How close would a su­per­nova have to be to de­stroy life?

All About Space - - Harpercollins -

if a su­per­nova was to go off within about 30 light years of us, that would lead to ma­jor ef­fects on the earth, pos­si­bly mass ex­tinc­tions. x-rays and more en­er­getic gamma rays from the su­per­nova could de­stroy the ozone layer that pro­tects us from so­lar ul­tra­vi­o­let rays. it could also ionise ni­tro­gen and oxy­gen in the at­mos­phere, lead­ing to the for­ma­tion of large amounts of smog-like ni­trous ox­ide in the at­mos­phere.

Su­per­novae hap­pen about once ev­ery 100 years in the Milky Way. But the Milky Way is a big place, roughly 100,000 light years across. Given that, and the fact that the Sun is near the out­skirts of the Milky Way where few stars mas­sive enough to be­come su­per­novae are born, hav­ing a su­per­nova within 30 light years of the Sun should, on av­er­age, hap­pen only once in ev­ery

100 mil­lion years.

the crab neb­ula (M1) is an an­cientsu­per­nova rem­nant

Dr Mark Reid is se­nior ra­dio as­tronomer at the Har­vard-Smithsonian Cen­ter for As­tro­physics

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