On February 23, 1987, a supernova explosion was observed in the Large Magellanic Cloud, 55 kpc distant from us. What year did this star explode?
1. The distance from the Earth to the LMC galaxy is 55,000 pc or (1 pc = 3.26 sv.y) 179300 (~ 180,000) sv. years old
2. This means that the light went from the LMC to the Earth for 180,000 years. This means that the explosion took place 180,000 years ago.
3. It makes no sense to calculate more precisely, since the accuracy with which the distance to the LMC galaxy is given does not exceed 1%
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