Comet 67P/Churyumov-Gerasimenko, the object now being orbited by the European Space Agency’s Rosetta spacecraft, has a pretty funky shape. “But to better understand how much 67P is representative of the comet-formation process, the exploration of a larger sample of comets is definitively needed”.
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One feature immediately caught scientists and the general public’s eye. In essence, this means the comet is made of two separate cores.
Today, scientists have an answer.
More to the point, comet 67P looks like two onions.
The unusual shape of Comet 67P/Churyumov-Gerasimenko, which the Rosetta spacecraft has been orbiting since previous year, results from a primordial collision of two separate objects in the early solar system, according to scientists who published their findings in the September 28 issue of the journal Nature.
Scientists had been previously unclear as to whether 67P was the result of erosion on one comet or whether they were once two separate objects.
The image below (click for full-size) highlights the patterns that support this finding.
“It is clear from the images that both lobes have an outer envelope of material organised in distinct layers, and we think these extend for several hundred meters below the surface”, said Matteo Massironi, lead author from the University of Padova, Italy.
If those layers were oriented in the same direction-like those of a single onion that had been sculpted to look like a rubber duck-it would be strong evidence for the erosion theory.
“The big news is that the layers of each lobe wrap independently, indicating that the two lobes grew separately and only joined together later in their history, gently “docking” together during an ancient encounter that apparently did little damage to either partner”, Jay Melosh, a professor of planetary science at Purdue University in Indiana who wasn’t involved in the study, told the Associated Press.
It awoke in January previous year, and started its comet approach.
Massironi called these “the first clue that the two lobes are independent”. To test this, the scientists constructed two models.
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“Comets are also known to carry organic compounds”, he added, “and are thought to be one type of vehicle that delivered water and organic chemicals to Earth – chemicals that could serve as building blocks for more complex molecules underpinning organic life”.
