Now I don't want to alarm you, but there just happens to be a binary star about 8,000 light years from us that's on the brink of exploding. Not a big deal normally, but this one happens to have its pole pointed right at us, which means that if it explodes in a gamma-ray burst it could shoot a beam of destructive, ozone-layer-melting gamma rays at us all Death-Star-like.
There are enough ifs involved in the situation to make the likelihood pretty slim, but this is definitely one of those situations that astronomers are keeping a careful eye on. It all revolves around WR 104, a humungous star classified as a Wolf Rayet star. Generally, these blow up as a supernova, which is no biggie. But sometimes, they blow up as gamma-ray bursts. What's that mean?
When a very massive star explodes, the inner core collapses, forming a black hole, while the outer layers explode outwards. Due to a complex and fierce collusion of forces in the core, two beams of raw fury can erupt out of the star, mind-numbing in their power. Composed mostly of high-energy gamma rays, they can carry more energy in them than the Sun will put out in its entire lifetime. They are so energetic we can see them clear across the Universe, and having one too close would be bad.
Oh, well at least we will avoid it since it only shoots that energy out the poles, right? Uh, well, actually, its pole seems to be aimed right for us. And what happens if it does hit us?
Models of a GRB exploding at roughly the same distance indicate that the immediate impacts are damage to the ozone layer, and the creation of nitrogen dioxide, which is basically smog. Gamma rays emitted by the burst would hit ozone molecules and shatter them, and models indicate that a GRB at this distance could deplete the ozone layer by 30% globally, with local pockets depleted by 50%. It would take years for the ozone to recover from that. Note that the ozone holes we have been dealing with the past few years are actually depletions of less than 5%. Obviously, this is a big deal.
The good news is that we don't know when this guy is going to explode, be it tomorrow or 20,000 years from now, and we don't know how it'll explode either. Basically, the chances are really slim that anything bad will happen, but I just wanted to add a nice dose of apocalyptic dread to your afternoon. You are welcome! [Bad Astronomy via Neatorama]