Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Me and Galaxy

  1. May 15, 2004 #1
    Would you please tell me how long a starlight can reach my eyes ?
    I have heard that a star might have already gone dead although I can still see it shining bright above...That is correct, right ?
    And another question is as to why I see the star shine with different colors, while it obviously has one only? Or is it just because I may have some problems with my eyes ?

    I made this question just as my curiosity, and admittedly I am ignorant about this, and that there is truely nothing technical at all...

    Thanks for your time and for your answers,

  2. jcsd
  3. May 15, 2004 #2
    Indeed, you can see a star that is already dead. This is because the light it emits travels at a finite speed, and thus uses time to reach your eyes. For example, if a star 20 light-years away suddenly dissapeared, you would still see it shine for 20 years, because the light it emitted just before it died still has to travel for 20 years to reach you.
    As to why you see the star shining in different colors (twinkling), there is nothing wrong with your eyes. This is merely a result of atmosferic disturbances.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook