Tuesday, December 28, 2010

Twinkle twinkle little star...

The night sky with plenty of stars is indeed a sight for sore eyes. It feels good to gaze at the quiet night sky but there is more to it than meets the eye. Most of the stars that we see during night wont even exist now!! Can’t believe it? But that’s how it works anyway. The stars that we see are located several light years from earth, meaning that light travelling at 3x10^8 m/s takes several years to reach earth. So technically what we are seeing is the light from stars that have started several years ago. So assume a star which is about 10 light years from earth. Now if that star were to die today we would still see it for another 10 years.

If this is confusing then a simple example would be our Sun. Light takes around 8 minutes to reach earth from the sun. So if the sun suddenly turns off now, we would still see the sun for 8 minutes. So what we see in the sky are the past of the stars. We can look into the past!

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