502:Habitability of red dwarf systems
8177:
7533:Zaria Gorvett (22 October 2023).
7374:"Hawking warns over alien beings"
6356:Chang, Kenneth (24 August 2016).
5599:The Astrophysical Journal Letters
5315:"Mars rover aims for deep crater"
5047:Webster, Guy (27 February 2014).
3198:
2772:, the first recorded claim of an
2379:
2198:a short time later, perfected by
1336:As mentioned, the gas giants and
357:F-type main-sequence star systems
347:K-type main-sequence star systems
53:Could life have arisen elsewhere?
11871:
11859:
11847:
11835:
11808:
11797:
11796:
11503:
11491:
11479:
11468:
11467:
10274:
10265:
10256:
10000:
9989:
9988:
9971:Ocean Worlds Exploration Program
9804:Life Investigation For Enceladus
9324:Extraterrestrial sample curation
9202:
8654:Life Investigation For Enceladus
8104:Intelligent Life in the Universe
7712:
7693:
7654:
7636:
7617:
7605:Kluger, Jeffrey (2 March 2020).
7598:
7580:
7549:
7392:
7366:
7333:
7317:Paul Davies (1 September 2016).
7310:
7284:
7259:
7250:
7236:
7201:
7166:
7157:
7131:
7122:
7099:
7081:Arrhenius, Svante (March 1908).
7074:
7031:
6976:
6965:Annalen der Chemie und Pharmacie
6952:
6943:
6918:
6901:Life on Mars; The Complete Story
6821:
6792:
6767:
6758:
6749:
6711:
6702:
6693:
6684:
6629:
6620:
6521:
6485:
6333:10.1111/j.1365-2966.2012.21009.x
6287:
6259:
6075:
5917:Extrasolar Planets Encyclopaedia
5650:Green, Jaime (5 December 2023).
5460:Chow, Denise (26 October 2011).
5341:Cofield, Calla (30 March 2015).
5109:Life on Mars; The Complete Story
4104:. 2 January 2013. Archived from
3666:Vicky Stein (16 February 2023).
3643:Pat Brennan (10 November 2020).
3575:Rampelotto, P. H. (April 2010).
2998:Frank, Adam (31 December 2020).
2904:Outline of extraterrestrial life
2414:
2403:
2394:
1648:as we know it, as well as other
1507:were discovered in a meteorite,
592:(SETI). The Drake equation is a
306:Potentially habitable exoplanets
224:
11438:Polycyclic aromatic hydrocarbon
9909:Astrobiology Society of Britain
9784:Explorer of Enceladus and Titan
9439:Habitable zone for complex life
8189:European Astrobiology Institute
8008:. New York: A Touchstone Book.
7683:"France opens up its UFO files"
7556:Matignon, Louis (29 May 2019).
7230:10.1016/j.actaastro.2009.12.011
6873:Wallace, Alfred Russel (1907).
6553:The Arabian Nights: A Companion
6266:Khan, Amina (4 November 2013).
6176:Sanders, R. (4 November 2013).
5991:
5931:
5828:
5810:
5583:
5560:
5313:Amos, Jonathan (22 July 2011).
5274:"NASA denies Mars life reports"
5266:
5247:
5221:
5126:
4961:Crenson, Matt (6 August 2006).
4843:
4793:
4784:
4745:
4686:
4679:10.1016/j.earscirev.2021.103602
4627:10.18814/epiiugs/2007/v30i3/003
4601:
4554:
4514:
4489:
4454:
4436:
4415:
4406:
4397:
4388:
4379:
4342:
4283:
4230:
4221:
4212:
4203:
4158:
3950:
3916:
3796:
3787:
3760:
3727:
3700:
3691:
3682:
3659:
3596:
3539:
3516:
3507:
3485:10.1016/j.actaastro.2010.10.012
3446:
3427:
3401:
3307:
3242:
3033:"Are We Alone in the Universe?"
2899:Life origination beyond planets
2354:(1879) and, somewhat later, by
2275:
2081:. Medieval Muslim writers like
1859:The nearest known exoplanet is
890:Based on observations from the
11914:Unsolved problems in astronomy
9794:Journey to Enceladus and Titan
8644:Journey to Enceladus and Titan
7424:Katz, Gregory (20 July 2015).
6799:Parkyn, Joel L. (April 2019).
6507:. Courier Dover Publications.
3803:Morgan Kelly (26 April 2012).
3408:Mann, Adam (1 December 2020).
3162:, Elsevier, pp. 429â472,
3147:
3132:
3117:
3102:
3087:
3059:
2770:Barney and Betty Hill incident
2541:or weather phenomenons, or as
2152:Galileo before the Holy Office
950:non-equilibrium thermodynamics
95:which does not originate from
13:
1:
11363:Extraterrestrial liquid water
9842:Astrobiology Field Laboratory
9394:Extraterrestrial liquid water
8777:Berkeley SETI Research Center
8477:Extraterrestrial liquid water
5287:Chow, Dennis (22 July 2011).
4778:10.1016/S0032-0633(02)00144-7
4699:The Planetary Science Journal
3710:Other Worlds, Other Universes
2985:
2715:
2154:, a 19th-century painting by
2009:. They had not developed the
1906:, about 29 times the mass of
1871:) from Earth in the southern
1810:terrestrial extrasolar planet
1560:found on Antarctica, finding
1556:In August 2011, NASA studied
1293:extraterrestrial intelligence
525:Extraterrestrial intelligence
69:evolution of intelligent life
48:Unsolved problem in astronomy
39:Extraterrestrial intelligence
11909:Unsolved problems in biology
9976:Spanish Astrobiology Centerâ
9384:Circumstellar habitable zone
9097:Extraterrestrials in fiction
8970:Interplanetary contamination
8467:Circumstellar habitable zone
8351:(unusual light fluctuations)
8343:(unusual light fluctuations)
8335:(unusual light fluctuations)
8004:Lemnick, Michael T. (1998).
7271:The University of Antarctica
7141:. NASA. 2002. Archived from
6418:Astronomy & Astrophysics
6390:"DENIS-P J082303.1-491201 b"
5857:10.1016/0019-1035(80)90253-5
5018:10.1126/science.273.5277.924
4269:10.1088/0004-637X/715/2/1050
3829:. SETI League. December 2002
3328:10.1007/978-3-642-36833-2_23
2884:First contact (anthropology)
2722:Extraterrestrials in fiction
2626:. In it, they discussed the
2363:extraterrestrials in fiction
2156:Joseph-Nicolas Robert-Fleury
2124:, it became associated with
1816:Some astronomers search for
1132:. Life on Earth jumped from
944:Water § Effects on life
480:circumstellar habitable zone
202:extraterrestrials in fiction
32:Extraterrestrials in fiction
7:
11552:Interstellar communications
10594:Protonated hydrogen cyanide
9961:NASA Astrobiology Institute
8955:Extraterrestrial hypothesis
8153:Tumminia, Diana G. (2007).
7958:. New York: A Dutton Book.
6448:10.1051/0004-6361/201321871
5938:Wall, Mike (4 April 2012).
5888:Than, Ker (24 April 2007).
5567:Ker Than (30 August 2012).
5156:10.1126/science.194.4260.99
4758:Planetary and Space Science
4528:Planetary and Space Science
4076:10.1088/0004-637X/764/1/105
3848:Aguirre, L. (1 July 2008).
2866:
2523:unidentified flying objects
2109:Great Library of Alexandria
1949:History and cultural impact
1708:interstellar communications
1190:non-green photosynthesisers
10:
11955:
11919:Astronomical controversies
9809:Mars sample return mission
8669:Mars sample-return mission
7952:Goldsmith, Donald (1997).
7854:Crowe, Michael J. (2008).
7835:Crowe, Michael J. (1986).
7128:Aguilera Mochon, pp. 10â11
6657:J. William Schopf (2002).
6501:Crowe, Michael J. (1999).
5754:10.1038/s41550-023-02160-0
5629:10.1088/2041-8205/757/1/L4
4853:. University of Washington
4433:Aguilera MochĂłn, pp. 61â66
4421:Aguilera MochĂłn, pp. 42â43
4412:Aguilera MochĂłn, pp. 58â59
4385:Aguilera MochĂłn, pp. 43â49
4351:"6.2.2: Nonpolar Solvents"
4197:10.1038/s41550-023-02014-9
3227:10.1186/s40645-022-00510-6
3139:Crowe, Michael J. (2008).
3124:Nicholas of Cusa. (1954).
3109:Crowe, Michael J. (2008).
3094:Crowe, Michael J. (2008).
2787:
2763:computer-generated imagery
2719:
2620:published a book entitled
2383:
1973:
1958:
1952:
1904:DENIS-P J082303.1â491201 b
1826:multiple planetary systems
1793:
1787:
1717:Organizations such as the
1671:
1405:
1263:
1120:tasks were transferred to
941:
935:
518:
509:even the most hostile ones
216:
186:, acidic hot springs, and
107:, possibly bringing forth
36:
29:
11791:
11728:
11667:
11601:
11558:
11462:
11353:Earliest known life forms
11348:Diffuse interstellar band
11288:
11208:
11133:
11024:
10959:
10899:
10827:
10819:Protonated cyanoacetylene
10733:
10627:
10589:Protonated carbon dioxide
10549:Hydromagnesium isocyanide
10497:
10283:
10254:
10065:
10056:
9984:
9899:
9887:Terrestrial Planet Finder
9832:
9731:
9693:
9677:
9645:
9562:
9471:
9462:
9372:
9309:Earliest known life forms
9276:
9210:
9057:
8993:
8932:
8887:
8745:
8545:
8450:
8422:Earliest known life forms
8414:
8367:
8324:
8297:
8290:
8231:
8051:. New York: Basic Books.
8021:Michaud, Michael (2006).
7985:Grinspoon, David (2003).
7955:The Hunt for Life on Mars
7788:Bennett, Jeffrey (2017).
7752:] (in Spanish). RBA.
6559:. p. 204 & 209.
6035:10.1088/0067-0049/206/1/5
4821:10.1007/s11214-017-0438-5
4548:10.1016/j.pss.2006.02.006
4475:10.1017/S1473550417000349
4239:The Astrophysical Journal
4046:The Astrophysical Journal
3902:10.1017/S1473550406003107
3767:Rauchfuss, Horst (2008).
3688:Aguilera Mochon, pp. 9â10
3523:Avi Loeb (4 April 2021).
2852:In 2020, chairman of the
2700:) at a convention of the
2507:hypothetical technologies
2224:Venetian Holy Inquisition
1518:An experiment on the two
954:thermodynamic equilibrium
603:. The Drake equation is:
11571:Breakthrough Initiatives
11398:Ironâsulfur world theory
11393:Photodissociation region
11096:Methyl-cyano-diacetylene
9919:Breakthrough Initiatives
8787:Breakthrough Initiatives
7947:. Berlin: Berlin Verlag.
7901:Dick, Steven J. (2001).
7882:Dick, Steven J. (1996).
7873:Dick, Steven J. (1984).
7750:The non-terrestrial life
6949:Aguilera Mochon, pp. 8â9
6593:Gabrovsky, A.N. (2016).
4567:Chemical Society Reviews
2930:
2745:On the Origin of Species
2671:Breakthrough Initiatives
2312:William Wallace Campbell
467:, for example â between
11473:Category:Astrochemistry
11063:, fullerene, buckyball)
10750:Cyanobutadiynyl radical
10725:Silicon-carbide cluster
10715:Protonated formaldehyde
9580:Mars Science Laboratory
9399:Galactic habitable zone
8891:extraterrestrial beings
8482:Galactic habitable zone
8132:Ward, Peter D. (2005).
