# Stellar Distances

The stars are so far away from us that they appear to be fixed. To measure these large distances we make use of the following units:
1. Light year: A light year is the distance travelled by light at a speed of 3 Ã— 108 m sâ€“1 in one year.

One light year = 9.46 Ã— 1015 m
2. Parsec: A parsec is the distance of a star at which the radius of the earth orbit subtends an angle of one second.

1 Parsec = 3.26 light years
3. Astronomical unit (AU): One astronomical unit is the mean distance of the earth from the sun.

1 AU = 1.496 Ã— 1011 mgo