491:
307:
419:
38:
82:
2442:
550:
and pressures is much higher than previously thought imply that core cooling was largely by conduction not convection, limiting the ability of thermal convection to drive the geodynamo. This conundrum is known as the new "core paradox." An alternative process that could have sustained Earth's
586:. The rate of cooling by conduction and convection is uncertain, but one estimate is that the core would not be expected to freeze up for approximately 91 billion years, which is well after the Sun is expected to expand, sterilize the surface of the planet, and then burn out.
151:
of the outer core are about 3,000–4,500 K (2,700–4,200 °C; 4,900–7,600 °F) in its outer region and 4,000–8,000 K (3,700–7,700 °C; 6,700–14,000 °F) near the inner core. Modeling has shown that the outer core, because of its high temperature, is a
183:
As Earth's core cools, the liquid at the inner core boundary freezes, causing the solid inner core to grow at the expense of the outer core, at an estimated rate of 1 mm per year. This is approximately 80,000 tonnes of iron per second.
533:
with large uncertainties suggest that compositional and thermal convection contribute about 80 percent and 20 percent respectively to the power of Earth's geodynamo. Traditionally it was thought that prior to the formation of
385:
in Earth's outer core. For example, accretionary models based on core-mantle element partitioning tend to support proto-Earths constructed from reduced, condensed, and volatile-free material, despite the possibility that
422:
A diagram of Earth's differentiation. The light elements sulfur, silicon, oxygen, carbon, and hydrogen may constitute part of the outer core due to their abundance and ability to partition into liquid iron under certain
132:
are not transmitted through the outer core. Although having a composition similar to Earth's solid inner core, the outer core remains liquid as there is not enough pressure to keep it in a solid state.
225:
compose part of Earth's outer core, as the only feasible way to lower its density. Although Earth's outer core is inaccessible to direct sampling, the composition of light
603:
353:
in BSE compared to CI meteorites may indicate that silicon was absorbed into Earth's core; however, a wide range of silicon concentrations in Earth's outer and
1717:"Accretion and differentiation of the terrestrial planets with implications for the compositions of early-formed Solar System bodies and accretion of water"
582:
The magnetic field generated by core flow is essential to protect life from interplanetary radiation and prevent the atmosphere from dissipating in the
2213:
435:
compared to chondritic meteorites is attributed to metal-silicate reactions during formation of Earth's core. These reactions are dependent on
995:
Wassel, Lauren; Irving, Jessica; Dues, Arwen (2011). "Reconciling the hemispherical structure of Earth's inner core with its super-rotation".
517:
and also by chemical convection, the exclusion of light elements from the inner core, which float upward within the fluid outer core while
410:
in Earth's outer core, models of Earth's accretion that match these concentrations would presumably better constrain Earth’s formation.
1338:
Mittal, Tushar; Knezek, Nicholas; Arveson, Sarah M.; McGuire, Chris P.; Williams, Curtis D.; Jones, Timothy D.; Li, Jie (2020-02-15).
2279:
494:
A diagram of Earth's geodynamo and magnetic field, which could have been driven in Earth's early history by the crystallization of
868:
De Wijs, Gilles A.; Kresse, Georg; Vočadlo, Lidunka; Dobson, David; Alfè, Dario; Gillan, Michael J.; Price, Geoffrey D. (1998).
2422:
144:
constrain the radius of the outer core to be 3483 km with an uncertainty of 5 km, while that of the inner core is 1220±10 km.
2093:
Tagawa, Shoh; Sakamoto, Naoya; Hirose, Kei; Yokoo, Shunpei; Hernlund, John; Ohishi, Yasuo; Yurimoto, Hisayoshi (2021-05-11).
