Rosetta spacecraft spots sinkholes on comet 67P

Scientists have found sinkholes or swallow hole on the surface of the comet 67P/Churyumov-Gerasimenko by studying close up images of the comet. These iamges were sent by European Space Agency's Rosetta spacecraft.

The spacecraft first began orbiting the comet in August 2014. Earlier, scientists wondered about these surprisingly deep, almost perfectly circular pits on the comet's surface.

The study reveals that the surface of 67P/Churyumov-Gerasimenko is variable and dynamic, undergoing rapid structural changes as it approaches the sun.

Far from simple balls of ice and dust, comets have their own life cycles.

"These strange, circular pits are just as deep as they are wide. Rosetta can peer right into them," said co-author Dennis Bodewits, assistant research scientist in astronomy at the University of Maryland.

The pits are large, ranging from tens of metres in diameter up to several hundred meters across.

"We propose that they are sinkholes, formed by a surface collapse process very similar to the way sinkholes form here on Earth," Bodewits said.

Sinkholes occur on Earth when subsurface erosion removes a large amount of material beneath the surface, creating a cavern.

The team noted two distinct types of pits: deep ones with steep sides and shallower pits that more closely resemble those seen on other comets, such as 9P/Tempel 1 and 81P/Wild.

The team also observed that jets of gas and dust streamed from the sides of the deep, steep-sided pits -- a phenomenon they did not see in the shallower pits.

The study appeared in the journal Nature.