7767:Baird, John C. (1987).
6898:Chambers, Paul (1999).
6557:Tauris Parke Paperbacks
6440:2013A&A...556A.133S
6234:10.1073/pnas.1319909110
6182:newscenter.berkeley.edu
5394:10.1073/pnas.1106493108
5106:Chambers, Paul (1999).
4851:"What Is Astrobiology?"
4770:2003P&SS...51..105A
4540:2007P&SS...55..370A
3156:"Planetary Atmospheres"
2264:. At the height of the
1884:least massive exoplanet
1804:Artist's impression of
1732:artificial intelligence
1539:Mars Science Laboratory
1249:origin of life on Earth
952:, which means that the
515:Likelihood of existence
450:may have formed in the
446:emerged, and the first
401:multicellular organisms
311:Galactic habitable zone
179:atmospheric composition
11934:Scientific speculation
11486:Outer space portal
11328:Circumstellar envelope
10293:Aluminium(I) hydroxide
10203:Phosphorus mononitride
10080:Aluminium monofluoride
10075:Aluminium monochloride
9759:Enceladus Life Finderâ
9739:Breakthrough Enceladus
9263:Planetary oceanography
9039:Planetarium hypothesis
9029:HartâTipler conjecture
9014:Dark forest hypothesis
9004:Aestivation hypothesis
8723:Venus In Situ Explorer
8527:Planetary habitability
8316:(misidentified quasar)
8308:(misidentified pulsar)
7163:Aguilera Mochon, p. 10
6859:10.1093/mnras/63.8.488
6551:Irwin, Robert (2003).
6296:"Nomads of the Galaxy"
5134:Preliminary Results".
4227:Aguilera MochĂłn, p. 51
4218:Aguilera MochĂłn, p. 58
4209:Aguilera MochĂłn, p. 42
3807:. Princeton University
3793:Aguilera MochĂłn, p. 66
3160:Treatise on Geophysics
3154:Catling, D.C. (2015),
2734:
2323:spontaneous generation
2285:
2158:
1989:
1924:planetary habitability
1900:NASA Exoplanet Archive
1882:As of March 2014, the
1834:Kepler space telescope
1813:
1695:
1513:rock ejected from Mars
1491:Scientists search for
1488:
1287:
892:Hubble Space Telescope
874:
737:= the average rate of
704:
594:probabilistic argument
485:planetary habitability
420:15 million years later
11929:Biology controversies
11924:Biological hypotheses
11899:Interstellar messages
11763:Extraterrestrial life
11690:Sebastian von Hoerner
11659:Voyager Golden Record
11383:Interplanetary medium
11358:Extraterrestrial life
10996:Octatetraynyl radical
10614:Tricarbon monosulfide
10161:Magnesium monohydride
9934:Breakthrough Starshot
9534:Lunar Micro Ecosystem
9454:Superhabitable planet
9319:Extraterrestrial life
9142:Post-detection policy
9044:Rare Earth hypothesis
8869:Voyager Golden Record
8762:Allen Telescope Array
8597:Enceladus Life Finder
8532:Superhabitable planet
8225:Extraterrestrial life
8049:The Science of Aliens
7943:Fasan, Ernst (1970).
7321:. Scientific American
7175:Qualitative Sociology
7060:10.1089/ast.2011.0790
6960:Berzelius, Jöns Jacob
6904:. London: Blandford.
6879:. London: Macmillan.
6746:Aguilera Mochon, p. 8
5571:. National Geographic
5231:. ESA. Archived from
5207:10.1089/ast.2007.0153
5112:. London: Blandford.
4809:Space Science Reviews
4658:Earth-Science Reviews
4317:10.1073/pnas.98.3.805
3527:. Scientific American
3275:10.1089/ast.2019.2045
2909:Quiet and loud aliens
2752:, which proposed the
2729:
2628:Rare Earth hypothesis
2596:habitability criteria
2352:Hermann von Helmholtz
2283:
2175:Copernican Revolution
2150:
1983:
1920:extragalactic planets
1828:as of 24 July 2024).
1803:
1725:, and now search for
1681:
1654:microbial communities
1636:, moon of the planet
1605:Copenhagen University
1486:
1479:Search for basic life
1273:
1142:unicellular organisms
875:
705:
570:Rare Earth hypothesis
177:When considering the
81:Extraterrestrial life
57:requirements for life
11614:A Message from Earth
11581:Breakthrough Message
11510:Chemistry portal
11498:Astronomy portal
11444:RNA world hypothesis
11428:PAH world hypothesis
11121:Heptatrienyl radical
11053:Buckminsterfullerene
10941:Methylcyanoacetylene
10449:Silicon carbonitride
10424:Methylidynephosphane
10390:Magnesium isocyanide
10298:Aluminium isocyanide
10100:Carbon monophosphide
9941:Carl Sagan Institute
9929:Breakthrough Message
9769:Enceladus Orbilander
9504:Biosatellite program
9354:Planetary protection
9238:Evolutionary biology
9228:Atmospheric sciences
9132:Planetary protection
9019:Firstborn hypothesis
9009:Berserker hypothesis
8980:Mediocrity principle
8797:Breakthrough Message
8415:Life in the Universe
8184:Astrobiology at NASA
8138:. New York: Viking.
8111:Sagan, Carl (1973).
8029:. Berlin: Springer.
7790:Life in the universe
7746:La vida no terrestre
7465:on 14 February 2015.
7403:. Harper Perennial.
6540:on 10 February 2003.
4448:University of Oxford
3850:"The Drake Equation"
3126:Of Learned Ignorance
3031:(18 November 2013).
2839:Russian space agency
2804:planetary protection
2790:Planetary protection
2784:Government responses
2678:Green Bank Telescope
2539:astronomical objects
2344:Jöns Jacob Berzelius
2248:, the discoverer of
2083:Fakhr al-Din al-Razi
1961:History of astronomy
1773:protoplanetary disks
1684:Green Bank Telescope
1528:Ames Research Center
1438:atmospheric sciences
1158:convergent evolution
1083:atmospheric pressure
926:Samuel L. Braunstein
822:
795:life (civilisations)
722:interplanetary space
610:
563:mediocrity principle
559:Copernican principle
531:size of the universe
471:in a process called
352:Yellow dwarf systems
337:Neutron star systems
239:Life in the universe
11710:Linda Salzman Sagan
11619:Across the Universe
11576:Breakthrough Listen
11388:Interstellar medium
11368:Forbidden mechanism
11181:Hydrogen isocyanide
10871:Hexatriynyl radical
10454:c-Silicon dicarbide
10359:Hydrogen isocyanide
10223:Silicon monosulfide
10198:Phosphorus monoxide
10166:Methylidyne radical
10125:Fluoromethylidynium
10085:Aluminium(II) oxide
9924:Breakthrough Listen
8945:Directed panspermia
8924:Reptilian humanoids
8792:Breakthrough Listen
8772:Arecibo Observatory
8718:Titan Mare Explorer
8291:Signals of interest
8251:Murchison meteorite
8239:Shergotty meteorite
8014:1998owsl.book.....L
7978:Scientific American
7726:The Times of Israel
7350:2000rewc.book.....W
7222:2011AcAau..68....2A
7052:2012AsBio..12..946D
7004:1871Natur...4..261.
6850:1903MNRAS..63..488E
6324:2012MNRAS.423.1856S
6225:2013PNAS..11019273P
6209:(48): 19273â19278.
6147:10.1038/nature10684
6139:2012Natur.481..167C
6102:2013sf2a.conf..555S
6027:2013ApJS..206....5T
5849:1980Icar...42..149W
5746:2024NatAs...8..164P
5621:2012ApJ...757L...4J
5538:10.1038/nature10542
5530:2011Natur.479...80K
5385:2011PNAS..10813995C
5379:(34): 13995â13998.
5199:2007AsBio...7..545B
5148:1976Sci...194...99K
5010:1996Sci...273..924M
4721:2020PSJ.....1...11Z
4670:2021ESRv..21703602G
4308:2001PNAS...98..805P
4261:2010ApJ...715.1050B
4189:2023NatAs...7..755W
4068:2013ApJ...764..105S
4018:10.1143/PTPS.158.24
4010:2005PThPS.158...24M
3962:Sky & Telescope
3894:2006IJAsB...5..243B
3590:2010LPICo1538.5224R
3477:2011AcAau..68.2114B
3414:Scientific American
3267:2020AsBio..20..429D
3168:2015trge.book..429C
3007:The Washington Post
2924:Uncontacted peoples
2854:Israel Space Agency
2846:French space agency
2754:theory of evolution
2535:top-secret aircraft
2511:science divulgation
2452:Robotic exploration
2302:Mars and its Canals
2296:published his book
2171:Nicolaus Copernicus
2161:By the time of the
2143:Early modern period
1896:most massive planet
1822:terrestrial planets
1752:chlorofluorocarbons
1692:Breakthrough Listen
1162:Simon Conway Morris
995:terrestrial planets
535:age of the universe
452:protoplanetary disk
405:alien intelligences
327:Binary star systems
11408:Molecules in stars
11378:Intergalactic dust
11323:Circumstellar dust
11265:Naphthalene cation
11200:Trihydrogen cation
11176:Hydrogen deuteride
11101:Methyltriacetylene
10936:Hexapentaenylidene
10755:E-Cyanomethanimine
10675:Cyclopropenylidene
10609:Tricarbon monoxide
10599:Silicon tricarbide
10569:Methylene amidogen
10559:Isothiocyanic acid
10474:Thioxoethenylidene
10434:Trihydrogen cation
10248:Titanium(II) oxide
10208:Potassium chloride
10187:Sulfur mononitride
10130:Helium hydride ion
10105:Carbon monosulfide
9754:Enceladus Explorer
9067:Ancient astronauts
8664:Mars Geyser Hopper
8592:Enceladus Explorer
8232:Events and objects
7594:. 14 October 2010.
7562:Space Legal Issues
7511:. 13 February 2015
7458:The New York Times
7432:. Associated Press
6725:on 13 October 2014
6491:Bennett, pp. 16-23
6362:The New York Times
5964:on 5 November 2013
5877:. 25 January 2006.
5690:The New York Times
5235:on 19 October 2012
4879:The New York Times
4730:10.3847/PSJ/ab7e2c
4501:www.britannica.com
4450:. 31 October 2017.
4137:The New York Times
4032:on 2 October 2008.
3380:The New York Times
3373:(6 January 2015).
3038:The New York Times
2837:, the head of the
2796:Outer Space Treaty
2735:
2527:ancient astronauts
2429:extrasolar planets
2316:Martian atmosphere
2286:
2159:
2038:classical elements
1990:
1861:Proxima Centauri b
1852:are included. The
1818:extrasolar planets
1814:
1784:Extrasolar planets
1696:
1489:
1372:. The space probe
1308:terrestrial planet
1288:
1240:hydrothermal vents
1236:chemical reactions
1226:escaping from the
1219:hydrothermal vents
1166:bilateral symmetry
1153:Cambrian explosion
967:hydrothermal vents
870:
700:
332:Natural satellites
319:Habitability of...