919:
771:
428:
365:
Tighter constraints on the concentrations of light elements in Earth's outer core would provide a better understanding of
611:
318:. Namely, the light elements contained must have been abundant during Earth's formation, must be able to partition into
2022:"High-Resolution Simulations of The Final Assembly of Earth-Like Planets. 2. Water Delivery And Planetary Habitability"
490:
849:
2466:
2445:
1711:
Rubie, D. C.; Jacobson, S. A.; Morbidelli, A.; O’Brien, D. P.; Young, E. D.; de Vries, J.; Nimmo, F.; Palme, H.;
2369:
1856:
1712:
1637:
Dauphas, Nicolas; Poitrasson, Franck; Burkhardt, Christoph; Kobayashi, Hiroshi; Kurosawa, Kosuke (2015-10-01).
349:
can provide insights into the light element composition of Earth's outer core. For instance, the depletion of
31:
1519:"Shock compression of Fe-Ni-Si system to 280 GPa: Implications for the composition of the Earth's outer core"
660:"Shock compression of Fe-Ni-Si system to 280 GPa: Implications for the composition of the Earth's outer core"
2272:
1956:
94:
1859:; Harries, Dennis; Langenhorst, Falko; Miyajima, Nobuyoshi; Pollok, Kilian; Rubie, David C. (2015-10-15).
2288:
370:
716:
944:
Buffett, Bruce A. (2010). "Tidal dissipation and the strength of the Earth's internal magnetic field".
841:
514:
205:
of Earth's outer core. In fact, Earth's outer core is approximately 5 to 10 percent lower density than
17:
1909:
1716:
1638:
1517:
Zhang, Youjun; Sekine, Toshimori; He, Hongliang; Yu, Yin; Liu, Fusheng; Zhang, Mingjian (2014-07-15).
1471:
1398:
Zhang, Youjun; Sekine, Toshimori; He, Hongliang; Yu, Yin; Liu, Fusheng; Zhang, Mingjian (2016-03-02).
658:
Zhang, Youjun; Sekine, Toshimori; He, Hongliang; Yu, Yin; Liu, Fusheng; Zhang, Mingjian (2014-07-15).
1470:
Suer, Terry-Ann; Siebert, Julien; Remusat, Laurent; Menguy, Nicolas; Fiquet, Guillaume (2017-07-01).
568:
510:
169:
1785:
Badro, James; Brodholt, John P.; Piet, Hélène; Siebert, Julien; Ryerson, Frederick J. (2015-10-06).
2389:
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471:
463:
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366:
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238:
65:
64:. The outer core begins approximately 2,889 km (1,795 mi) beneath Earth's surface at the
2379:
2374:
2265:
535:
381:
Models of Earth's accretion could be better tested if we had better constraints on light element
2166:
869:
27:
Fluid layer composed of mostly iron and nickel between Earth's solid inner core and its mantle
2471:
2427:
2351:
538:, Earth's geodynamo was mainly driven by thermal convection. However, recent claims that the
354:
118:
57:
1982:
1925:
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1487:
1355:
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2178:
2106:
2043:
1978:
1921:
1872:
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1660:
1639:"Planetary and meteoritic Mg/Si and δ30Si variations inherited from solar nebula chemistry"
1587:
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1293:
1221:
1085:
1046:
1004:
953:
884:
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728:
671:
572:
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of these elements in Earth's outer core will help elucidate the conditions of formation of
282:
68:
and ends 5,150 km (3,200 mi) beneath Earth's surface at the inner core boundary.
2231:
2021:
1787:"Core formation and core composition from coupled geochemical and geophysical constraints"
634:
8:
2333:
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2182:
2110:
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2002:
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1399:
1377:
1253:
1181:
977:
900:
813:
788:
697:
1472:"A sulfur-poor terrestrial core inferred from metal–silicate partitioning experiments"
1281:
314:
The variety of light elements present in Earth's outer core is constrained in part by
137:
2415:
2307:
2194:
2140:
2122:
2067:
2059:
1994:
1937:
1890:
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432:
310:
An artist's illustration of what Earth might have looked like early in its formation.
61:
2079:
2006:
1766:
1688:
2302:
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2130:
2114:
2051:
1986:
1929:
1880:
1824:
1806:
1746:
1668:
1623:
1595:
1574:
Georg, R. Bastian; Halliday, Alex N.; Schauble, Edwin A.; Reynolds, Ben C. (2007).
