Thursday, August 16, 2007


Birthday Stars

The stars are so far away from us that their light takes a long time to reach Earth. The closest star apart from the Sun is 4.2 light years away, so its light takes 4.2 years to reach Earth.

Tell the Birthday Stars computer when you were born, and it will look for a star that is your age in light years away from Earth. This means that the light we're seeing from that star today actually left the star around when you were born, and has taken your entire life to reach Earth.


My birthday star is in the constellation Ursa Major.

It has visual magnitude 4.1 meaning that you could see this star with the naked eye in good viewing conditions. It is marked in the center of this star chart.

This star is 52.9 light years away, which means that the light we see from it today set off on its journey at about the same time that you were born. Come back in a month or two and your birthday star may change, as the light from more distant stars reaches Earth.



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