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193:, under flat conditions (without obstructions like mountains or at a height above any such obstructions), the terminator moves at approximately 463 metres per second (1,040 mph). This speed can appear to increase when near obstructions, such as the height of a mountain, as the shadow of the obstruction will be cast over the ground in advance of the terminator along a flat landscape. The speed of the terminator decreases as it approaches the poles, where it can reach a speed of zero (full-day sunlight or darkness).
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can create a fuzzier terminator. As the particles within an atmosphere are at a higher elevation, the light source can remain visible even after it has set at ground level. These particles scatter the light, reflecting some of it to the ground. Hence, the sky can remain illuminated even after the sun
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and other geological features are elongated, thereby making such features more apparent to the observer. This phenomenon is similar to the lengthening of shadows on Earth when the Sun is low in the sky. For this reason, much lunar photographic study centers on the illuminated area near the lunar
508:. This prolongs the operational life of a LEO satellite, as onboard battery life is prolonged. It also enables specific experiments that require minimum interference from the Sun, as the designers can opt to install the relevant sensors on the dark side of the satellite.
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has set. Images showing a planetary terminator can be used to map topography: the position of the tip of a mountain behind the terminator line is measured when the Sun still or already illuminates it while the base of the mountain remains in shadow.
437:, although the Moon's much lower rate of rotation means it takes longer for it to pass across the surface. At the equator, it moves at 15.4 kilometres per hour (9.6 mph), as fast as an athletic human can run on earth.
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135:. The circle separates the portion of Earth experiencing daylight from that experiencing darkness (night). While a little over one half of Earth is illuminated at any point in time (with exceptions during
303:
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115:, the terminator is a circle with a diameter that is approximately that of Earth. The terminator passes through any point on Earth's surface twice a day, at
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are the only aircraft able to overtake the maximum speed of the terminator at the equator. However, slower vehicles can overtake the terminator at higher
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473:, but does not appear to do so. The illusion results from misinterpreting the arrangement of objects in the sky according to intuition based on
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operators take advantage of conditions along the terminator to perform long-distance communications. Called "gray-line" or "grey-line"
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Examination of a terminator can yield information about the surface of a planetary body; for example, the presence of an
804:– Website calculating synthetic images (B&W or color) representing the terminator for a given time (date & hour)
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arising from the expectation of an observer on Earth that the direction of sunlight illuminating the Moon (i.e. a line
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revolution around the Sun; thus, the plane of the terminator is nearly parallel to planes created by lines of
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satellites take advantage of the fact that certain polar orbits set near the terminator do not suffer from
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329:. The terminator is diffuse and shows the gradual transition to darkness that is experienced as
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A photograph of part of the terminator crossing the surface of the Earth, as seen from the
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are continuously lit by sunlight. Such orbits are called dawn-dusk orbits, a type of
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675:), so the terminator moves across the lunar surface at 15.4 kilometers per hour.
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into a unique intermediate state along the terminator, called the "grey line".
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The transition from light to dark takes place on two fronts in this image of
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terminator, and the resulting shadows provide accurate descriptions of the
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Ionospheric
Propagation, Transmission Lines, and Antennas for the QRP DXer
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A seasonal animation of the terminator line at sunset over central Europe.
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537:
527:
132:
686:
624:, pp. 1–16, 1-22–1-24. Green Valley, AZ: Milliwatt QRP Books.
276:. Under good conditions, radio waves can travel along the terminator to
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is the division between the illuminated and dark hemispheres of the
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on its axis. The terminator path also varies by time of year due to
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85:. An observer on the terminator of such an orbiting body with an
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where this only occurs when the point is not experiencing
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155:, and its maximum angle is approximately 23.5° to the
425:. It is the lunar equivalent of the division between
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258:take longer to form. This time-difference puts the
557:Mackenzie, Fred T.; Lerman, Abraham (2006-12-29).
444:strikes this portion of the Moon, shadows cast by
1016:
77:where the line through the center of its parent
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27:Line dividing day and night on a celestial body
469:to the terminator) should correspond with the
461:The lunar terminator (or tilt) illusion is an
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632:
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234:changes between day- and night-side of the
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711:Myers-Beaghton, Andrea K.; Myers, Alan L.