1538:
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1435:
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2118:
1933:
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563:, and other light elements. As the Earth's core began to cool, it would become
503:
173:
48:
is a fluid layer about 2,260 km (1,400 mi) thick, composed of mostly
1885:
1860:
1575:
1209:
551:
geodynamo requires Earth's core to have initially been hot enough to dissolve
37:
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2126:
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1998:
1941:
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1680:
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1177:
870:"The viscosity of liquid iron at the physical conditions of the Earth's core"
822:
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526:
448:
382:
222:
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391:
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177:
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326:, and must not volatilize and escape during Earth's accretionary process.
2038:
1543:
1518:
684:
659:
547:
479:
278:
210:
197:
Earth's outer core cannot be entirely constituted of iron or iron-nickel
148:
1599:
1340:"Precipitation of multiple light elements to power Earth's early dynamo"
1233:
965:
418:
201:
because their densities are higher than geophysical measurements of the
81:
1861:"High pressure metal–silicate partitioning of Ni, Co, V, Cr, Si, and O"
583:
157:
122:
2214:"Earth's core cooling faster than previously thought, researchers say"
1957:"On the water delivery to terrestrial embryos by ice pebble accretion"
1423:
1400:"Experimental constraints on light elements in the Earth's outer core"
168:
in the nickel-iron fluid of the outer core as the principal source of
2257:
1016:
556:
337:
are believed to contain the same planet-forming elements in the same
334:
242:
153:
2095:"Experimental evidence for hydrogen incorporation into Earth's core"
2217:
2020:
Raymond, Sean N.; Quinn, Thomas; Lunine, Jonathan I. (2007-02-01).
1973:
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399:
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may have been absorbed into core-forming metals through a hydrous
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249:. Recent estimates are that Earth's outer core is composed of
1573:
1282:"Light elements in the Earth's outer core: A critical review"
1208:
Wood, Bernard J.; Walter, Michael J.; Wade, Jonathan (2006).
576:
475:
467:
387:
361:
Implications for Earth's accretion and core formation history
338:
198:
1855:
Fischer, Rebecca A.; Nakajima, Yoichi; Campbell, Andrew J.;
1854:
180:, 50 times stronger than the magnetic field at the surface.
543:
250:
206:
121:, which is solid. Evidence for a fluid outer core includes
49:
1955:
Sato, Takao; Okuzumi, Satoshi; Ida, Shigeru (2016-05-01).
1337:
867:
485:
413:
2092:
920:"First Measurement Of Magnetic Field Inside Earth's Core"
1784:
1469:
579:
leading to a different variant of chemical convection.
285:
and the inner core boundary ranges from 4,137 to 4,300
187:
610:. National Geographic. 18 January 2017. Archived from
176:
strength in Earth's outer core is estimated to be 2.5
1910:"Core formation and the oxidation state of the Earth"
1152:
Hirose, Kei; Wood, Bernard; VoÄŤadlo, Lidunka (2021).
1035:"Elasticity and constitution of the Earth's interior"
838:
Global earth physics a handbook of physical constants
398:. If we could better constrain the concentrations of
376:
1210:"Accretion of the Earth and segregation of its core"
2019:
1151:
793:Monthly Notices of the Royal Astronomical Society
521:elements sink. This chemical convection releases
2458:
994:
93: with: speed of convection. You can help by
1791:Proceedings of the National Academy of Sciences
1516:
1397:
657:
633:Sue, Caryl (2015-08-17). Evers, Jeannie (ed.).
