A duck-shaped comet? You couldn’t planet better

In the year and change since the European Space Agency’s Rosetta mission became the first spacecraft to orbit a comet, the probe has made all sorts of discoveries about the object known as Comet 67P/Churyumov-Gerasimenko-for instance, that it’s bumpy, not smooth as expected, and is covered in dark, carbon-rich compounds with surprisingly little ice.

The August 22, 2014 photo taken by the Navcam of the Rosetta space… But the narrow neck connecting the two lobes has no such features-a sign that the comet didn’t start out as one round, layered object that then gained an unusual shape by spewing material unevenly. “Now, thanks to this detailed study, we can say with certainty that it is a contact binary”.

“These two bodies should have collied very slowly and merged very slowly otherwise we would not have this ordered (onion-like) structure”, team member Matteo Massironi said in a webcast press briefing on Monday. So, the scientists used Rosetta’s images to create a computer model of 67P’s layers, virtually stitching the patches of exposed terracing to visualize how they connected under the surface.

Now scientists think they know how the comet 67P Churyumov-Gerasimenko achieved this shape, claiming that their discovery could give significant insight into how comets and planets may have formed billions of years ago.

ROSETTA-OSIRIS view of 67P/Churyumov-Gerasimenko comet showing the irregular, fractured and stratified morphology of the Seth region of the main body. The layers of each lobe close on each other rather than linking in one continuous set of layers interrupted by erosion. “It must have been a low-speed collision in order to preserve such ordered strata to the depths our data imply”.

“Layering has also been observed on the surface of other comets during previous flyby missions, suggesting that they also underwent a similar formation history”, Davidsson said.

As The Christian Science Monitor’s Pete Spotts wrote in January, comets “are thought to carry some of the most pristine ingredients the young sun and its extended disk of dust and gas had to offer as raw material for planets”.

Comet 67P/Churyumov-Gerasimenko’s quirky double-lobed form left scientists scratching their heads ever since the ancient cosmic traveller first came into the Rosetta spacecraft’s viewfinder a year ago.