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365:An oblique view of the large lunar crater
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672:cycle is 29.53 Earth days in length (see
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563:. Springer Science & Business Media.
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685:Jones, Christopher B. (January 2014).
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385:crater while at the terminator (from
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41:Earth's terminator as seen from space
808:The Moon Terminator Illusion (video)
401:photos along the terminator showing
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65:. The terminator is defined as the
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611:by David Harry Grinspoon, page 329
53:is a moving line that divides the
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731:"Cloud-base or mountain shadow?"
729:Furger, Markus (February 2009).
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185:as it approaches the terminator.
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691:Ellipsis: unfinished thought..
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652:"List of basic lunar features"
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348:crater near the terminator on
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1:
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95:light scattering by particles
181:Video of the Earth from the
7:
687:"Lunar Terminator Illusion"
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226:Grey-line radio propagation
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585:"SOS:Day Night Terminator"
440:Due to the angle at which
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104:
29:
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893:
882:
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533:Lunar grazing occultation
457:Lunar terminator illusion
713:"The Moon Tilt Illusion"
369:at the terminator (from
30:For other meanings, see
481:Scientific significance
620:Adrian Weiss. (2011).
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244:high frequency signals
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97:in the gaseous layer.
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506:Sun-synchronous orbit
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212:supersonic transports
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167:Surface transit speed
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747:2009Wthr...64...53F
471:position of the Sun
274:skywave propagation
197:Supersonic aircraft
800:2006-12-05 at the
790:Current terminator
500:, therefore their
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101:Earth's terminator
57:side and the dark
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381:The east side of
232:radio propagation
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89:would experience
16:(Redirected from
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654:. Archived from
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587:. Archived from
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463:optical illusion
419:lunar terminator
357:Lunar terminator
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141:Earth's rotation
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18:Lunar terminator
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1035:Solar phenomena
1025:Earth phenomena
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69:of points on a
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1040:Parts of a day
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658:on 2006-02-03.
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63:planetary body
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638:"Propagation"
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591:on 2009-02-06
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467:perpendicular
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451:lunar terrain
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51:twilight zone
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994:Midnight sun
978:
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694:. Retrieved
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656:the original
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593:. Retrieved
589:the original
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523:Ground track
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264:
230:Strength of
229:
201:jet fighters
195:
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129:midnight sun
110:
50:
46:
44:
999:Polar night
974:Golden hour
843:Parts of a
538:Lunar phase
528:Colongitude
502:solar cells
270:propagation
159:during the
151:during the
133:polar night
1019:Categories
979:Terminator
595:2009-02-06
544:References
487:atmosphere
411:Bullialdus
407:Lubiniezky
397:Mosaic of
383:Timocharis
260:ionosphere
254:above the
236:ionosphere
105:See also:
87:atmosphere
61:side of a
47:terminator
32:Terminator
989:Moonlight
923:Blue hour
871:Afternoon
773:120609206
765:0043-1656
741:(2): 53.
670:lunar day
399:Apollo 16
387:Apollo 15
371:Apollo 13
346:Boznańska
278:antipodal
220:equinoxes
216:latitudes
161:solstices
153:equinoxes
149:longitude
984:Daylight
941:Midnight
895:Twilight
798:Archived
512:See also
442:sunlight
435:spheroid
331:twilight
280:points.
252:F layers
205:Concorde
137:eclipses
91:twilight
962:Related
908:Sunrise
876:Evening
861:Morning
853:Daytime
743:Bibcode
735:Weather
498:eclipse
446:craters
413:craters
350:Mercury
284:Gallery
256:D layer
240:D layer
191:equator
189:At the
119:and at
117:sunrise
93:due to
83:tangent
913:Sunset
771:
763:
696:21 May
567:
409:, and
403:Darney
367:Keeler
121:sunset
71:planet
55:daylit
1030:Light
933:Night
769:S2CID
716:(PDF)
427:night
311:Mimas
248:the E
199:like
113:Earth
67:locus
59:night
918:Dusk
903:Dawn
866:Noon
761:ISSN
698:2016
668:The
565:ISBN
429:and
423:Moon
417:The
250:and
207:and
157:pole
79:star
75:moon
845:day
751:doi
431:day
327:ISS
203:or
183:ISS
131:or
111:On
81:is
73:or
49:or
1021::
767:.
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739:64
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629:^
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Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
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