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Light Year

If we are loo...

Question

If we are looking back in time through telescopes now at stars and galaxies, would it be possible to calculate the distance required away from earth in order to look back and see a moment in history here on earth, theoretically ?

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Solution

An alien who was 5000 light years from earth would see, if
he had a good enough telescope, the earth as it was 5000
years before he was looking.

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