1954:
1207:
2273:
721:Annual Review of Earth and Planetary Sciences
458:In another example, the possible presence of
1286:Physics of the Earth and Planetary Interiors
1074:"Density and composition of mantle and core"
917:
2211:
863:
861:
345:, so differences between CI meteorites and
2280:
2266:
789:"The Rigidity of the Earth's Central Core"
2134:
2037:
1972:
1884:
1828:
1810:
1732:
1654:
1542:
1439:
1363:
812:
761:
683:
1907:
988:
858:
786:
714:
567:in these light elements that would then
489:
462:in Earth's outer core suggests that the
417:
305:
229:can be meaningfully constrained by high-
217:. Hence it has been proposed that light
36:
30:For broader coverage of this topic, see
2164:
1279:
943:
486:Implications for Earth's magnetic field
470:was not limited to the final stages of
414:Consequences for Earth's core formation
394:was accreted towards the conclusion of
32:Internal structure of Earth § Core
14:
2459:
2287:
1850:
1848:
1780:
1778:
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1158:Nature Reviews Earth & Environment
1147:
1145:
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1139:
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1135:
1133:
1131:
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835:
529:that produces Earth's magnetic field.
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1706:
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1465:
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1111:
1109:
1107:
1071:
1032:
1028:
1026:
1908:Wade, J.; Wood, B. J. (2005-07-30).
1510:
1154:"Light elements in the Earth's core"
766:. Academic Press. pp. 101–118.
525:that is then available to power the
188:Light elements of Earth's outer core
75:
1914:Earth and Planetary Science Letters
1845:
1773:
1643:Earth and Planetary Science Letters
1476:Earth and Planetary Science Letters
1344:Earth and Planetary Science Letters
741:10.1146/annurev.ea.15.050187.000325
632:
233:experiments, calculations based on
24:
2151:
1695:
1456:
1388:
1320:
1264:
1192:
1104:
1065:
1023:
814:10.1111/j.1365-246X.1926.tb05385.x
651:
377:Consequences for Earth's accretion
25:
2483:
2253:
1280:Poirier, Jean-Paul (1994-09-01).
918:Staff writer (17 December 2010).
2441:
2440:
2385:D’’ discontinuity (lower mantle)
2380:660 discontinuity (upper mantle)
2375:410 discontinuity (upper mantle)
2167:"Earth's Core and the Geodynamo"
2165:Buffett, Bruce A. (2000-06-16).
840:(3rd ed.). Washington, DC:
787:Jeffreys, Harold (1 June 1926).
329:
243:carbonaceous chondrite meteorite
80:
2224:
2212:David K. Li (19 January 2022).
2205:
2086:
2013:
1948:
1901:
1865:Geochimica et Cosmochimica Acta
1630:
1567:
1078:Journal of Geophysical Research
1039:Journal of Geophysical Research
937:
836:Ahrens, Thomas J., ed. (1995).
764:Physics of the Earth's interior
911:
829:
780:
755:
708:
626:
596:
296:
192:
56:that lies above Earth's solid
41:Earth and atmosphere structure
13:
1:
2191:10.1126/science.288.5473.2007
1576:"Silicon in the Earth's core"
1072:Birch, Francis (1964-10-15).
589:
253:along with 0 to 0.26 percent
71:
1961:Astronomy & Astrophysics
1751:10.1016/j.icarus.2014.10.015
1523:Geophysical Research Letters
1306:10.1016/0031-9201(94)90120-1
664:Geophysical Research Letters
301:
7:
1991:10.1051/0004-6361/201527069
715:Young, C J; Lay, T (1987).
639:National Geographic Society
447:, so better constraints on
113:The outer core of Earth is
10:
2488:
2370:Mohorovičić (crust–mantle)
2119:10.1038/s41467-021-22035-0
1934:10.1016/j.epsl.2005.05.017
1673:10.1016/j.epsl.2015.07.008
1496:10.1016/j.epsl.2017.04.016
1365:10.1016/j.epsl.2019.116030
1170:10.1038/s43017-021-00203-6
842:American Geophysical Union
717:"The Core-Mantle Boundary"
29:
2436:
2403:
2362:
2295:
1886:10.1016/j.gca.2015.06.026
247:bulk silicate Earth (BSE)
2423:Gutenberg (upper mantle)
2404:Regional discontinuities
2056:10.1089/ast.2006.06-0126
762:Gutenberg, Beno (2016).
