ਬਾਹਰ ਦਾ ਮੰਡਲ ਸੂਰਜ ਤੋਂ ਇੱਕ ਪ੍ਰਕਾਸ਼-ਸਾਲ ਹੈ ਅਤੇ ਅੰਦਰ ਦਾ ਮੰਡਲ ਇੱਕ ਪ੍ਰਕਾਸ਼-ਮਹਿਨਾ। ਇੱਕ ਪ੍ਰਕਾਸ਼ ਸਾਲ (ਚਿੰਨ੍ਹ: ly ) ਲੰਬਾਈ ਮਿਣਨ ਦਾ ਇੱਕ ਸਾਧਨ ਹੈ। ਇੱਕ ਪ੍ਰਕਾਸ਼-ਸਾਲ ਲੱਗ-ਭੱਗ 10 ਅਰਬ ਕਿਲੋਮੀਟਰ ਦੇ ਬਰਾਬਰ ਹੂੰਦਾ ਹੈ। ਇੰਟਰਨੈਸ਼ਨਲ ਐਸਟਰੋਨੋਮੀਕਲ ਯੂਨੀਅਨ ਦੇ ਮੁਤਾਬਕ ਰੋਸ਼ਨੀ ਇੱਕ ਸਾਲ ਵਿੱਚ ਜਿੰਨਾ ਸਫਰ ਤਹਿ ਕਰਦੀ ਹੈ, ਉਸ ਲੰਬਾਈ ਨੂੰ ਇੱਕ ਪ੍ਰਕਾਸ਼-ਸਾਲ ਕਹਿੰਦੇ ਹਨ।[ 1]
Numerical value
ਇੱਕ ਪ੍ਰਕਾਸ਼-ਸਾਲ:
9,460,730,472,580.8 ਕਿਲੋਮੀਟਰ ਹੁੰਦਾ ਹੈ
ਲੱਗ-ਭੱਗ 5,878,630,000,000 ਮੀਲ ਹੁੰਦਾ ਹੈ ਉੱਪਰ ਲਿਖੇ ਅੰਕੜੇ ਜੂਲੀਅਨ ਸਾਲ ਦੇ ਹਿਸਾਬ ਨਾਲ ਹਨ, ਜਿਸ ਵਿੱਚ 365.25 ਦਿਨ ਹੁੰਦੇ ਹਨ।[ 2] [ 3]
List of orders of magnitude for length
Factor (ly)
Value
Item
10−9
40.4×10-9 ly
Reflected sunlight from the Moon 's surface takes 1.2-1.3 seconds to travel the distance to the Earth 's surface. (The surface of the moon is roughly 376300 kilometers from the surface of the Earth, on average. 376300 km ÷ 300000 km/s (roughly the speed of light ) ≈ 1.25 seconds)
10−6
15.8×10-6 ly
One astronomical unit (the distance from the Sun to the Earth ). It takes approximately 499 seconds (8.32 minutes) for light to travel this distance.[ 4]
10−3
3.2×10-3 ly
The most distant space probe , Voyager 1 , was about 14 light-hours away from Earth 9 ਮਾਰਚ 2007 ਤੱਕ [update] [ 5]
100
1.6×100 ly
The Oort cloud is approximately two light-years in diameter. Its inner boundary is speculated to be at 50,000 AU, with its outer edge at 100,000 AU
2.0×100 ly
Maximum extent of the Sun 's gravitational pull (hill sphere /roche sphere , 125,000 AU). Beyond this is true interstellar space
4.22×100 ly
The nearest known star (other than the Sun), Proxima Centauri , is about 4.22 light-years away.[ 6] [ 7]
103
26×103 ly
The center of our galaxy , the Milky Way , is about 8 kiloparsecs away.[ 8] [ 9]
100×103 ly
The Milky Way is about 100,000 light-years across.
106
2.5×106 ly
The Andromeda Galaxy is approximately 2.5 megalight-years away.
3.14×106 ly
The Triangulum Galaxy (M33 ), at 3.14 megalight-years away, is the most distant object visible to the naked eye.
59×106 ly
The nearest large galaxy cluster , the Virgo Cluster , is about 59 megalight-years away.
150×106 - 250×106 ly
The Great Attractor lies at a distance of somewhere between 150 and 250 megalight-years (the latter being the most recent estimate).
109
1.2×109 ly
The Sloan Great Wall (not to be confused with the Great Wall ) has been measured to be approximately one gigalight-year distant.
46.5×109 ly
The comoving distance from the Earth to the edge of the visible universe is about 46.5 gigalight-years in any direction; this is the comoving radius of the observable universe . This is larger than the age of the universe dictated by the cosmic background radiation ; see size of the universe: misconceptions for why this is possible.
↑ "The IAU and astronomical units" . International Astronomical Union. Archived from the original on 2009-10-22. Retrieved 2008-07-05 .↑ "IAU Recommendations concerning Units" . Archived from the original on 2007-02-16. Retrieved 2009-02-23 .↑ Astronomical Constants Archived 2009-03-27 at the Wayback Machine . page K6 of the Astronomical Almanac .↑ IERS Conventions (2003) Archived 2014-04-19 at the Wayback Machine .↑ NASA pressrelease (05-131) 2005-05-24: Voyager Mission Operations Status Report Week Ending March 9, 2007 ↑ NASA : Cosmic Distance Scales - The Nearest Star ↑ Proxima Centauri (Gliese 551) , Encyclopedia of Astrobiology, Astronomy, and Spaceflight ↑ F. Eisenhauer, et al. , "A Geometric Determination of the Distance to the Galactic Center [permanent dead link Astrophysical Journal 597 (2003) L121-L124
↑ McNamara, D. H., et al. , "The Distance to the Galactic Center " (pdf, 298KB), The Publications of the Astronomical Society of the Pacific , 112 (2000), pp. 202–216.