184:Hydrothermal vents
105:intelligent beings
67:How likely is the
11823:
11822:
11720:Aleksandr Zaitsev
11695:Nikolai Kardashev
11518:
11517:
11433:Pseudo-panspermia
11129:
11128:
11076:Cyanodecapentayne
11016:N-Methylformamide
10991:Methyldiacetylene
10916:Aminoacetonitrile
10886:Methyl isocyanate
10804:Methyl isocyanide
10685:Isocyanoacetylene
10665:Cyanoformaldehyde
10544:Hydrogen peroxide
10429:Potassium cyanide
10385:Magnesium cyanide
10338:Disilicon carbide
10333:Dicarbon monoxide
10140:Hydrogen fluoride
10135:Hydrogen chloride
10016:
10015:
9895:
9894:
9719:Rosalind Franklin
9632:Trace Gas Orbiter
9289:Allan Hills 84001
9268:Planetary science
9170:
9169:
8700:SpaceX Red Dragon
8615:Rosalind Franklin
8410:
8409:
8269:Allan Hills 84001
8263:Allan Hills 77005
8168:978-0-8156-0858-5
8145:978-0-670-03458-1
8124:978-0-262-19106-7
8100:Shklovskii, I. S.
8058:978-0-465-07315-3
8036:978-0-387-28598-6
7996:978-0-06-018540-4
7989:. HarperCollins.
7965:978-0-525-94336-5
7935:978-0-8135-3447-3
7912:978-0-521-79912-6
7893:978-0-521-34326-8
7865:978-0-268-02368-3
7846:978-0-521-26305-4
7827:978-0-09-187927-3
7799:978-0-13-408908-9
7780:978-0-87451-406-3
7759:978-84-473-8665-9
7410:978-0-06-084550-6
7359:978-0-387-98701-9
7298:. 2 December 2020
7210:Acta Astronautica
6911:978-0-7137-2747-0
6764:Bennet, pp. 30-32
6690:Bennet, pp. 24-27
6606:978-1-137-52391-4
6566:978-1-86064-983-7
6514:978-0-486-40675-6
6370:on 1 January 2022
6273:Los Angeles Times
6123:(7380): 167â169.
5495:. 26 October 2011
5119:978-0-7137-2747-0
5004:(5277): 924â930.
4372:978-0-309-10484-5
4173:(2023): 755â756.
4146:on 1 January 2022
4130:(3 August 2015).
4108:on 3 January 2013
3943:978-0-09-187927-3
3780:978-3-540-78822-5
3753:978-0-465-08198-1
3720:978-0-7873-1291-6
3616:978-0-89526-065-9
3549:(29 March 2012).
3461:(11): 2114â2129.
3455:Acta Astronautica
3389:on 1 January 2022
3347:978-3-642-36832-5
3185:978-0-444-53803-1
3047:on 1 January 2022
2879:Carbon chauvinism
2740:origin of mankind
2665:, along with the
2521:claims that many
2386:Space exploration
2262:Benjamin Franklin
2231:theory of gravity
2100:The House of Fame
2087:Muhammad al-Baqir
2071:Mahavideh Kshetra
2011:scientific method
1658:organic synthesis
1656:or drive complex
1650:organic molecules
1586:organic compounds
1584:contains complex
1578:organic molecules
1402:Scientific search
1364:, a tiny moon of
1312:greenhouse effect
1174:digestive systems
1106:natural selection
1022:chemical elements
932:Biochemical basis
502:stellar evolution
469:habitable planets
448:organic compounds
444:Planetary systems
414:According to the
393:
392:
342:Red dwarf systems
295:Life outside the
115:than humans. The
113:far more advanced
27:Life not on Earth
16:(Redirected from
11946:
11876:
11875:
11874:
11864:
11863:
11852:
11851:
11850:
11840:
11839:
11831:
11812:
11800:
11799:
11783:San Marino Scale
11753:Astrolinguistics
11685:Hans Freudenthal
11654:Teen Age Message
11644:Hello from Earth
11545:
11538:
11531:
11522:
11521:
11508:
11507:
11506:
11496:
11495:
11494:
11484:
11483:
11482:
11471:
11470:
11418:Organic compound
11318:Chemical formula
11223:Dihydroxyacetone
11171:Hydrogen cyanide
10856:Cyanodiacetylene
10710:Propadienylidene
10604:Thioformaldehyde
10479:Titanium dioxide
10444:Sodium hydroxide
10365:Hydrogen sulfide
10353:Hydrogen cyanide
10313:Carbonyl sulfide
10278:
10269:
10260:
10218:Silicon monoxide
10151:Hydroxyl radical
10063:
10062:
10043:
10036:
10029:
10020:
10019:
10004:
10003:
9992:
9991:
9469:
9468:
9364:Yamato meteorite
9197:
9190:
9183:
9174:
9173:
9147:San Marino Scale
9087:Brookings Report
9034:Neocatastrophism
8940:Cosmic pluralism
8914:Little green men
8889:Types of alleged
8814:Astrolinguistics
8403:
8395:
8394:(unknown origin)
8391:Fast radio burst
8387:
8379:
8360:
8359:(unknown origin)
8356:HD 164595 signal
8352:
8344:
8336:
8317:
8309:
8295:
8294:
8245:Nakhla meteorite
8218:
8211:
8204:
8195:
8194:
8172:
8160:
8149:
8128:
8107:
8091:
8085:
8081:
8079:
8071:
8062:
8040:
8028:
8017:
8000:
7969:
7948:
7939:
7927:
7916:
7897:
7878:
7869:
7850:
7831:
7803:
7784:
7763:
7731:
7730:
7716:
7710:
7709:
7697:
7691:
7690:
7689:. 22 March 2007.
7679:
7670:
7669:
7658:
7652:
7651:
7650:on 11 July 2019.
7646:. Archived from
7640:
7634:
7633:
7621:
7615:
7614:
7602:
7596:
7595:
7584:
7578:
7577:
7575:
7573:
7568:on 27 April 2021
7564:. Archived from
7553:
7547:
7546:
7544:
7542:
7530:
7521:
7520:
7518:
7516:
7501:
7495:
7494:
7492:
7490:
7473:
7467:
7466:
7448:
7442:
7441:
7439:
7437:
7421:
7415:
7414:
7396:
7390:
7389:
7387:
7385:
7370:
7364:
7363:
7337:
7331:
7330:
7328:
7326:
7314:
7308:
7307:
7305:
7303:
7288:
7282:
7281:
7279:
7277:
7263:
7257:
7254:
7248:
7240:
7234:
7233:
7205:
7199:
7198:
7170:
7164:
7161:
7155:
7154:
7152:
7150:
7135:
7129:
7126:
7120:
7119:
7117:
7115:
7103:
7097:
7096:
7078:
7072:
7071:
7035:
7029:
7028:
7023:
7012:10.1038/004261a0
6984:Thomson, William
6980:
6974:
6973:
6956:
6950:
6947:
6941:
6940:
6938:
6936:
6922:
6916:
6915:
6895:
6889:
6888:
6870:
6864:
6863:
6861:
6825:
6819:
6818:
6816:
6814:
6808:ore.exeter.ac.uk
6805:
6796:
6790:
6789:
6787:
6785:
6771:
6765:
6762:
6756:
6753:
6747:
6744:
6735:
6734:
6732:
6730:
6721:. Archived from
6715:
6709:
6706:
6700:
6697:
6691:
6688:
6682:
6681:
6679:
6677:
6654:
6645:
6642:
6636:
6633:
6627:
6624:
6618:
6617:
6615:
6613:
6590:
6584:
6577:
6571:
6570:
6548:
6542:
6541:
6536:. Archived from
6525:
6519:
6518:
6498:
6492:
6489:
6483:
6482:
6480:
6478:
6466:
6460:
6459:
6433:
6413:
6407:
6406:
6404:
6402:
6386:
6380:
6379:
6377:
6375:
6369:
6364:. Archived from
6353:
6347:
6345:
6335:
6317:
6308:(2): 1856â1865.
6291:
6285:
6284:
6282:
6280:
6263:
6257:
6256:
6246:
6236:
6218:
6192:
6186:
6185:
6173:
6167:
6166:
6132:
6112:
6106:
6105:
6095:
6079:
6073:
6072:
6070:
6068:
6053:
6047:
6046:
6020:
5995:
5989:
5988:
5980:
5974:
5973:
5971:
5969:
5960:. Archived from
5954:
5948:
5947:
5935:
5929:
5928:
5926:
5924:
5907:
5898:
5897:
5885:
5879:
5878:
5867:
5861:
5860:
5832:
5826:
5825:
5814:
5808:
5807:
5805:
5803:
5791:
5778:
5777:
5775:
5773:
5739:
5723:Nature Astronomy
5713:
5707:
5706:
5704:
5702:
5680:
5674:
5673:
5671:
5669:
5647:
5641:
5640:
5614:
5596:
5587:
5581:
5580:
5578:
5576:
5564:
5558:
5557:
5511:
5505:
5504:
5502:
5500:
5483:
5477:
5476:
5474:
5472:
5457:
5448:
5447:
5445:
5443:
5434:. Archived from
5423:
5417:
5416:
5406:
5396:
5364:
5358:
5357:
5355:
5353:
5338:
5332:
5331:
5329:
5327:
5310:
5304:
5303:
5301:
5299:
5284:
5278:
5277:
5270:
5264:
5263:
5251:
5245:
5244:
5242:
5240:
5225:
5219:
5218:
5182:
5176:
5175:
5142:(4260): 99â105.
5130:
5124:
5123:
5103:
5094:
5093:
5091:
5089:
5072:
5066:
5065:
5063:
5061:
5044:
5038:
5037:
4992:
4983:
4982:
4980:
4978:
4973:on 16 April 2011
4969:. Archived from
4967:Associated Press
4958:
4947:
4946:
4944:
4942:
4923:
4917:
4916:
4914:
4912:
4897:
4891:
4890:
4888:
4886:
4869:
4863:
4862:
4860:
4858:
4847:
4841:
4840:
4806:
4797:
4791:
4790:Bennett, pp. 3-4
4788:
4782:
4781:
4749:
4743:
4742:
4732:
4714:
4690:
4684:
4683:
4681:
4649:
4640:
4639:
4629:
4605:
4599:
4598:
4579:10.1039/b517766a
4558:
4552:
4551:
4518:
4512:
4511:
4509:
4507:
4493:
4487:
4486:
4458:
4452:
4451:
4440:
4434:
4431:
4422:
4419:
4413:
4410:
4404:
4401:
4395:
4392:
4386:
4383:
4377:
4376:
4346:
4340:
4339:
4329:
4319:
4287:
4281:
4280:
4254:
4245:(2): 1050â1070.
4234:
4228:
4225:
4219:
4216:
4210:
4207:
4201:
4200:
4182:
4167:Nature Astronomy
4162:
4156:
4155:
4153:
4151:
4145:
4140:. Archived from
4124:
4118:
4117:
4115:
4113:
4094:
4088:
4087:
4061:
4040:
4034:
4033:
4028:. Archived from
4003:
4001:astro-ph/0505003
3979:
3973:
3972:
3970:
3968:
3954:
3948:
3947:
3920:
3914:
3913:
3877:
3871:
3870:
3868:
3866:
3845:
3839:
3838:
3836:
3834:
3823:
3817:
3816:
3814:
3812:
3800:
3794:
3791:
3785:
3784:
3764:
3758:
3757:
3741:
3731:
3725:
3724:
3704:
3698:
3695:
3689:
3686:
3680:
3679:
3677:
3675:
3663:
3657:
3656:
3654:
3652:
3640:
3621:
3620:
3600:
3594:
3593:
3583:
3572:
3566:
3565:
3563:
3561:
3547:Moskowitz, Clara
3543:
3537:
3536:
3534:
3532:
3520:
3514:
3511:
3505:
3504:
3470:
3450:
3444:
3443:
3431:
3425:
3424:
3422:
3420:
3405:
3399:
3398:
3396:
3394:
3388:
3383:. Archived from
3367:
3358:
3357:
3356:
3354:
3339:
3311:
3305:
3304:
3294:
3246:
3240:
3239:
3229:
3205:
3196:
3195:
3194:
3192:
3151:
3145:
3144:
3136:
3130:
3129:
3121:
3115:
3114:
3106:
3100:
3099:
3091:
3085:
3084:
3082:
3080:
3063:
3057:
3056:
3054:
3052:
3046:
3041:. Archived from
3025:
3019:
3018:
3016:
3014:
3003:
2995:
2979:
2975:
2969:
2966:
2960:
2957:
2951:
2941:
2857:Isaac Ben-Israel
2830:(FAST) program.
