Speed of Light
Contents
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
