Maurizio Pajola, the astronomer who has been the part of Rosetta since it was launched, was going through few of the images taken by the spacecraft previously, when he discovered something strange.
What Did The Images Reveal?
While going through few of the images, his eyes fell on a picture from December 2015, which showed a bright white patch that shone from the comet's dim surface.
Another image was captured on July 4 by the OSIRIS device showed a bigger gash, which was more than 200 feet long. The gash was noticed around the cliff called Aswan, in the northern part of the comet.
The last image captured by the OSIRIS instrument on July 10 showed a cloud of gas and dust ejecting from the comet. Images from five days later showed that the face of the Aswan cliff had collapsed, thus revealing the materials beneath which caused the landslides.
Landslide On Comet 67P
According to the images, the landslides captured on the Comet 67P/Churyumov-Gerasimenko was a huge lump of ice and a rock, which was supposedly equal to Mount Fuji.
However, the landslide captured by the Rosetta spacecraft is nothing as compared to those which occur on the Earth's surface. The Comet 67P/Churyumov-Gerasimenko, is so small that it has no gravity at all.
Thus, instead of falling down like an avalanche, the materials which fell from the fractured cliff face resulted in an "outburst" of around 22,000 cubic meters of materials. This can almost fill up nine Olympic swimming pools. However, the collapse of the Aswan allowed researchers to get a closer glimpse of what lies inside the comet.
What Led To The Landslide?
According to researchers, during 2015, the cliff was coming very close to the sun. Since then, the Comet 67P has no atmosphere. The part which faces the sun was exposed to huge amounts of heat, which may have led to the eventual landslide.
"This is the time where you get maximum activity, the time where you get maximum amount of change," says Ramy El-Maarry, the lead author on the Science study.
As a result, the Aswan cliff, which is placed in the northern hemisphere of the comet, experiences the coldest temperature of around minus 140-degree Celsius. However, it was due to the small ray of the sun, which slipped through the cliff, that it heated up by 50-degree Celsius, causing the cliff to fracture and ultimately collapse.