A supernova is a violent event in a star\'s life when it exhausts its fuel, ther

Question

A supernova is a violent event in a star's life when it exhausts its fuel, thermonuclear burning stops, and the star contracts, eventually leading to an explosion that releases enormous amounts of energy. In 1987, a powerful supernova (dubbed, accordingly, "SN 1987a") could be seen with the naked eye at night. The supernova occurred in the outskirts of the Large Magellanic Cloud, a dwarf galaxy "near" to our own galaxy. Assuming a constant distance of about 1.6 times 10^18 km from earth to the supernova, how many years ago did the star actually explode given how long it took the light to reach us?

Explanation / Answer

Time taken for light to reach Earth,

t = (1.6 * 1018 * 103) / (3 * 108) = 5.33 * 1012 s

So, the star exploded 5.33 * 1012 seconds ago.

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