How far is a second?

The moon may be 1.3 light-seconds away, but why on earth do we measure distances using time?

minutephysics is now on Google+ - http://bit.ly/qzEwc6
And facebook - http://facebook.com/minutephysics
And twitter - @minutephysics

Minute Physics provides an energetic and entertaining view of old and new problems in physics -- all in a minute!

Music by Nathaniel Schroeder
NEW ALBUM!! -- http://juliansaporiti.bandcamp.com/album/lusitania
youtube: http://bit.ly/pakJLE

Thanks to Ross Diener for contributions and to Perimeter Institute for support. Created by Henry Reich