608:Science & Innovation
390:material from the outer
335:CI chondritic meteorites
289:and from 5,400 to 6,300
237:measurements, models of
1983:2016A&A...589A..15S
1926:2005E&PSL.236...78W
1812:10.1073/pnas.1505672112
1665:2015E&PSL.427..236D
1488:2017E&PSL.469...84S
1356:2020E&PSL.53216030M
1098:10.1029/JZ069i020p04377
1059:10.1029/JZ057i002p00227
1033:Birch, Francis (1952).
2467:Structure of the Earth
2428:Lehmann (upper mantle)
2363:Global discontinuities
511:Earth's magnetic field
507:
424:
311:
170:Earth's magnetic field
136:Seismic inversions of
42:
2099:Nature Communications
493:
421:
309:
261:, 0.8 to 5.3 percent
40:
2390:Core–mantle boundary
1544:10.1002/2014gl060670
685:10.1002/2014gl060670
540:thermal conductivity
523:gravitational energy
429:siderophile elements
283:core-mantle boundary
156:fluid that convects
66:core-mantle boundary
2395:Inner-core boundary
2318:Lithospheric mantle
2236:National Geographic
2183:2000Sci...288.2007B
2177:(5473): 2007–2012.
2111:2021NatCo..12.2588T
2048:2007AsBio...7...66R
1877:2015GeCoA.167..177F
1803:2015PNAS..11212310B
1797:(40): 12310–12314.
1743:2015Icar..248...89R
1600:10.1038/nature05927
1592:2007Natur.447.1102G
1586:(7148): 1102–1106.
1535:2014GeoRL..41.4554Z
1416:2016NatSR...622473Z
1298:1994PEPI...85..319P
1234:10.1038/nature04763
1226:2006Natur.441..825W
1090:1964JGR....69.4377B
1051:1952JGR....57..227B
1009:2011NatGe...4..264W
966:10.1038/nature09643
958:2010Natur.468..952B
889:1998Natur.392..805D
805:1926GeoJ....1..371J
733:1987AREPS..15...25Y
676:2014GeoRL..41.4554Z
531:Carnot efficiencies
357:is still possible.
277:by weight, and the
265:, 0 to 4.0 percent
2289:Structure of Earth
1404:Scientific Reports
604:"Earth's Interior"
536:Earth's inner core
515:thermal convection
508:
425:
312:
147:Estimates for the
46:Earth's outer core
43:
2454:
2453:
2416:continental crust
1529:(13): 4554–4559.
1424:10.1038/srep22473
1220:(7095): 825–833.
1084:(20): 4377–4388.
997:Nature Geoscience
773:978-1-4832-8212-1
670:(13): 4554–4559.
472:Earth's accretion
427:The depletion of
396:Earth's accretion
367:Earth's accretion
316:Earth's accretion
245:comparisons with
239:Earth's accretion
125:which shows that
111:
110:
16:(Redirected from
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2039:astro-ph/0510285
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341:as in the early
273:, and 5 percent
209:at Earth's core
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21:
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504:iron(II) oxide
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117:, unlike its
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2472:Geomagnetism
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2330:Lower mantle
2313:Upper mantle
2239:. Retrieved
2226:
2207:
2174:
2170:
2102:
2098:
2088:
2032:(1): 66–84.
2029:
2026:Astrobiology
2025:
2015:
1964:
1960:
1950:
1920:(1): 78–95.
1917:
1913:
1903:
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1713:Frost, D. J.
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724:
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642:. Retrieved
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616:. Retrieved
612:the original
607:
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581:
573:lower mantle
548:temperatures
509:
457:
453:Earth's core
426:
392:Solar System
380:
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343:Solar System
333:
322:iron at low
313:
211:temperatures
196:
182:
146:
142:normal modes
135:
112:
99:
95:adding to it
90:
45:
44:
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1871:: 177–194.