2802:define rules of
2682:Parkes Telescope
2655:Native Americans
2550:Lewis White Beck
2481:. Also known as
2418:
2407:
2398:
2356:Svante Arrhenius
2246:William Herschel
2220:planetary system
2163:late Middle Ages
2114:Byzantine Empire
2016:geocentric model
1976:Cosmic pluralism
1970:Cosmic pluralism
1740:nitrogen dioxide
1704:technosignatures
1688:radio telescopes
1642:hydrogen cyanide
1623:ribonucleic acid
1549:in August 2012.
1541:that landed the
1475:) was reported.
1471:) and Mars (via
1370:eruption columns
1253:Milky Way galaxy
1210:Milky Way galaxy
918:Dennis W. Sciama
901:
899:
879:
877:
876:
871:
709:
707:
706:
701:
693:
692:
680:
679:
667:
666:
654:
653:
641:
640:
628:
627:
539:history of Earth
385:
378:
371:
228:
221:
220:
164:Nicholas of Cusa
156:William Vorilong
49:
21:
11954:
11953:
11949:
11948:
11947:
11945:
11944:
11943:
11884:
11883:
11882:
11872:
11870:
11858:
11848:
11846:
11834:
11826:
11824:
11819:
11787:
11724:
11715:Iosif Shklovsky
11663:
11629:Bracewell probe
11624:Arecibo message
11597:
11554:
11549:
11519:
11514:
11504:
11502:
11492:
11490:
11480:
11478:
11458:
11284:
11260:
11251:
11204:
11194:
11137:
11125:
11106:Propionaldehyde
11081:Ethylene glycol
11070:
11062:
11058:
11029:
11027:
11020:
10976:Cyanohexatriyne
10962:
10955:
10902:
10895:
10830:
10823:
10783:
10736:
10729:
10700:Methoxy radical
10630:
10623:
10619:Thiocyanic acid
10500:
10493:
10403:
10343:Ethynyl radical
10279:
10273:
10272:
10271:
10270:
10264:
10263:
10262:
10261:
10252:
10243:Sulfur monoxide
10228:Sodium chloride
10213:Silicon carbide
10120:Diatomic carbon
10110:Carbon monoxide
10052:
10047:
10017:
10012:
9980:
9901:
9891:
9834:
9828:
9789:Icebreaker Life
9727:
9689:
9673:
9647:
9641:
9558:
9464:
9458:
9375:
9368:
9272:
9248:Geomicrobiology
9206:
9201:
9171:
9166:
9162:Xenoarchaeology
9152:Technosignature
9053:
8989:
8975:Kardashev scale
8928:
8890:
8883:
8879:Xenolinguistics
8844:Project Phoenix
8834:Project Cyclops
8819:Lincos language
8782:Bracewell probe
8767:Arecibo message
8748:
8741:
8639:Icebreaker Life
8541:
8453:
8446:
8406:
8401:
8393:
8385:
8377:
8363:
8358:
8350:
8342:
8334:
8320:
8315:
8307:
8286:
8227:
8222:
8180:
8175:
8169:
8146:
8125:
8106:. Random House.
8083:
8082:
8073:
8072:
8059:
8045:Pickover, Cliff
8037:
7997:
7966:
7936:
7913:
7894:
7866:
7847:
7828:
7820:. Ebury Press.
7800:
7781:
7760:
7739:
7737:Further reading
7734:
7717:
7713:
7698:
7694:
7681:
7680:
7673:
7660:
7659:
7655:
7642:
7641:
7637:
7622:
7618:
7603:
7599:
7586:
7585:
7581:
7571:
7569:
7554:
7550:
7540:
7538:
7531:
7524:
7514:
7512:
7503:
7502:
7498:
7488:
7486:
7474:
7470:
7449:
7445:
7435:
7433:
7422:
7418:
7411:
7397:
7393:
7383:
7381:
7380:. 25 April 2010
7372:
7371:
7367:
7360:
7338:
7334:
7324:
7322:
7315:
7311:
7301:
7299:
7290:
7289:
7285:
7275:
7273:
7265:
7264:
7260:
7255:
7251:
7241:
7237:
7206:
7202:
7171:
7167:
7162:
7158:
7148:
7146:
7137:
7136:
7132:
7127:
7123:
7113:
7111:
7104:
7100:
7079:
7075:
7046:(10): 946â950.
7036:
7032:
6998:(92): 261â278.
6986:(August 1871).
6981:
6977:
6957:
6953:
6948:
6944:
6934:
6932:
6924:
6923:
6919:
6912:
6896:
6892:
6871:
6867:
6826:
6822:
6812:
6810:
6803:
6797:
6793:
6783:
6781:
6773:
6772:
6768:
6763:
6759:
6754:
6750:
6745:
6738:
6728:
6726:
6717:
6716:
6712:
6707:
6703:
6698:
6694:
6689:
6685:
6675:
6673:
6671:
6655:
6648:
6643:
6639:
6634:
6630:
6625:
6621:
6611:
6609:
6607:
6591:
6587:
6578:
6574:
6567:
6549:
6545:
6534:Crisis Magazine
6526:
6522:
6515:
6499:
6495:
6490:
6486:
6476:
6474:
6467:
6463:
6414:
6410:
6400:
6398:
6388:
6387:
6383:
6373:
6371:
6354:
6350:
6292:
6288:
6278:
6276:
6264:
6260:
6193:
6189:
6174:
6170:
6113:
6109:
6080:
6076:
6066:
6064:
6063:on 25 July 2015
6055:
6054:
6050:
6003:Mission Data".
5996:
5992:
5981:
5977:
5967:
5965:
5958:"NASA â Kepler"
5956:
5955:
5951:
5936:
5932:
5922:
5920:
5908:
5901:
5886:
5882:
5869:
5868:
5864:
5833:
5829:
5820:. The Columbus
5816:
5815:
5811:
5801:
5799:
5792:
5781:
5771:
5769:
5714:
5710:
5700:
5698:
5681:
5677:
5667:
5665:
5648:
5644:
5594:
5588:
5584:
5574:
5572:
5565:
5561:
5512:
5508:
5498:
5496:
5485:
5484:
5480:
5470:
5468:
5458:
5451:
5441:
5439:
5424:
5420:
5365:
5361:
5351:
5349:
5339:
5335:
5325:
5323:
5311:
5307:
5297:
5295:
5285:
5281:
5272:
5271:
5267:
5252:
5248:
5238:
5236:
5229:"ExoMars rover"
5227:
5226:
5222:
5183:
5179:
5131:
5127:
5120:
5104:
5097:
5087:
5085:
5073:
5069:
5059:
5057:
5045:
5041:
4993:
4986:
4976:
4974:
4959:
4950:
4940:
4938:
4924:
4920:
4910:
4908:
4898:
4894:
4884:
4882:
4870:
4866:
4856:
4854:
4849:
4848:
4844:
4804:
4798:
4794:
4789:
4785:
4750:
4746:
4691:
4687:
4650:
4643:
4606:
4602:
4573:(10): 858â875.
4559:
4555:
4519:
4515:
4505:
4503:
4495:
4494:
4490:
4459:
4455:
4442:
4441:
4437:
4432:
4425:
4420:
4416:
4411:
4407:
4402:
4398:
4393:
4389:
4384:
4380:
4373:
4347:
4343:
4288:
4284:
4235:
4231:
4226:
4222:
4217:
4213:
4208:
4204:
4163:
4159:
4149:
4147:
4128:Overbye, Dennis
4125:
4121:
4111:
4109:
4096:
4095:
4091:
4041:
4037:
3980:
3976:
3966:
3964:
3955:
3951:
3944:
3921:
3917:
3878:
3874:
3864:
3862:
3855:Nova ScienceNow
3846:
3842:
3832:
3830:
3825:
3824:
3820:
3810:
3808:
3801:
3797:
3792:
3788:
3781:
3765:
3761:
3754:
3732:
3728:
3721:
3705:
3701:
3696:
3692:
3687:
3683:
3673:
3671:
3664:
3660:
3650:
3648:
3641:
3624:
3617:
3601:
3597:
3581:
3573:
3569:
3559:
3557:
3544:
3540:
3530:
3528:
3521:
3517:
3512:
3508:
3451:
3447:
3432:
3428:
3418:
3416:
3406:
3402:
3392:
3390:
3371:Overbye, Dennis
3368:
3361:
3352:
3350:
3348:
3312:
3308:
3247:
3243:
3206:
3199:
3190:
3188:
3186:
3152:
3148:
3137:
3133:
3122:
3118:
3107:
3103:
3092:
3088:
3078:
3076:
3064:
3060:
3050:
3048:
3026:
3022:
3012:
3010:
2996:
2992:
2988:
2983:
2982:
2976:
2972:
2967:
2963:
2958:
2954:
2942:
2938:
2933:
2928:
2874:Assembly theory
2869:
2792:
2786:
2774:alien abduction
2758:science fiction
2724:
2718:
2643:Stephen Hawking
2618:Donald Brownlee
2475:
2474:
2473:
2472:
2427:The search for
2421:
2420:
2419:
2410:
2409:
2408:
2400:
2399:
2388:
2382:
2294:Percival Lowell
2278:
2200:Galileo Galilei
2192:Johannes Kepler
2145:
2075:Airavat Kshetra
1978:
1972:
1967:
1957:
1951:
1922:. The study of
1838:false positives
1798:
1792:
1786:
1768:Kardashev scale
1760:Light pollution
1756:ozone depletion
1742:as a result of
1676:
1670:
1660:leading to the
1618:IRAS 16293-2422
1532:Rio Tinto river
1481:
1410:
1404:
1274:Besides Earth,
1268:
1262:
1206:
1176:and heads with
1087:Norman Horowitz
1056:(three bonds),
975:Magnetic fields
963:plate tectonics
946:
940:
934:
897:
895:
885:social sciences
823:
820:
819:
805:
790:
779:
768:
754:
736:
688:
684:
675:
671:
662:
658:
649:
645:
636:
632:
623:
619:
611:
608:
607:
551:Stephen Hawking
527:
519:Main articles:
517:
389:
219:
206:Science fiction
145:The City of God
87:(colloquially,
78:
77:
72:
66:
60:
54:
51:
42:
35:
28:
23:
22:
15:
12:
11:
5:
11952:
11942:
11941:
11936:
11931:
11926:
11921:
11916:
11911:
11906:
11901:
11896:
11881:
11880:
11868:
11856:
11844:
11821:
11820:
11818:
11817:
11805:
11792:
11789:
11788:
11786:
11785:
11780:
11775:
11770:
11765:
11760:
11758:Drake equation
11755:
11750:
11745:
11738:
11736:Alien language
11732:
11730:
11726:
11725:
11723:
11722:
11717:
11712:
11707:
11702:
11697:
11692:
11687:
11682:
11677:
11671:
11669:
11665:
11664:
11662:
11661:
11656:
11651:
11649:Pioneer plaque
11646:
11641:
11636:
11631:
11626:
11621:
11616:
