If a star 10 light years away exploded as a supernova, what would be the effect on Earth?

Answer 1

We would be toast. It would be amazingly bright in the sky (much brighter than the Full Moon, but maybe not quite as bright as the Sun), easily visible for months in the daytime sky! (The supernova that created the Crab Nebula, 6000 light-years away, was visible in the daytime for a short time, and was visible at night for a year.)

But we wouldn't be around for months to see it. Any supernova less than around 50 light-years from Earth would destroy life on Earth. The X rays and Gamma rays would kill off a lot of life (lethal doses of radiation). What did survive would likely develop cancer or be rendered sterile. The ultraviolet radiation would destroy Earth's ozone layer within a matter of days. Cosmic rays would arrive a year or two after we see the explosion, also causing damage and death to plants and animals that survived the initial onslaught (if there were any survivors).

Fortunately there aren't any stars that close that will go supernova.

Answer 2

Some supernovas can eject massive amounts of particles from their magnetic poles. So while you might think that the distance would keep us safe, it might not. Remember the pulsars...? They are neutron stars whose magnetic fields only point our way once every so often because the magnetic poles do not line up with the spin axes. They are supposed to be supernova remnants. I would not even like to bet that the prompt radiation would not affect us.

Given that the supernova that formed the Crab Nebula was visible in daylight, and it was much further away (1054 AD or thereabouts) we might not have night for a while. THAT would be a switch!

But if huge amounts of ions were ejected directly at us, we could be irradiated, or our atmosphere could be contaminated. It all depends on how long it would take to get here. They could travel a significant percentage of C, so we might only have a few decades.

Have you spotted anything we should know about...?

Answer 3

It would definitely be bright enough to see in the day time. And I am pretty sure the radiation would be lethal to life on Earth. 10 light years is really close for a supernova.

Answer 4

At maximum power, a supernova is about 10^11 sols worth of total spectral luminosity, and a good bit of that 4E+37 Watts is gamma. Ten light years is 9.5E+16 meters. It would give Earth a gamma flux about 20% as great as the total radiation flux from the sun.

Sounds like we'd all die.

Answer 5

I understand that any supernova less than 30 light years away would spell doom for many Earth species.

At the same time, for those organisms not wiped out, DNA would be affected, creating new species.

Answer 6

We will not anything about it for ten years. Then will see everything on time delay of ten years. Will probably see a very bright star in the night sky for a period of time then some strong telescopes will be able to see the process of the debris flying in the space around it..I Don't believe that even at 10 light yrs distance, short by astronomical measures, still it is way too far to have any effect on our weather or our lives. Would be very interesting to watch and learn.

Answer 7

Ten years later, we would see the explosion. There is a slight possibility it would be a naked-eye phenomenon, but most likely only as a larger, brighter star that would hang out for a few years. The real explosion and its aftermath would remain telescopic objects. No significant radiation other than light would reach the earth, and it would have no effect on us other than as a news story in the "Science" section.

Answer 8

It would be a very bright light in the sky, and the gamma radiation would hit the atmosphere strong enough to screw up satellites.

Answer 9

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Answer 10

The Earth would be hit by a wave of deadly radiation and all life would almost certainly be destroyed.