Posted on Mar 21, 2017

    A Cliff Collapsed On A Comet And Scientists Got Photos

    The Rosetta mission might be over, but scientists are still learning new things about comet 67P.

    This is comet 67P, as photographed by the Rosetta spacecraft.

    ESA/Rosetta/NAVCAM, CC BY-SA IGO 3.0

    Or to give it its full name, 67P/Churyumov–Gerasimenko. Comet 67P currently goes round the sun once every six and a half years, travelling at a maximum speed of 135,000 kilometres an hour.

    You may be aware that last year Rosetta crashed into the surface of comet 67P when its mission came to an end. But before it did that, it sent back a ton of data that scientists are still sifting through. And they've just discovered something really neat in some of the photos they got from the mission.

    Here's a close-up photo of a cliff, called Aswan, on comet 67P, taken in September 2014. The arrow is pointing at a fracture on the cliff edge. You can totally guess what happened next.


    The fracture you can see in this picture is 70m long and 1m wide.

    The cliff edge appears to have broken off in a landslide, triggering this outburst you can see in an image from July 2015.

    ESA/Rosetta/NavCam – CC BY-SA IGO 3.0.

    Outbursts like this happen fairly often on comets, and landslides are one of the things that scientists think cause them, but until now nobody has been able to link up an outburst with an actual landslide.

    Here's the cliff on December 2015, a few months after the landslide. The bright spot shows where the cliff edge fractured, leaving a pile of rubble at the bottom of the cliff and exposing the ice underneath.


    This bright spot was first spotted in July 2015, just five days after the outburst, linking the two. A paper out today in the journal Nature Astronomy concludes that these pictures show an "unambiguous link" between the comet's outburst and the cliff collapse.

    A separate paper in the journal Science today says that the landslide and another at a different site happened when the comet was approaching its closest point to the sun, suggesting that sunlight has something to do with it.

    Which means that, even from beyond the grave, Rosetta is teaching us new things about our solar system. 🔭🌚

    Kelly Oakes is science editor for BuzzFeed and is based in London.

    Contact Kelly Oakes at

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