Astronomers measure the distance of stars using a constant speed standard. This is the speed of light in empty space.
Speed of light 299,792,458 meters per second (186,000 miles per second)
Wow! Think how fast that is!
One light year is the distance that light travels in one year. 1 Light year is equal to about 10 trillion kilometers or 6 trillion miles!
The Sun is about 8 light minutes away. The next closest star to us is Alpha Centauri which is 4.2 light years away.
Our galaxy, The Milky way is about 100,000 light years across!
Question How many kilometres is Alpha Centauri from us? Why is it a lot easier to use light years?
Arny, Thomas T. (2006) Explorations: An Introduction to Astronomy, Fourth Edition , The McGraw-Hill Companies, Inc. pp9, ISBN 0-07-302580-1.
Arny, Thomas T. (2006) Explorations: An Introduction to Astronomy, Fourth Edition , The McGraw-Hill Companies, Inc. pp10, ISBN 0-07-302580-1.