Light year is used to measure the distance in space. If you are studying astronomy, it is worth spending some time in getting facts about this interesting unit of measurement.
What is light year?
A light year is a unit of distance. It is the distance that light can travel in a year's time which is six trillion miles. Light moves at a velocity of roughly 300,000 kilometers in every second. So in one year, it can travel roughly about 10 trillion km. One light-year is equivalent to 9,500,000,000,000 kilometers.
Why do astronomers use light year?
Well, it is quite convenient to measure the distances in space using light year. To take just one example, the distance to the next nearest big galaxy, the Andromeda Galaxy, from earth is 21,000,000,000,000,000,000 km. Since it becomes quite difficult to write and interpret this figure using normal units of miles and kilometres, astronomers use light year to interpret it.
The Andromeda Galaxy is 2.3 million light years away. Likewise, The Milky Way Galaxy is about 150,000 light-years across.
Astronomers also use another unit for measuring the distance to other parts of the Milky Way Galaxy. It is known as Parsec and is equal to 3.3 light years.