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Comets, information technology turns out, are rather more agile places than nosotros thought. Comet 67P, where we left Rosetta and Philae not too long ago, is ane such happenin' spot. Scientists poring over photos by Rosetta and Philae accept unearthed prove of a spectacular landslide on 67P — and we defenseless it in action. This is the starting time time anyone has ever caught direct evidence of a landslide on a comet.

The landslide, which took place in July of 2015, would not have looked like any landslide on Globe when it was happening. Comet 67P is so small it has barely whatsoever gravity to speak of. In that surroundings, instead of tumbling downwards like an avalanche, much of the material that broke off from the aging cliff face created an "flare-up." Some 22,000 cubic meters of cloth, enough to fill nine Olympic-size pond pools, floated up above the comet's surface to form a diffuse cloud of dust and gas.

"These images are showing that comets are some of the most geologically active things in the solar system," Pajola said. "We see fractures increasing, dust covering areas that were not dusted earlier, boulders rolling, cliffs collapsing" — all on an object barely wider than the Washington Mall is long.

Here'due south the before and later on:

What makes comets and then active is their lack of atmosphere. With cypher to shield them from the Sun'south directly rays, sometimes the sunlight plays off the landscape in surprising ways. It was wintertime on 67P's northern hemisphere, and winter there is about -160°C. But with 67P positioned how it was, the angle of the sunlight as information technology crested a nearby ridge was such that a focused beam hit the cliffside. Its laser-like intensity raised the local temperature, just there, to 50°C, which was enough of a thermal differential to stress the cliffside until its weakest points only gave out.

Considering the patch exposed past the landslide had such a high albedo — that is, information technology reflected virtually of the lite that struck it — scientists believe the landslide must accept revealed water ice from below 67P'due south surface. After information technology was exposed, the ice sublimated from a solid straight into a gas, and the bright spot faded away. Looking at Comet 67P today, the only inkling that there ever was such a landslide is a piddling pile of rubble at the lesser of the cliff.

Philae was a busy little spacecraft, even though information technology spent its whole tenure on 67P wedged in a crevice. As soon as it landed, scientists started snapping every picture they could get with the lander's cameras, but they just spied it down in its hidey-hole about a month before the end of the mission.

Amidst the things Philae was sent to explore were the geological dynamics and composition of safety-duck-shaped 67P. Scientists have determined that it's likely that comets similar 67P seeded World with organic materials relevant to the formation of life on our planet. Water, though, is another story. Information technology's unlikely that Earth's water came from comets like 67P.