• Question: How many miles does light travel in a light year??

    Asked by cmacd to David, Paul on 23 Nov 2012.
    • Photo: David McKeown

      David McKeown answered on 23 Nov 2012:

      Light travels about 5878499810000 miles in a year. Which is the same distance Dublin was from Cork before they built the new road.

    • Photo: Paul Higgins

      Paul Higgins answered on 23 Nov 2012:

      Yep, the speed of light is ~300,000 kilometers per second (the distance light travels is its speed times time -> 300,000 times 1 year in seconds…), or 1 foot per nano second. So it takes like 5-10 nanoseconds for light to get to your eyes when you flip a light switch. We see everything in our daily lives as it was a number of nanoseconds ago, and stars as they were years ago.