Comet landslide recorded for first time by Rosetta astronomers (Guardian)
Hannah Devlin Science correspondent
@hannahdev
A landslide on a comet has been documented by astronomers for the first time in images that reveal the dramatic collapse of a 100 metre-long cliff.
The observations by the Rosetta spacecraft of the comet 67P/Churyumov–Gerasimenko, provide before and after snapshots, which show how the dusty avalanche has left a large patch of pristine ice from the comet’s interior exposed.
Astronomers were also able to link the landslide to a cometary outburst that occurred simultaneously in the same location, suggesting that the plumes of dust and gas typically seen as comets come close to the sun are caused by the crumbling and shifting of surface structures such as mounds or cliffs.
Previously, scientists had speculated that outbursts, which at a glance resemble eruptions of geysers on Earth, were the result of blasts of pressurised gas that had built up in the comet’s interior as it warms.
The latest observations suggest an alternative explanation. The images from the Rosetta craft focus on a cliff, known as Aswan, around the “wing” area of the duck-shaped comet 67P. A snapshot from September 2014 shows a giant fracture, 70 metres-long by one metre-wide, along the top of the cliff.
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more: https://www.theguardian.com/science/2017/mar/21/comet-landslide-recorded-first-time-astronomers
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