How Far Away Are the Stars?
From light-seconds to light-years: understanding the astonishing distances of space.
A light-year measures distance
A light-year is the distance light travels in vacuum in one year, around 9.46 trillion kilometres.
Sunlight takes roughly eight minutes and twenty seconds to reach Earth.
Looking back in time
The farther away a star or galaxy is, the longer its light has travelled. Telescopes show us cosmic history as well as cosmic geography.