So there’s this comet named 168P/Hergenrother. It’s one of a bazillion such iceballs orbiting the Sun, but this one turns out to be more interesting than most. For one thing, it has a short period, orbiting the Sun once every 6.8 years or so. Its orbit goes out to about that of Jupiter’s, and reaches down into the inner solar system about as far as Mars. It never gets closer than about 80 million kilometers (50 million miles) to us, so it’s usually relatively faint, and you need a big ‘scope to observe it.
It was discovered in 1998, and made a second pass down our way in 2005. This year, 2012, it came by again, and folks around the world observed it as they do any comet. But then, in September, it gave us a surprise. A big one. Lots of observers were reporting that practically overnight the comet grew hugely in brightness, getting as much as 700 times brighter than expected! Not only that, but observations showed the shape of the comet had changed, going from fairly point-like to much fuzzier.
That could mean only one thing. The comet was breaking up.