Pictures taken July 20 of comet 67P/Churyumov-Gerasimenko by the Rosetta spacecraft show cool new stuff. They include several tantalizing depressions in both lobes of the comet and a bright collar where the two dissimilar halves meet.
What makes the comet’s ‘neck’ bright might help us understand how 67P/C-G got its strange shape. It could be a region of freshly exposed ice, differences in the composition of the material where the two lobes meet or a change in elevation in the landscape. More detailed studies including examination with a spectrograph to nail down its composition will have to wait until August 6th and beyond, when Rosetta parks itself in orbit.
Look closely and you’ll also see several depressions. One of the largest is a shallow bowl at the top of the smaller lobe. No one knows if these are impact craters or some kind of collapse pits created where ice below the surface vaporized away during the comet’s regular swings past the sun every 6.5 years.
More and more observations of the 67P/C-G are being made every day. Everything from determining its mass and volume, which will be used to arrive at the comet’s density, to measuring the rate at which gas and dust boils off the icy nucleus.
The animation above covers one full 12.4 hour rotation of the nucleus. The next batch of pictures is expected on July 31 with the first high resolution images arriving on August 6.