| A | B |
|---|---|
| Due to its finite speed, sunlight takes 8 minutes and 10 to 27 seconds to reach Earth, depending on the time of year.1 | … |
| Exact value | … |
| metres per second | 2997924582 |
| Approximate values (to three significant digits) | … |
| kilometres per hour | 1080000000 |
| miles per second | 186000 |
| miles per hour 3 | 671000000 |
| astronomical units per day | 1734 |
| parsecs per year | 0.3075 |
| Approximate light signal travel times | … |
| Distance | Time |
| one foot | 1.0 ns |
| one metre | 3.3 ns |
| from geostationary orbit to Earth | 119 ms |
| the length of Earth’s equator | 134 ms |
| from Moon to Earth | 1.3 s |
| from Sun to Earth (1 AU) | 8.3 min |
| one light-year | 1.0 year |
| one parsec | 3.26 years |
| from the nearest star to Sun (1.3 pc) | 4.2 years |
| from the nearest galaxy to Earth | 70000 years |
| across the Milky Way | 87400 years |
| from the Andromeda Galaxy to Earth | 2.5 million years |
Speed of light
(echo:: @ ᯤ)
Footnotes
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“How long does it take for light from the Sun to reach Earth?”. BBC Sky at Night Magazine. 12 April 2024. Retrieved 25 July 2025. ↩
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“2022 CODATA Value: speed of light in vacuum”. The NIST Reference on Constants, Units, and Uncertainty. NIST. May 2024. Retrieved 18 May 2024. ↩
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Larson, Ron; Hostetler, Robert P. (2007). Elementary and Intermediate Algebra: A Combined Course, Student Support Edition (4th illustrated ed.). Cengage Learning. p. 197. ISBN 978-0-618-75354-3. ↩
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Exact value: (299 792 458 × 86 400/149 597 870 700) AU/day. ↩
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Exact value: (999 992 651 π/10 246 429 500) pc/y. ↩