Recently, I was creeped out by this supernova. Detected Feb. 18 by Swift, a satellite launched to look for gamma-ray bursts, the exploding star already was the 24th supernova discovered at that early point in 2006. As instruments improve, exploding stars appear more common than cosmologists had expected, and that's not the best news we might have heard. Coded GRB 060218, this star detonation began as a gamma-ray burst that lasted 33 minutes -- absolutely stunning because previous gamma-ray bursts from space have lasted a few seconds at the most. The gamma rays came from 470 million light-years away. That was discomfiting because strong gamma-ray bursts usually emanate from what astronomers call the "deep field," billions of light-years distant and thus billions of years back in the past. A distance of 470 million light-years means the GRB 060218 supernova happened 470 million years ago. That is ancient by human reckoning, but many cosmologists had been assuming the kind of extremely massive detonations thought to cause strong gamma-ray busts occurred only in the misty eons immediately after the Big Bang. The working assumption was that since life appeared on Earth, there had been no stellar mega-explosion. Now we know there has.
...had GRB 060218 happened in our galaxy, life on Earth would have ended Feb. 18.
Apart from some lithophillic bacteria, perhaps.
470 million LY is not just "not in the furthermost corners of the Universe", it's not that far from the local galactic cluster, which stretches for 10 million LY. Just outside the Virgo Sipercluster in fact. That's the one we're in.
Odds are, conditions within a given Supercluster are fairly uniform, in terms of probablilities of Gamma Ray Bursts like this. A GRB within a Galaxy presses the "reset" button over less than a million years, wiping out all complex life within the whole Galaxy as the Gamma rays propagate outwards.
Puts little problems like Al Qaeda, and trivialities such as minority persecution in perspective, doesn't it?