384:
356:
346:) from the surface of the Earth. Hence there will always be a delay of at least a quarter of a second in a communication via geostationary satellite (119.4 ms times 2); this delay is just perceptible in a transoceanic telephone conversation routed by satellite. The answer will also be delayed with a quarter of a second and this is clearly noticeable during interviews or discussions on TV when sent over satellite.
498:, has an interstellar velocity of 3.57 AU per year, or 29.7 light-minutes per year. As of 2023 the probe, launched in 1977, is over 22 light-hours from Earth and the Sun, and is expected to reach a distance of one light-day around November 2026 – February 2027.
1119:
489:
1112:
383:
1290:
1105:
355:
989:
953:
419:(roughly the distance between Earth and the Sun) in light-seconds is a fundamental measurement for the calculation of modern
478:
A light-minute is 60 light-seconds, and so the average distance between Earth and the Sun is 8.317 light-minutes.
1259:
1143:
411:
data used to determine them. (The match is not exact for an Earth-based observer because of a very small correction for
101:
940:
449:
913:
259:
or just under one international foot) to the light-minute, light-hour and light-day, which are sometimes used in
1285:
335:
318:
in free space. Distances in fractions of a light-second are useful for planning telecommunications networks.
886:
279:
1254:
866:
470:
Multiples of the light-second can be defined, although apart from the light-year, they are more used in
424:
359:
The yellow shell indicating one light-day distance from the Sun compares in size with the positions of
1053:
387:
The faint yellow sphere centred on the Sun has a radius of one light-minute. For comparison, sizes of
379:'s orbit (faint orange ellipse below). Click on the image for a larger view and links to other scales.
423:(tables of planetary positions). It is usually quoted as "light-time for unit distance" in tables of
189:
1264:
1156:
343:
332:
The mean distance, over land, between opposite sides of the Earth is 66.8 light-milliseconds.
283:
185:
148:
1201:
985:
463:
416:
116:
862:
396:
322:
One light-nanosecond is almost 300 millimetres (299.8 mm, 5 mm less than one
917:
471:
376:
339:
260:
395:(the red star in the top right) are shown to scale. The large yellow ellipse represents
1128:
881:
315:
177:
144:
960:
1279:
412:
323:
1097:
1182:
928:
404:
326:), which limits the speed of data transfer between different parts of a computer.
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372:
1237:
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1225:
1213:
891:
797:
566:
Average distance from the Earth to the Moon is about 1.282 light-seconds
408:
367:
264:
201:
125:
1207:
1195:
1132:
978:
McCarthy, Dennis D.; Petit, Gérard, eds. (2004). "IERS Conventions (2003)".
737:
494:
420:
392:
361:
181:
17:
403:
The light-second is a convenient unit for measuring distances in the inner
371:(red and green arrows respectively). It is larger than the heliosphere's
193:
73:
616:
Average distance from the Earth to the Sun is 8.317 light-minutes
910:
1219:
674:
252:
205:
134:
41:
800:
is thought to extend between 41 and 82 light-weeks out from the Sun
678:
670:
482:
388:
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311:
218:
197:
90:
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1029:
1005:
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248:
240:
164:
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297:
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is about 0.94 light-days from the Sun (as of April 2024)
441:
The mean diameter of Earth is about 0.0425 light-seconds.
251:, the light-second can form the basis for other units of
1030:"Pluto distance from sun in light hours - Wolfram|Alpha"
984:. Frankfurt: Bundesamts für Kartographie und Geodäsie.
247:
Just as the second forms the basis for other units of
1078:"3.57 au/year in light-minutes/year - Wolfram|Alpha"
462:
The average distance between Earth and the Sun (the
267:is also currently defined to be equal to precisely
140:
97:
69:
47:
37:
32:
954:"JPL Planetary and Lunar Ephemerides, DE405/LE405"
474:publications than in research works. For example:
931:suggested one light-nanosecond might be called a
329:One light-microsecond is about 300 metres.
278:, since the definition of a year is based on a
1113:
8:
485:and the Sun (34.72 AU) is 4.81 light-hours.
444:The average distance between Earth and the
407:, since it corresponds very closely to the
1120:
1106:
1098:
29:
1006:"Pluto distance from sun - Wolfram|Alpha"
869:to the Sun, about 4.24 light years away
501:
338:are typically 1.337 light-milliseconds (
903:
959:. JPL IOM 312.F-98-048. Archived from
427:, and its currently accepted value is
263:publications. The more commonly used
255:, ranging from the light-nanosecond (
7:
911:IAU Recommendations concerning Units
391:(the blue star in the top left) and
25:
1291:Units of measurement in astronomy
51:
981:IERS Technical Note No. 32
452:) is about 1.282 light-seconds.
342:) to 119.4 light-milliseconds (
314:rarely travel at precisely the
375:(blue shell) but smaller than
1:
481:The average distance between
459:is about 4.643 light-seconds.
1260:Orders of magnitude (length)
1144:Astronomical system of units
1307:
941:Princeton University Press
681:is about 1.25 light-hours
310:Communications signals on
208:, and is equal to exactly
1247:
1152:
1139:
513:
510:
507:
504:
490:distant artificial object
466:) is 499.0 light-seconds.
413:the effects of relativity
336:Communications satellites
306:Use in telecommunications
65:
952:Standish, E. M. (1998).
887:Geometrized unit system
511:Equivalent distance in
192:. It is defined as the
1255:Cosmic distance ladder
1054:"Voyager - Fast Facts"
425:astronomical constants
400:
380:
386:
358:
1082:www.wolframalpha.com
1058:voyager.jpl.nasa.gov
1034:www.wolframalpha.com
1010:www.wolframalpha.com
455:The diameter of the
415:.) The value of the
190:relativistic physics
53:1 light-second
1265:Conversion of units
344:geostationary orbit
276: light-seconds
60:... is equal to ...