11611:
11605:
11603:
11599:
11598:
11596:
11595:
11590:
11585:
11584:
11583:
11578:
11568:
11562:
11560:
11556:
11555:
11548:
11547:
11540:
11533:
11525:
11516:
11515:
11513:
11512:
11500:
11488:
11476:
11463:
11460:
11459:
11457:
11456:
11451:
11446:
11441:
11435:
11430:
11425:
11420:
11415:
11410:
11405:
11400:
11395:
11390:
11385:
11380:
11375:
11370:
11365:
11360:
11355:
11350:
11345:
11343:Cosmochemistry
11340:
11335:
11330:
11325:
11320:
11315:
11310:
11308:Astrochemistry
11305:
11300:
11294:
11292:
11286:
11285:
11283:
11282:
11277:
11272:
11267:
11262:
11258:
11254:
11249:
11245:
11240:
11235:
11230:
11225:
11220:
11214:
11212:
11206:
11205:
11203:
11202:
11197:
11192:
11188:
11183:
11178:
11173:
11168:
11163:
11161:Formyl radical
11158:
11153:
11147:
11141:
11139:
11131:
11130:
11127:
11126:
11124:
11123:
11118:
11113:
11108:
11103:
11098:
11093:
11091:Methyl acetate
11088:
11083:
11078:
11073:
11068:
11064:
11060:
11056:
11050:
11045:
11040:
11034:
11032:
11022:
11021:
11019:
11018:
11013:
11008:
11003:
10998:
10993:
10988:
10983:
10981:Dimethyl ether
10978:
10973:
10967:
10965:
10957:
10956:
10954:
10953:
10948:
10946:Methyl formate
10943:
10938:
10933:
10931:Glycolaldehyde
10928:
10923:
10918:
10913:
10907:
10905:
10897:
10896:
10894:
10893:
10888:
10883:
10878:
10873:
10868:
10866:Glycolonitrile
10863:
10861:Ethylene oxide
10858:
10853:
10852:
10851:
10841:
10835:
10833:
10825:
10824:
10822:
10821:
10816:
10811:
10806:
10801:
10796:
10791:
10786:
10781:
10777:
10772:
10767:
10762:
10760:Cyclopropenone
10757:
10752:
10747:
10741:
10739:
10731:
10730:
10728:
10727:
10722:
10717:
10712:
10707:
10702:
10697:
10692:
10687:
10682:
10677:
10672:
10667:
10662:
10660:Cyanoacetylene
10657:
10652:
10647:
10642:
10635:
10633:
10625:
10624:
10622:
10621:
10616:
10611:
10606:
10601:
10596:
10591:
10586:
10581:
10579:Methyl radical
10576:
10571:
10566:
10561:
10556:
10554:Isocyanic acid
10551:
10546:
10541:
10536:
10531:
10526:
10521:
10519:Isocyanic acid
10516:
10511:
10505:
10503:
10495:
10494:
10492:
10491:
10486:
10481:
10476:
10471:
10466:
10464:Sulfur dioxide
10461:
10456:
10451:
10446:
10441:
10439:Sodium cyanide
10436:
10431:
10426:
10421:
10416:
10411:
10406:
10401:
10397:
10392:
10387:
10382:
10377:
10372:
10367:
10362:
10356:
10350:
10348:Formyl radical
10345:
10340:
10335:
10330:
10325:
10320:
10315:
10310:
10308:Carbon dioxide
10305:
10300:
10295:
10289:
10287:
10281:
10280:
10255:
10253:
10251:
10250:
10245:
10240:
10235:
10230:
10225:
10220:
10215:
10210:
10205:
10200:
10195:
10189:
10184:
10179:
10173:
10168:
10163:
10158:
10156:Iron(II) oxide
10153:
10148:
10142:
10137:
10132:
10127:
10122:
10117:
10112:
10107:
10102:
10097:
10092:
10087:
10082:
10077:
10071:
10069:
10060:
10054:
10053:
10046:
10045:
10038:
10031:
10023:
10014:
10013:
10011:
10010:
9998:
9985:
9982:
9981:
9979:
9978:
9973:
9968:
9963:
9958:
9953:
9948:
9943:
9938:
9937:
9936:
9931:
9926:
9916:
9911:
9905:
9903:
9897:
9896:
9893:
9892:
9890:
9889:
9884:
9879:
9877:Northern Light
9874:
9869:
9864:
9859:
9854:
9849:
9844:
9838:
9836:
9833:Cancelled and
9830:
9829:
9827:
9826:
9821:
9816:
9811:
9806:
9801:
9796:
9791:
9786:
9781:
9776:
9771:
9766:
9761:
9756:
9751:
9746:
9741:
9735:
9733:
9729:
9728:
9726:
9725:
9724:
9723:
9710:
9708:Europa Clipper
9705:
9697:
9695:
9691:
9690:
9688:
9687:
9681:
9679:
9675:
9674:
9672:
9671:
9664:
9659:
9651:
9649:
9643:
9642:
9640:
9639:
9634:
9629:
9628:
9627:
9614:
9607:
9606:
9605:
9592:
9591:
9590:
9577:
9572:
9566:
9564:
9560:
9559:
9557:
9556:
9551:
9546:
9541:
9536:
9531:
9526:
9521:
9516:
9511:
9506:
9501:
9496:
9491:
9486:
9481:
9475:
9473:
9466:
9460:
9459:
9457:
9456:
9451:
9446:
9441:
9436:
9431:
9426:
9421:
9416:
9411:
9406:
9401:
9396:
9391:
9386:
9380:
9378:
9370:
9369:
9367:
9366:
9361:
9356:
9351:
9346:
9341:
9336:
9331:
9326:
9321:
9316:
9311:
9306:
9304:Drake equation
9301:
9296:
9291:
9286:
9280:
9278:
9274:
9273:
9271:
9270:
9265:
9260:
9255:
9250:
9245:
9243:Exoplanetology
9240:
9235:
9230:
9225:
9220:
9218:Astrochemistry
9214:
9212:
9208:
9207:
9200:
9199:
9192:
9185:
9177:
9168:
9167:
9165:
9164:
9159:
9154:
9149:
9144:
9139:
9134:
9129:
9124:
9119:
9114:
9109:
9104:
9099:
9094:
9089:
9084:
9079:
9074:
9069:
9063:
9061:
9059:Related topics
9055:
9054:
9052:
9051:
9049:Zoo hypothesis
9046:
9041:
9036:
9031:
9026:
9021:
9016:
9011:
9006:
9000:
8998:
8991:
8990:
8988:
8987:
8982:
8977:
8972:
8967:
8962:
8957:
8952:
8950:Drake equation
8947:
8942:
8936:
8934:
8930:
8929:
8927:
8926:
8921:
8916:
8911:
8906:
8901:
8895:
8893:
8885:
8884:
8882:
8881:
8876:
8871:
8866:
8861:
8856:
8851:
8846:
8841:
8836:
8831:
8829:Pioneer plaque
8826:
8821:
8816:
8811:
8806:
8801:
8800:
8799:
8794:
8784:
8779:
8774:
8769:
8764:
8759:
8753:
8751:
8743:
8742:
8740:
8739:
8732:
8725:
8720:
8715:
8710:
8702:
8697:
8689:
8681:
8679:Northern Light
8676:
8671:
8666:
8661:
8656:
8651:
8646:
8641:
8636:
8631:
8626:
8621:
8620:
8619:
8606:
8603:Europa Clipper
8599:
8594:
8589:
8582:
8575:
8567:
8562:
8557:
8551:
8549:
8547:Space missions
8543:
8542:
8540:
8539:
8534:
8529:
8524:
8519:
8514:
8509:
8504:
8499:
8494:
8489:
8484:
8479:
8474:
8469:
8464:
8458:
8456:
8448:
8447:
8445:
8444:
8439:
8434:
8429:
8424:
8418:
8416:
8412:
8411:
8408:
8407:
8405:
8404:
8402:(radio signal)
8396:
8388:
8386:(inconclusive)
8380:
8378:(radio source)
8371:
8369:
8365:
8364:
8362:
8361:
8353:
8345:
8340:EPIC 204278916
8337:
8328:
8326:
8322:
8321:
8319:
8318:
8310:
8301:
8299:
8292:
8288:
8287:
8285:
8284:
8278:
8272:
8266:
8260:
8254:
8248:
8242:
8235:
8233:
8229:
8228:
8221:
8220:
8213:
8206:
8198:
8192:
8191:
8186:
8179:
8178:External links
8176:
8174:
8173:
8167:
8150:
8144:
8129:
8123:
8108:
8092:
8063:
8057:
8041:
8035:
8018:
8001:
7995:
7982:
7970:
7964:
7949:
7940:
7934:
7917:
7911:
7898:
7892:
7879:
7870:
7864:
7851:
7845:
7832:
7826:
7804:
7798:
7785:
7779:
7764:
7758:
7740:
7738:
7735:
7733:
7732:
7711:
7692:
7671:
7653:
7635:
7616:
7597:
7579:
7548:
7522:
7496:
7468:
7443:
7416:
7409:
7391:
7365:
7358:
7344:. Copernicus.
7332:
7309:
7283:
7258:
7249:
7235:
7200:
7165:
7156:
7145:on 26 May 2018
7130:
7121:
7098:
7073:
7030:
6975:
6951:
6942:
6917:
6910:
6890:
6865:
6844:(8): 488â499.
6830:Maunder, E. W.
6828:Evans, J. E.;
6820:
6791:
6766:
6757:
6748:
6736:
6710:
6708:Bennett, p. 29
6701:
6692:
6683:
6669:
6646:
6644:Bennett, p. 31
6637:
6635:Bennett, p. 24
6628:
6619:
6605:
6585:
6572:
6565:
6543:
6520:
6513:
6493:
6484:
6461:
6408:
6381:
6348:
6286:
6258:
6187:
6168:
6107:
6074:
6048:
5990:
5975:
5949:
5930:
5899:
5880:
5862:
5843:(1): 149â156.
5827:
5809:
5779:
5730:(2): 164â173.
5708:
5675:
5642:
5582:
5559:
5524:(7371): 80â3.
5506:
5478:
5449:
5438:on 11 May 2020
5418:
5359:
5333:
5305:
5279:
5265:
5246:
5220:
5193:(4): 545â577.
5177:
5125:
5118:
5095:
5067:
5039:
4984:
4948:
4918:
4892:
4864:
4842:
4792:
4783:
4764:(2): 105â112.
4744:
4685:
4641:
4620:(3): 202â216.
4600:
4553:
4534:(3): 370â381.
4513:
4488:
4469:(3): 204â208.
4453:
4435:
4423:
4414:
4405:
4396:
4387:
4378:
4371:
4363:10.17226/11919
4341:
4302:(3): 805â808.
4282:
4229:
4220:
4211:
4202:
4157:
4119:
4089:
4035:
3974:
3949:
3942:
3915:
3888:(3): 243â250.
3872:
3840:
3818:
3795:
3786:
3779:
3759:
3752:
3726:
3719:
3699:
3690:
3681:
3658:
3622:
3615:
3595:
3567:
3538:
3515:
3506:
3445:
3426:
3400:
3359:
3346:
3320:Volcanic Lakes
3306:
3261:(4): 429â452.
