Speed of Light

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Speed of Light / Lightspeed

Is the distance (299,792,458 metres) that light travels in a vacuum in one second. Light traveling through an object will travel slower than 1 light second.

Exact values and Comparisons (from Wikipedia)

Metres per second 299,792,458 Planck units 1

Approximate values

kilometres per second 300,000

kilometres per hour 1,079 million

miles per second 186,000

miles per hour 671 million

astronomical units per day 173

Approximate light signal travel times

Distance Time

one foot 1.0 ns

one metre 3.3 ns

one kilometre 3.3 μs

one statute mile 5.4 μs

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 parsec 3.26 years

from Proxima Centauri to Earth 4.24 years

from Alpha Centauri to Earth 4.37 years

from the nearest galaxy (the Canis Major Dwarf Galaxy) to Earth 25,000 years

across the Milky Way 100,000 years

from the Andromeda Galaxy to Earth 2.5 million years

from the furthest observed galaxy to Earth 13 billion years

See Also