On July 10, 2015, the Rosetta Probe, which had only arrived at the comet in 2014 after an 11 year journey, captured an astounding flash of light on the usually lifeless comet.
Experts had been stumped over an explanation of the phenomenon, with conspiracy theorists believing that alien activity may be to blame.
However, scientists think that they have now solved the mystery.
A mysterious flash of light emerged from Comet 67P
By comparing the edges of a cliff known as Aswan over time on the 4.5 kilometre long comet, experts first noticed a fracture on the cliff’s edge.
But the next time they examined the cliff, the fracture had disappeared and a new edge had come to fruition. They also noted there were several boulders at the bottom of the cliff.
Evidence of the Aswan landslide
The scientists concluded as 11,000 tons of the cliff crumbled, an enormous amount of gas and water ice had been released, which caused the sudden burst of light.
Maurizio Pajola, a researcher at the University of Padua in Italy who was working alongside the European Space Agency (ESA) for their historic mission, said: "The last time we saw the fracture intact was on July 4 and, in the absence of any other outburst events recorded in the following 10-day period, this is the most compelling evidence that we have that the observed outburst was directly linked to the collapse of the cliff.
Comet 67P compared to Paris
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Mon, March 20, 2017
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"If the fractures permeated volatile-rich layers, heat could have been transferred to these deeper layers, causing a loss of deeper ice.
"The gas released by the vaporising material could further widen the fractures, leading to a cumulative effect that eventually led to the cliff collapse."