Sunday, July 20, 2014
Strange Shape to a Comet We are About to Visit
On Wednesday, August 6, the European spacecraft Rosetta is going to have a close encounter of the best kind with a comet (a chunk of cosmic ice mixed with dirt.) It's called Comet 67P (the P stands for periodic comet, meaning it comes around again and again every six and a half years.) Its more informal name is Comet Churyumov–Gerasimenko, after the two astronomers who discovered it on a 1969 photograph.
In mid-July when our photo was taken, the spacecraft was still more than 7000 miles from the comet, but it was already becoming clearer in the camera. And, as you can see, 67P/C-G is weird looking. Instrument project manager project manager Carsten Güttler said,“The images faintly remind me of a rubber ducky with a body and a head."
What could cause the icy body of this comet, which is roughly two and a half miles across, to look like this. One possibility is that it is really two comets stuck together, something we have seen in other comets (such as 8P and 103P). Or maybe it was one comet that broke apart into pieces when it got too close to the gravity pull of a big planet like Jupiter, and this odd fragment is all that's left.
Another possibility is that early in its life the comet got hit by other chunks of cosmic ice or rock, carving out big pieces of it and leaving great rounded valleys behind.
We should learn more when we get closer to this ancient icy visitor, and especially when part of Rosetta attempts a landing. Stay tuned.
In the meantime, here is a great animation of the images from this past week, showing the comet spinning in the majestic darkness of