1649:: 236–248.
929:14 November
924:Science 2.0
799:: 371–383.
618:14 November
569:precipitate
480:magma ocean
466:of Earth’s
423:conditions.
339:proportions
297:Constraints
279:temperature
193:Composition
158:turbulently
149:temperature
130:shear-waves
2461:Categories
2352:Inner core
2347:Outer core
2334:Mesosphere
1974:1512.02414
1727:: 89–108.
1656:1507.02922
1350:: 116030.
644:2022-02-25
590:References
584:solar wind
355:inner core
178:millitesla
138:body waves
123:seismology
119:inner core
72:Properties
58:inner core
18:Outer core
2127:2041-1723
2064:1531-1074
1999:0004-6361
1942:0012-821X
1895:0016-7037
1821:0027-8424
1759:0019-1035
1734:1410.3509
1681:0012-821X
1608:1476-4687
1561:128528504
1553:0094-8276
1504:0012-821X
1482:: 84–97.
1432:2045-2322
1382:213919815
1374:0012-821X
1314:0031-9201
1242:1476-4687
1186:237272150
1178:2662-138X
905:205003051
823:1365-246X
749:0084-6597
702:128528504
694:0094-8276
571:into the
557:magnesium
527:geodynamo
474:and that
464:accretion
373:history.
324:pressures
302:Accretion
221:with low
215:pressures
154:viscosity
102:July 2019
2446:Category
2218:NBC News
2199:10856207
2145:33976113
2080:10257401
2072:17407404
2007:55107839
1839:26392555
1767:37592339
1689:20744455
1616:17597757
1450:26932596
1250:16778882
974:21164483
575:forming
546:at core
460:hydrogen
400:hydrogen
388:oxidized
255:hydrogen
231:pressure
227:elements
219:elements
2241:15 July
2179:Bibcode
2171:Science
2136:8113257
2107:Bibcode
2044:Bibcode
1979:Bibcode
1967:: A15.
1922:Bibcode
1873:Bibcode
1830:4603515
1799:Bibcode
1739:Bibcode
1661:Bibcode
1624:1892924
1588:Bibcode
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1484:Bibcode
1441:4773879
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1294:Bibcode
1258:8942975
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1086:Bibcode
1047:Bibcode
1005:Bibcode
982:4431270
954:Bibcode
885:Bibcode
801:Bibcode
729:Bibcode
672:Bibcode
561:silicon
441:silicon
408:silicon
351:silicon
281:of the
267:silicon
235:seismic
203:density
127:seismic
2411:Conrad
2308:Mantle
2296:Shells
2232:"Core"
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2005:
1997:
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877:Nature
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635:"Core"
577:oxides
553:oxygen
519:denser
502:, and
445:sulfur
443:, and
437:oxygen
406:, and
404:oxygen
320:liquid
275:nickel
271:sulfur
263:oxygen
259:carbon
241:, and
160:. The
115:liquid
62:mantle
54:nickel
2332:(aka
2303:Crust
2076:S2CID
2034:arXiv
2003:S2CID
1969:arXiv
1763:S2CID
1729:arXiv
1685:S2CID
1651:arXiv
1620:S2CID
1557:S2CID
1378:S2CID
1254:S2CID
1182:S2CID
978:S2CID
901:S2CID
873:(PDF)
698:S2CID
476:water
468:water
199:alloy
164:sees
2342:Core
2243:2024
2195:PMID
2141:PMID
2123:ISSN
2068:PMID
2060:ISSN
1995:ISSN
1938:ISSN
1891:ISSN
1835:PMID
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1446:PMID
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1174:ISSN
970:PMID
931:2018
846:ISBN
819:ISSN
768:ISBN
745:ISSN
690:ISSN
620:2018
544:iron
369:and
251:iron
213:and
207:iron
152:low-
140:and
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50:iron
2187:doi
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2131:PMC
2115:doi
2052:doi
1987:doi
1965:589
1930:doi
1918:236
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1669:doi
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