|image source: wired.co.uk|
A light year is a unit of distance. A light-year is how astronomers measure distance in space. Astronomers measure the distance to the Andromeda galaxy using light-years. One light-year equals about 6 trillion miles. This galaxy is over 2 million light-years from Earth. If you could travel at the speed of light, you could circle the globe of Earth almost eight times in one second.