3241:
3197:
3184:
3146:
3131:
3116:
3101:
3086:
3058:
3020:
2989:
2987:
2984:
2981:
2980:
2970:
2961:
2952:
2935:
2934:
2932:
2929:
2927:
2926:
2921:
2916:
2914:Sentiocentrism
2911:
2906:
2901:
2896:
2891:
2886:
2881:
2876:
2870:
2868:
2865:
2835:Dmitry Rogozin
2800:Moon Agreement
2785:
2782:
2750:Charles Darwin
2720:Main article:
2717:
2714:
2686:Geoffrey Marcy
2675:Robert C. Byrd
2667:SETI Institute
2615:astrobiologist
2608:paleontologist
2579:Charles Darwin
2575:Thomas Wilkins
2515:pseudosciences
2471:
2470:
2449:
2439:
2423:
2422:
2413:
2412:
2411:
2402:
2401:
2393:
2392:
2391:
2390:
2389:
2381:
2380:Recent history
2378:
2290:Martian canals
2277:
2274:
2216:Giordano Bruno
2204:paradigm shift
2144:
2141:
2067:Bharat Kshetra
2002:Ancient Greece
1974:Main article:
1971:
1968:
1953:Main article:
1950:
1947:
1898:listed on the
1888:PSR B1257+12 A
1863:, located 4.2
1845:Sun-like stars
1788:Main article:
1785:
1782:
1719:SETI Institute
1686:is one of the
1672:Main article:
1669:
1666:
1662:origin of life
1609:glycolaldehyde
1480:
1477:
1467:on Venus (via
1461:microorganisms
1406:Main article:
1403:
1400:
1264:Main article:
1261:
1258:
1244:chemosynthetic
1231:solar system.
1228:Earth's mantle
1205:
1202:
1178:sensory organs
936:Main article:
933:
930:
869:
866:
863:
860:
857:
854:
851:
848:
845:
842:
839:
836:
833:
830:
827:
814:
813:
807:
801:
796:
786:
781:
775:
770:
764:
759:
750:
745:
739:star formation
734:
725:
724:
711:
710:
699:
696:
691:
687:
683:
678:
674:
670:
665:
661:
657:
652:
648:
644:
639:
635:
631:
626:
622:
618:
615:
586:Drake equation
521:Drake equation
516:
513:
498:solar activity
397:microorganisms
391:
390:
388:
387:
380:
373:
365:
362:
361:
360:
359:
354:
349:
344:
339:
334:
329:
321:
320:
316:
315:
314:
313:
308:
300:
299:
292:
291:
290:
289:
284:
279:
274:
269:
264:
256:
255:
249:
248:
242:
241:
235:
234:
230:
229:
218:
215:
188:volcanic lakes
117:Drake equation
111:that might be
73:
52:
46:
26:
9:
6:
4:
3:
2:
11951:
11940:
11937:
11935:
11932:
11930:
11927:
11925:
11922:
11920:
11917:
11915:
11912:
11910:
11907:
11905:
11902:
11900:
11897:
11895:
11892:
11891:
11889:
11879:
11869:
11867:
11862:
11857:
11855:
11845:
11843:
11838:
11833:
11832:
11829:
11816:
11815:
11811:
11806:
11804:
11803:
11794:
11793:
11790:
11784:
11781:
11779:
11776:
11774:
11773:Fermi paradox
11771:
11769:
11766:
11764:
11761:
11759:
11756:
11754:
11751:
11749:
11746:
11744:
11743:
11739:
11737:
11734:
11733:
11731:
11727:
11721:
11718:
11716:
11713:
11711:
11708:
11706:
11703:
11701:
11698:
11696:
11693:
11691:
11688:
11686:
11683:
11681:
11678:
11676:
11673:
11672:
11670:
11666:
11660:
11657:
11655:
11652:
11650:
11647:
11645:
11642:
11640:
11637:
11635:
11632:
11630:
11627:
11625:
11622:
11620:
11617:
11615:
11612:
11610:
11607:
11606:
11604:
11600:
11594:
11591:
11589:
11586:
11582:
11579:
11577:
11574:
11573:
11572:
11569:
11567:
11564:
11563:
11561:
11557:
11553:
11546:
11541:
11539:
11534:
11532:
11527:
11526:
11523:
11511:
11501:
11499:
11489:
11487:
11477:
11475:
11474:
11465:
11464:
11461:
11455:
11452:
11450:
11447:
11445:
11442:
11439:
11436:
11434:
11431:
11429:
11426:
11424:
11421:
11419:
11416:
11414:
11411:
11409:
11406:
11404:
11401:
11399:
11396:
11394:
11391:
11389:
11386:
11384:
11381:
11379:
11376:
11374:
11373:Homochirality
11371:
11369:
11366:
11364:
11361:
11359:
11356:
11354:
11351:
11349:
11346:
11344:
11341:
11339:
11336:
11334:
11331:
11329:
11326:
11324:
11321:
11319:
11316:
11314:
11311:
11309:
11306:
11304:
11301:
11299:
11296:
11295:
11293:
11291:
11287:
11281:
11278:
11276:
11273:
11271:
11268:
11266:
11263:
11261:
11255:
11253:
11246:
11244:
11241:
11239:
11236:
11234:
11231:
11229:
11228:Methoxyethane
11226:
11224:
11221:
11219:
11216:
11215:
11213:
11211:
11207:
11201:
11198:
11196:
11189:
11187:
11184:
11182:
11179:
11177:
11174:
11172:
11169:
11167:
11164:
11162:
11159:
11157:
11154:
11151:
11148:
11146:
11143:
11142:
11140:
11136:
11132:
11122:
11119:
11117:
11114:
11112:
11111:Butyronitrile
11109:
11107:
11104:
11102:
11099:
11097:
11094:
11092:
11089:
11087:
11086:Ethyl formate
11084:
11082:
11079:
11077:
11074:
11072:
11065:
11054:
11051:
11049:
11046:
11044:
11041:
11039:
11036:
11035:
11033:
11031:
11023:
11017:
11014:
11012:
11011:Propionitrile
11009:
11007:
11004:
11002:
10999:
10997:
10994:
10992:
10989:
10987:
10984:
10982:
10979:
10977:
10974:
10972:
10969:
10968:
10966:
10964:
10958:
10952:
10949:
10947:
10944:
10942:
10939:
10937:
10934:
10932:
10929:
10927:
10924:
10922:
10919:
10917:
10914:
10912:
10909:
10908:
10906:
10904:
10898:
10892:
10891:Vinyl alcohol
10889:
10887:
10884:
10882:
10879:
10877:
10874:
10872:
10869:
10867:
10864:
10862:
10859:
10857:
10854:
10850:
10849:Vinyl cyanide
10847:
10846:
10845:
10844:Acrylonitrile
10842:
10840:
10837:
10836:
10834:
10832:
10826:
10820:
10817:
10815:
10812:
10810:
10809:Pentynylidyne
10807:
10805:
10802:
10800:
10797:
10795:
10792:
10790:
10787:
10785:
10778:
10776:
10773:
10771:
10768:
10766:
10763:
10761:
10758:
10756:
10753:
10751:
10748:
10746:
10743:
10742:
10740:
10738:
10732:
10726:
10723:
10721:
10718:
10716:
10713:
10711:
10708:
10706:
10705:Methylenimine
10703:
10701:
10698:
10696:
10693:
10691:
10688:
10686:
10683:
10681:
10678:
10676:
10673:
10671:
10668:
10666:
10663:
10661:
10658:
10656:
10653:
10651:
10648:
10646:
10643:
10640:
10637:
10636:
10634:
10632:
10626:
10620:
10617:
10615:
10612:
10610:
10607:
10605:
10602:
10600:
10597:
10595:
10592:
10590:
10587:
10585:
10584:Propynylidyne
10582:
10580:
10577:
10575:
10574:Methyl cation
10572:
10570:
10567:
10565:
10562:
10560:
10557:
10555:
10552:
10550:
10547:
10545:
10542:
10540:
10537:
10535:
10534:Fulminic acid
10532:
10530:
10527:
10525:
10522:
10520:
10517:
10515:
10512:
10510:
10507:
10506:
10504:
10502:
10496:
10490:
10487:
10485:
10482:
10480:
10477:
10475:
10472:
10470:
10467:
10465:
10462:
10460:
10457:
10455:
10452:
10450:
10447:
10445:
10442:
10440:
10437:
10435:
10432:
10430:
10427:
10425:
10422:
10420:
10417:
10415:
10412:
10410:
10409:Nitrous oxide
10407:
10405:
10398:
10396:
10393:
10391:
10388:
10386:
10383:
10381:
10378:
10376:
10373:
10371:
10368:
10366:
10363:
10360:
10357:
10354:
10351:
10349:
10346:
10344:
10341:
10339:
10336:
10334:
10331:
10329:
10326:
10324:
10321:
10319:
10316:
10314:
10311:
10309:
10306:
10304:
10303:Amino radical
10301:
10299:
10296:
10294:
10291:
10290:
10288:
10286:
10282:
10277:
10268:
10259:
10249:
10246:
10244:
10241:
10239:
10236:
10234:
10233:Sodium iodide
10231:
10229:
10226:
10224:
10221:
10219:
10216:
10214:
10211:
10209:
10206:
10204:
10201:
10199:
10196:
10193:
10190:
10188:
10185:
10183:
10180:
10177:
10174:
10172:
10169:
10167:
10164:
10162:
10159:
10157:
10154:
10152:
10149:
10146:
10143:
10141:
10138:
10136:
10133:
10131:
10128:
10126:
10123:
10121:
10118:
10116:
10115:Cyano radical
10113:
10111:
10108:
10106:
10103:
10101:
10098:
10096:
10095:Carbon cation
10093:
10091:
10088:
10086:
10083:
10081:
10078:
10076:
10073:
10072:
10070:
10068:
10064:
10061:
10059:
10055:
10051:
10044:
10039:
10037:
10032:
10030:
10025:
10024:
10021:
10009:
10008:
9999:
9997:
9996:
9987:
9986:
9983:
9977:
9974:
9972:
9969:
9967:
9964:
9962:
9959:
9957:
9954:
9952:
9949:
9947:
9944:
9942:
9939:
9935:
9932:
9930:
9927:
9925:
9922:
9921:
9920:
9917:
9915:
9912:
9910:
9907:
9906:
9904:
9898:
9888:
9885:
9883:
9880:
9878:
9875:
9873:
9870:
9868:
9865:
9863:
9860:
9858:
9855:
9853:
9850:
9848:
9845:
9843:
9840:
9839:
9837:
9831:
9825:
9822:
9820:
9817:
9815:
9812:
9810:
9807:
9805:
9802:
9800:
9797:
9795:
9792:
9790:
9787:
9785:
9782:
9780:
9777:
9775:
9774:Europa Lander
9772:
9770:
9767:
9765:
9762:
9760:
9757:
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9680:
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9357:
9355:
9352:
9350:
9347:
9345:
9342:
9340:
9337:
9335:
9332:
9330:
9329:Extremophiles
9327:
9325:
9322:
9320:
9317:
9315:
9312:
9310:
9307:
9305:
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9300:
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9056:
9050:
9047:
9045:
9042:
9040:
9037:
9035:
9032:
9030:
9027:
9025:
9022:
9020:
9017:
9015:
9012:
9010:
9007:
9005:
9002:
9001:
8999:
8996:
8995:Fermi paradox
8992:
8986:
8983:
8981:
8978:
8976:
8973:
8971:
8968:
8966:
8963:
8961:
8960:Fermi paradox
8958:
8956:
8953:
8951:
8948:
8946:
8943:
8941:
8938:
8937:
8935:
8931:
8925:
8922:
8920:
8919:Nordic aliens
8917:
8915:
8912:
8910:
8907:
8905:
8902:
8900:
8899:Energy beings
8897:
8896:
8894:
8892:
8886:
8880:
8877:
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8810:
8807:
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8798:
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8744:
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8709:
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8688:
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8672:
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8657:
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8637:
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8515:
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8500:
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8490:
8488:
8485:
8483:
8480:
8478:
8475:
8473:
8470:
8468:
8465:
8463:
8460:
8459:
8457:
8455:
8449:
8443:
8442:Life on Titan
8440:
8438:
8435:
8433:
8432:Life on Venus
8430:
8428:
8425:
8423:
8420:
8419:
8417:
8413:
8400:
8397:
8392:
8389:
8384:
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8376:
8373:
8372:
8370:
8366:
8357:
8354:
8349:
8346:
8341:
8338:
8333:
8330:
8329:
8327:
8323:
8314:
8311:
8306:
8303:
8302:
8300:
8298:Misidentified
8296:
8293:
8289:
8282:
8279:
8276:
8275:Yamato 000593
8273:
8270:
8267:
8264:
8261:
8258:
8255:
8252:
8249:
8246:
8243:
8240:
8237:
8236:
8234:
8230:
8226:
8219:
8214:
8212:
8207:
8205:
8200:
8199:
8196:
8190:
8187:
8185:
8182:
8181:
8170:
8164:
8159:
8158:
8151:
8147:
8141:
8137:
8136:
8130:
8126:
8120:
8117:. MIT Press.
