A group of European researchers found that as comet 67P/Churyumov-Gerasimenko spins its way toward the sun, the ice on its surface thaws and freezes again depending on which part of the rock is exposed to sunlight.
Scientists made the discovery when they analyzed the data beamed back by ESA’s Rosetta probe, which now orbits the fast moving celestial object. Rosetta is the mothership of Philae lander, which is the first man-made object to land on a moving comet. European Space Agency achieved the historical feat on Nov. 12, 2014.
And, since then Rosetta keeps gathering and transmitting troves of data from 67P in its journey toward the sun and back. The latest data show that ice builds up on the comet when that part of it enters shadow, while it reaches again gaseous state when it is exposed to sunlight.
Maria Cristina De Sanctis, an Italian researcher from the Institute for Space Astrophysics and Planetology in Rome, reported that her team saw this cycle reoccurring as the comet spinned several times.
“We were surprised to see so clearly the appearance and disappearance of the ice,”
De Sanctis added.
The recent observations may explain and important aspect of comet life – why some comets do not have any ice on their surface even though they keep releasing water vapors in the empty space. The newly found mechanism may also explain how ice water is brought from the interior of the comet to surface, a process that may even prolong the comet’s life, as one researcher put it.
But the recent discovery does not provide an answer to an older problem that has puzzled scientists ever since the discovery of the comet. They cannot explain 67P’s duck shape. But they do have some theories. Some of scientists believe that Chury was actually two comets who were glued together in a cosmic collision. But the neck of the ‘duck’ or the body’s central region is unusually active, so other researchers believe that this activity helped reshape the comet into its current form.
De Sanctis said that the freeze-thaw cycles observed in the comet’s ice may explain how it got its form. The researchers argued that as the central parts of the comet were exposed to sunlight they lost ice water through gas vapors and gradually shed important mass. This is how the ‘neck’ may have formed.
As a follow-up the research team plans to confirm the theory. On Wednesday, Rosetta moved farther away from the comet’s core in an effort to capture a broader view of the comet.
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