916:2007-02-16 at the
401:
381:
290:, each of exactly
186:telecommunications
155:
142:
107:
102:astronomical units
99:
79:
71:
1273:
1272:
1202:Astronomical unit
873:
872:
808:365.25 light-days
464:astronomical unit
417:astronomical unit
373:termination shock
170:
169:
48:Conversions
16:(Redirected from
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863:Proxima Centauri
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827:
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624:60 light-minutes
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574:60 light-seconds
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488:Humanity's most
436:
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351:Use in astronomy
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1286:Units of length
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1275:
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1188:
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1162:
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1129:Units of length
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937:It's About Time
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918:Wayback Machine
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533:1 light-second
472:popular science
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377:Comet Hale-Bopp
353:
340:low Earth orbit
308:
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261:popular science
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222:(approximately
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966:on 2012-02-20.
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935:at page 22 of
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882:100 megametres
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820:light-seconds
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757:light-seconds
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698:light-seconds
689:24 light-hours
687:
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631:
630:light-seconds
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450:lunar distance
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316:speed of light
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284:Gregorian year
178:unit of length
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27:Unit of length
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991:3-89888-884-3
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580:light-minute
573:
571:light-minute
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530:light-second
529:
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288:365.25 d
286:) of exactly
285:
281:
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257:299.8 mm
254:
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129: 9.7156
127:
120: 3.1688
118:
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92:
77:
75:
68:
64:
61:
58:
56:
52:
46:
43:
40:
36:
31:
19:
1183:Solar radius
1177:Light-second
1176:
1167:
1157:Earth radius
1085:. Retrieved
1081:
1072:
1061:. Retrieved
1057:
1048:
1037:. Retrieved
1033:
1024:
1013:. Retrieved
1009:
1000:
980:
973:
961:the original
947:
936:
932:
929:David Mermin
924:
906:
867:nearest star
748:7 light-days
493:
469:
405:Solar System
402:
366:
360:
309:
246:
174:light-second
173:
171:
59:
54:
38:Unit of
33:Light-second
18:Light minute
805:light-year
745:light-week
621:light-hour
522:Kilometers
508:Definition
421:ephemerides
409:radiometric
280:Julian year
200:travels in
151: units
1280:Categories
1238:gigaparsec
1232:megaparsec
1226:kiloparsec
1214:light-year
1087:2023-03-07
1063:2023-03-07
1039:2023-03-07
1015:2023-03-07
898:References
892:Light-year
858:10 mi
849:10 km
798:Oort cloud
792:10 mi
783:10 km
733:10 mi
724:10 km
686:light-day
671:perihelion
665:10 mi
656:10 km
612:10 mi
603:10 km
562:10 mi
553:10 km
368:Pioneer 10
265:light-year
202:free space
180:useful in
1208:terametre
1196:gigametre
1133:Astronomy
738:Voyager 1
495:Voyager 1
437: s.
397:Mercury's
393:Aldebaran
362:Voyager 1
282:(not the
182:astronomy
1251:See also
1190:☉
1131:used in
939:(2005),
914:Archived
876:See also
514:Example
231: ft
194:distance
145:imperial
133:10
124:10
74:SI units
865:is the
840: m
774: m
715: m
647: m
594: m
544: m
519:Meters
434:385(20)
429:499.004
300:seconds
204:in one
1220:parsec
988:
675:Saturn
525:Miles
399:orbit.
296:
253:length
239:
217:
206:second
163:
115:
89:
55:in ...
42:length
1240:(Gpc)
1234:(Mpc)
1228:(kpc)
964:(PDF)
957:(PDF)
933:phoot
854:5.879
845:9.461
788:1.127
779:1.813
729:1.609
720:2.590
679:orbit
661:6.706
652:1.079
608:1.118
599:1.799
558:1.863
549:2.998
505:Unit
483:Pluto
448:(the
389:Rigel
312:Earth
198:light
196:that
176:is a
110:0.002
1222:(pc)
1216:(ly)
1210:(Tm)
1204:(au)
1198:(Gm)
1179:(ls)
986:ISBN
796:The
669:The
628:3600
446:Moon
365:and
324:foot
249:time
188:and
172:The
112:0040
1166:or
838:800
835:580
832:472
829:730
826:460
817:600
814:557
772:400
769:598
766:478
763:314
761:181
754:800
752:604
713:200
710:371
707:068
704:902
695:400
677:'s
673:of
645:800
642:848
639:252
636:079
592:480
589:547
586:987
542:458
539:792
537:299
457:Sun
431:786
294:400
274:600
271:557
244:).
237:282
235:186
233:or
229:055
226:571
224:983
215:458
212:792
210:299
160:282
158:186
87:458
84:792
82:299
1282::
1164:🜨
1080:.
1056:.
1032:.
1008:.
812:31
810:=
750:=
702:25
693:86
691:=
626:=
584:17
576:=
492:,
302:.
298:SI
292:86
269:31
241:mi
184:,
165:mi
149:US
135:pc
126:ly
117:AU
1192:)
1187:R
1185:(
1173:)
1170:E
1168:R
1161:R
1159:(
1121:e
1114:t
1107:v
1090:.
1066:.
1042:.
1018:.
994:.
968:.
856:×
847:×
824:9
790:×
781:×
731:×
722:×
663:×
654:×
634:1
610:×
601:×
578:1
560:×
551:×
219:m
147:/
131:×
122:×
91:m
20:)
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