8116:
8115:
8109:
8105:
8101:
8097:
8093:
8089:
8077:
8069:
8064:
8060:
8054:
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8019:
8015:
8011:
8007:
8002:
7998:
7992:
7988:
7983:
7980:
7979:
7974:
7973:Gribbin, John
7971:
7967:
7961:
7957:
7956:
7950:
7946:
7941:
7937:
7931:
7926:
7925:
7918:
7914:
7908:
7905:. Cambridge.
7904:
7899:
7895:
7889:
7886:. Cambridge.
7885:
7880:
7876:
7871:
7867:
7861:
7857:
7852:
7848:
7842:
7839:. Cambridge.
7838:
7833:
7829:
7823:
7819:
7818:
7813:
7809:
7805:
7801:
7795:
7791:
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7765:
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7755:
7751:
7747:
7742:
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7728:
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7722:
7715:
7707:
7703:
7696:
7688:
7687:New Scientist
7684:
7678:
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7657:
7649:
7645:
7639:
7631:
7627:
7620:
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7567:
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7559:
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7536:
7529:
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7506:
7500:
7485:
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7472:
7464:
7460:
7459:
7454:
7447:
7431:
7427:
7420:
7412:
7406:
7402:
7395:
7379:
7375:
7369:
7361:
7355:
7351:
7347:
7343:
7336:
7320:
7313:
7297:
7293:
7287:
7272:
7268:
7262:
7256:Bennett, p. 4
7253:
7247:
7245:
7239:
7231:
7227:
7223:
7219:
7216:(1â2): 2â15.
7215:
7211:
7204:
7196:
7192:
7188:
7184:
7180:
7176:
7169:
7160:
7144:
7140:
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7109:
7102:
7094:
7090:
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7027:
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6993:
6989:
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6979:
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6927:
6921:
6913:
6907:
6903:
6902:
6894:
6886:
6882:
6878:
6877:
6869:
6860:
6855:
6851:
6847:
6843:
6839:
6835:
6832:(June 1903).
6831:
6824:
6809:
6802:
6795:
6780:
6776:
6770:
6761:
6755:Bennet, p. 30
6752:
6743:
6741:
6724:
6720:
6714:
6705:
6696:
6687:
6672:
6670:9780520233911
6666:
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6632:
6623:
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6497:
6488:
6472:
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5866:
5858:
5854:
5850:
5846:
5842:
5838:
5831:
5823:
5819:
5813:
5797:
5794:Pat Brennan.
5790:
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5759:
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5751:
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4015:
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3997:
3993:
3989:
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3978:
3963:
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3891:
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3876:
3861:
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3806:
3799:
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3776:
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3763:
3755:
3749:
3745:
3740:
3739:
3730:
3722:
3716:
3712:
3711:
3703:
3697:Bennet, p. 51
3694:
3685:
3669:
3662:
3646:
3639:
3637:
3635:
3633:
3631:
3629:
3627:
3618:
3612:
3608:
3607:
3599:
3591:
3587:
3580:
3579:
3571:
3556:
3552:
3548:
3542:
3526:
3519:
3513:Bennett, p. 3
3510:
3502:
3498:
3494:
3490:
3486:
3482:
3478:
3474:
3469:
3464:
3460:
3456:
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3411:
3404:
3387:
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3366:
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3333:
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3321:
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3256:
3252:
3245:
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3211:
3204:
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3150:
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3112:
3105:
3097:
3090:
3075:
3074:
3073:New Scientist
3069:
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3002:
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2907:
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2900:
2897:
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2887:
2885:
2882:
2880:
2877:
2875:
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2864:
2862:
2858:
2855:
2850:
2847:
2842:
2840:
2836:
2831:
2829:
2825:
2824:space program
2820:
2816:
2813:
2809:
2805:
2801:
2798:and the 1979
2797:
2791:
2781:
2779:
2775:
2771:
2766:
2764:
2759:
2755:
2751:
2747:
2746:
2741:
2732:
2728:
2723:
2713:
2711:
2707:
2703:
2699:
2695:
2691:
2687:
2683:
2679:
2676:
2672:
2668:
2664:
2660:
2659:Jared Diamond
2656:
2652:
2648:
2644:
2639:
2637:
2633:
2629:
2625:
2624:
2619:
2616:
2612:
2609:
2603:
2601:
2597:
2591:
2587:
2584:
2580:
2576:
2572:
2571:Immanuel Kant
2568:
2564:
2560:
2556:
2551:
2546:
2544:
2540:
2536:
2532:
2531:UFO sightings
2528:
2524:
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2369:
2364:
2359:
2357:
2353:
2349:
2345:
2341:
2336:
2332:
2328:
2327:Louis Pasteur
2324:
2319:
2317:
2313:
2309:
2308:Spectroscopic
2305:
2303:
2299:
2295:
2291:
2282:
2273:
2271:
2267:
2266:Enlightenment
2263:
2259:
2258:Immanuel Kant
2255:
2251:
2247:
2242:
2238:
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2232:
2227:
2225:
2221:
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2197:
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2176:
2172:
2168:
2164:
2157:
2153:
2149:
2140:
2138:
2134:
2129:
2127:
2123:
2122:creator deity
2119:
2115:
2110:
2105:
2102:
2101:
2096:
2092:
2088:
2084:
2080:
2076:
2072:
2068:
2064:
2058:
2055:
2051:
2050:
2045:
2044:
2043:Aristotelians
2039:
2035:
2034:
2028:
2026:
2022:
2017:
2012:
2008:
2003:
1999:
1995:
1987:
1982:
1977:
1966:
1962:
1956:
1946:
1944:
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1936:
1935:spectrography
1932:
1927:
1925:
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1917:
1913:
1909:
1905:
1901:
1897:
1893:
1889:
1885:
1880:
1878:
1874:
1873:constellation
1870:
1866:
1862:
1857:
1855:
1854:rogue planets
1851:
1846:
1841:
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1827:
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1802:
1797:
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1774:
1769:
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1753:
1749:
1745:
1744:air pollution
1741:
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1733:
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1715:
1713:
1712:Dyson spheres
1709:
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1529:
1524:
1521:
1516:
1514:
1510:
1506:
1502:
1498:
1494:
1493:biosignatures
1485:
1476:
1474:
1470:
1466:
1462:
1458:
1454:
1450:
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1435:
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1399:
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1383:
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1376:
1371:
1367:
1363:
1358:
1354:
1350:
1345:
1343:
1339:
1334:
1331:
1327:
1326:water on Mars
1323:
1319:
1317:
1316:life on Venus
1313:
1309:
1305:
1300:
1298:
1294:
1285:
1281:
1277:
1272:
1267:
1257:
1254:
1250:
1245:
1241:
1237:
1232:
1229:
1225:
1220:
1215:
1211:
1201:
1199:
1195:
1191:
1187:
1183:
1179:
1175:
1171:
1167:
1163:
1159:
1154:
1149:
1147:
1143:
1139:
1135:
1131:
1130:cell membrane
1127:
1123:
1119:
1115:
1111:
1107:
1103:
1098:
1096:
1092:
1088:
1084:
1079:
1075:
1074:Earth's crust
1071:
1067:
1063:
1059:
1055:
1051:
1047:
1043:
1039:
1035:
1031:
1027:
1023:
1018:
1016:
1012:
1008:
1004:
1000:
996:
991:
987:
982:
980:
979:radioactivity
976:
972:
971:black smokers
968:
964:
960:
955:
951:
945:
939:
929:
927:
923:
919:
915:
914:Fermi paradox
910:
908:
907:
893:
888:
886:
880:
867:
864:
861:
858:
855:
852:
849:
846:
843:
840:
837:
834:
831:
828:
825:
817:
811:
808:
804:
800:
797:
794:
789:
785:
782:
778:
774:
771:
767:
763:
760:
758:
753:
749:
746:
744:
740:
733:
730:
729:
728:
723:
719:
716:
715:
714:
697:
694:
689:
685:
681:
676:
672:
668:
663:
659:
655:
650:
646:
642:
637:
633:
629:
624:
620:
616:
613:
606:
605:
604:
602:
599:
595:
591:
587:
583:
578:
575:
571:
566:
564:
560:
556:
552:
548:
544:
543:physical laws
540:
536:
532:
526:
522:
512:
510:
505:
503:
499:
495:
491:
486:
481:
476:
474:
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457:
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445:
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429:
425:
421:
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398:
386:
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367:
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328:
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324:
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318:
317:
312:
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302:
301:
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294:
293:
288:
285:
283:
280:
278:
275:
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265:
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259:
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214:
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207:
203:
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185:
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165:
161:
157:
153:
149:
147:
146:
141:
137:
133:
129:
124:
122:
118:
114:
110:
109:civilizations
106:
102:
98:
94:
90:
86:
82:
76:
70:
64:
58:
55:What are the
44:
40:
33:
19:
11894:Astrobiology
11814:Space Portal
11807:
11795:
11762:
11748:Astrobiology
11740:
11466:
11449:Spectroscopy
11357:
11303:Astrobiology
11156:Formaldehyde
11048:Benzonitrile
10839:Acetaldehyde
10794:Methanethiol
10745:Acetonitrile
10650:Carbodiimide
10529:Formaldehyde
10524:Cyanoethynyl
10375:Iron cyanide
10370:Hydroperoxyl
10171:Nitric oxide
10005:
9993:
9902:and programs
9900:Institutions
9718:
9700:
9678:Heliocentric
9666:
9654:
9622:
9609:
9601:Perseverance
9600:
9585:
9389:Earth analog
9376:habitability
9344:Ocean planet
9318:
9314:Earth analog
9299:Biosignature
9258:Paleontology
9253:Microbiology
9233:Biochemistry
9223:Astrophysics
9204:Astrobiology
9157:UFO religion
9102:Extremophile
9082:Biosignature
9077:Astroecology
9072:Astrobiology
9024:Great Filter
8839:Project Ozma
8747:Interstellar
8734:
8727:
8705:
8693:Perseverance
8692:
8684:
8614:
8601:
8584:
8577:
8570:
8472:Earth analog
8454:habitability
8437:Life on Mars
8224:
8156:
8134:
8113:
8103:
8067:
8048:
8024:
8005:
7986:
7976:
7954:
7944:
7923:
7902:
7883:
7877:. Cambridge.
7874:
7855:
7836:
7816:
7812:Stewart, Ian
7789:
7769:
7749:
7745:
7724:
7714:
7705:
7695:
7686:
7665:
7656:
7648:the original
7638:
7629:
7619:
7610:
7600:
7591:
7582:
7570:. Retrieved
7566:the original
7561:
7551:
7539:. Retrieved
7513:. Retrieved
7499:
7487:. Retrieved
7481:
7471:
7463:the original
7456:
7446:
7434:. Retrieved
7429:
7419:
7400:
7394:
7382:. Retrieved
7377:
7368:
7341:
7335:
7323:. Retrieved
7312:
7300:. Retrieved
7296:earthsky.org
7295:
7286:
7274:. Retrieved
7270:
7261:
7252:
7243:
7238:
7213:
7209:
7203:
7178:
7174:
7168:
7159:
7147:. Retrieved
7143:the original
7133:
7124:
7114:18 September
7112:. Retrieved
7101:
7083:
7076:
7043:
7040:Astrobiology
7039:
7033:
7025:
6995:
6991:
6978:
6969:
6963:
6954:
6945:
6933:. Retrieved
6929:
6920:
6900:
6893:
6875:
6868:
6841:
6837:
6823:
6811:. Retrieved
6807:
6794:
6782:. Retrieved
6778:
6769:
6760:
6751:
6727:. Retrieved
6723:the original
6713:
6704:
6699:Bennet, p. 5
6695:
6686:
6674:. Retrieved
6659:
6640:
6631:
6622:
6610:. Retrieved
6595:
6588:
6580:
6575:
6552:
6546:
6538:the original
6533:
6523:
6503:
6496:
6487:
6475:. Retrieved
6464:
6421:
6417:
6411:
6399:. Retrieved
6393:
6384:
6372:. Retrieved
6367:the original
6361:
6351:
6305:
6299:
6289:
6277:. Retrieved
6271:
6261:
6206:
6200:
6190:
6181:
6171:
6120:
6116:
6110:
6083:
6077:
6065:. Retrieved
6061:the original
6051:
6008:
6004:
6000:
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5978:
5966:. Retrieved
5962:the original
5952:
5943:
5933:
5921:. Retrieved
5915:
5893:
5883:
5874:
5865:
5840:
5836:
5830:
5824:Observatory.
5822:Optical SETI
5812:
5800:. Retrieved
5770:. Retrieved
5727:
5721:
5711:
5699:. Retrieved
5688:
5678:
5666:. Retrieved
5657:The Atlantic
5655:
5645:
5602:
5598:
5585:
5573:. Retrieved
5562:
5521:
5515:
5509:
5497:. Retrieved
5492:ScienceDaily
5490:
5481:
5469:. Retrieved
5440:. Retrieved
5436:the original
5421:
5376:
5372:
5362:
5350:. Retrieved
5346:
5336:
5324:. Retrieved
5318:
5308:
5296:. Retrieved
5282:
5268:
5259:
5249:
5237:. Retrieved
5233:the original
5223:
5190:
5187:Astrobiology
5186:
5180:
5139:
5135:
5128:
5108:
5086:. Retrieved
5080:
5070:
5058:. Retrieved
5052:
5042:
5001:
4997:
4975:. Retrieved
4971:the original
4939:. Retrieved
4931:
4921:
4909:. Retrieved
4895:
4883:. Retrieved
4877:
4867:
4855:. Retrieved
4845:
4812:
4808:
4795:
4786:
4761:
4757:
4747:
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4698:
4688:
4661:
4657:
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4613:
4603:
4570:
4566:
4556:
4531:
4527:
4516:
4504:. Retrieved
4500:
4491:
4466:
4462:
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4438:
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4399:
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4381:
4354:
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4285:
4242:
4238:
4232:
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4214:
4205:
4170:
4166:
4160:
4148:. Retrieved
4143:the original
4135:
4122:
4110:. Retrieved
4106:the original
4101:
4092:
4049:
4045:
4038:
4030:the original
3991:
3987:
3977:
3965:. Retrieved
3961:
3952:
3932:
3928:Stewart, Ian
3918:
3885:
3881:
3875:
3863:. Retrieved
3853:
3843:
3831:. Retrieved
3821:
3809:. Retrieved
3798:
3789:
3769:
3762:
3737:
3729:
3709:
3702:
3693:
3684:
3672:. Retrieved
3661:
3649:. Retrieved
3605:
3598:
3577:
3570:
3558:. Retrieved
3541:
3529:. Retrieved
3518:
3509:
3458:
3454:
3448:
3439:
3429:
3417:. Retrieved
3413:
3403:
3391:. Retrieved
3386:the original
3378:
3351:, retrieved
3319:
3309:
3258:
3255:Astrobiology
3254:
3244:
3217:
3213:
3189:, retrieved
3159:
3149:
3140:
3134:
3125:
3119:
3110:
3104:
3095:
3089:
3077:. Retrieved
3071:
3061:
3049:. Retrieved
3044:the original
3036:
3029:Davies, Paul
3023:
3011:. Retrieved
3005:
2993:
2973:
2964:
2955:
2949:K-type stars
2939:
2851:
2843:
2832:
2821:
2817:
2793:
2767:
2743:
2736:
2704:, discussed
2690:Seth Shostak
2657:", he said.
2640:
2621:
2604:
2592:
2588:
2547:
2504:
2482:
2479:astrobiology
2476:
2460:
2456:Solar System
2433:
2371:
2360:
2320:
2306:
2301:
2300:followed by
2297:
2287:
2276:19th century
2254:Solar System
2243:
2239:
2235:Isaac Newton
2228:
2209:
2173:started the
2160:
2151:
2135:philosopher
2130:
2106:
2098:
2079:Hari kshetra
2078:
2074:
2070:
2066:
2059:
2047:
2041:
2031:
2029:
2024:
1991:
1943:white dwarfs
1928:
1881:
1858:
1842:
1830:
1815:
1808:, the first
1806:Gliese 581 c
1778:biosignature
1765:
1748:Fossil fuels
1737:
1727:laser pulses
1716:
1700:civilization
1697:
1690:used by the
1627:
1616:
1613:protostellar
1602:
1570:hypoxanthine
1555:
1551:
1542:
1536:
1525:
1517:
1511:, formed of
1505:nanobacteria
1497:Solar System
1490:
1457:Solar System
1442:
1434:oceanography
1414:astrobiology
1411:
1408:Astrobiology
1384:
1379:
1373:
1346:
1335:
1330:life on Mars
1320:
1301:
1289:
1233:
1214:UV radiation
1207:
1194:biodiversity
1150:
1102:biochemistry
1099:
1019:
983:
947:
922:Zhi-Wei Wang
911:
905:
889:
881:
818:
815:
809:
802:
798:
787:
783:
776:
772:
765:
761:
751:
747:
731:
726:
717:
712:
584:devised the
579:
574:Solar System
567:
554:
528:
506:
494:hot Jupiters
477:
438:(and later,
413:
394:
297:Solar System
238:
199:
192:
176:
150:
143:
125:
121:astrobiology
88:
84:
80:
79:
43:
11939:Outer space
11878:Spaceflight
11778:Prix Guzman
11700:Jon Lomberg
11675:Frank Drake
11634:Cosmic Call
11566:Active SETI
11423:Outer space
11333:Cosmic dust
11298:Abiogenesis
11210:Unconfirmed
11166:Heavy water
11006:Ethanethiol
10921:Cyanoallene
10911:Acetic acid
10881:Methylamine
10765:Diacetylene
10680:Formic acid
10670:Cyanomethyl
10328:Diazenylium
10318:CCP radical
10194:(molecular)
10178:(molecular)
10147:(molecular)
9835:undeveloped
9685:BioSentinel
9575:Fobos-Grunt
9472:Earth orbit
9294:Biomolecule
9284:Abiogenesis
9277:Main topics
9211:Disciplines
9092:Exotheology
8904:Grey aliens
8757:Active SETI
8685:Opportunity
8565:BioSentinel
8383:Wow! signal
8332:KIC 8462852
8281:CI1 fossils
8096:Sagan, Carl
8084:|work=
7928:. Rutgers.
7808:Cohen, Jack
7515:14 February
7489:12 February
7181:(1): 3â34.
7110:. Space.com
6626:Crowe, p. 4
6374:4 September
5772:15 December
5701:15 December
5668:15 December
5088:28 February
5060:27 February
3924:Cohen, Jack
3670:. Space.com
3337:2434/266460
3079:18 February
3051:20 November
2945:G-type star
2731:Grey aliens
2706:Active SETI
2694:Frank Drake
2663:Yuri Milner
2600:Wow! signal
2499:abiogenesis
2446:Allen array
2340:abiogenesis
2268:, even the
2180:Tycho Brahe
2118:Middle Ages
2021:Anaximander
1916:brown dwarf
1865:light-years
1723:radio waves
1582:cosmic dust
1547:Gale Crater
1495:within the
1398:for study.
1391:water cycle
1342:Kuiper Belt
1295:other than
1134:prokaryotes
1078:Hydrosphere
1003:hydrocarbon
990:abiogenesis
793:intelligent
582:Frank Drake
488:planets or
461:abiogenesis
456:dust grains
138:references
101:prokaryotes
65:like Earth?
11888:Categories
11705:Carl Sagan
11680:Ann Druyan
11338:Cosmic ray
11280:Silylidyne
11243:Hemolithin
11218:Anthracene
11135:Deuterated
11116:Pyrimidine
10926:Ethanimine
10789:Ketenimine
10645:Butadiynyl
10469:Thioformyl
10323:Chloronium
9882:Red Dragon
9662:OSIRIS-REx
9646:Comets and
9349:Panspermia
9127:Noogenesis
9107:Hemolithin
8985:Panspermia
8933:Hypotheses
8909:Insectoids
8874:Water hole
8375:SHGb02+14a
8348:VVV-WIT-07
7541:25 January
7149:17 January
6972:: 134â135.
6279:5 November
5968:4 November
5923:30 January
5737:2301.05259
5499:27 October
5471:26 October
4885:8 February
4712:2001.00095
4664:: 103602.
4180:2109.10241
4150:29 October
4052:(1). 105.
2986:References
2919:Speciesism
2889:Hemolithin
2861:Haim Eshed
2788:See also:
2778:grey alien
2716:In fiction
2698:David Brin
2649:landed in
2634:, whereas
2611:Peter Ward
2567:Copernicus
2483:exobiology
2384:See also:
2137:Anaxagoras
2052:. Atomist
1984:The Greek
1959:See also:
1867:(1.3
1850:red dwarfs
1794:See also:
1558:meteorites
1501:meteorites
1453:identified
1451:have been
1445:exoplanets
1338:ice giants
1138:eukaryotes
1046:phosphorus
1005:, such as
942:See also:
743:our galaxy
547:Carl Sagan
490:Gas Giants
473:panspermia
465:meteoroids
152:Pre-modern
132:Democritus
85:alien life
63:exoplanets
61:Are there
18:Alien life
11854:Astronomy
11270:Phosphine
11138:molecules
11071:fullerene
10971:Acetamide
10775:Formamide
10655:Cyanamide
10509:Acetylene
10484:Tricarbon
10395:Methylene
10380:Isoformyl
10285:Triatomic
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