Rosetta spots balancing rock on Comet 67P

MUNICH, Germany, May 19 (UPI) -- Scientists have spotted a balancing rock among dust and crags of Comet 67P. Researchers spotted the seemingly teetering boulder while analyzing images collected by the Rosetta probe and its OSIRIS camera.

The boulder, which appears to stretch vertically and make minimal contact with the ground, is located on the larger lobe of the snowman-shaped comet 67P/Churyumov-Gerasimenko, in what scientists have dubbed the Aker region.

The balancing rock is the largest of three aligned in an isolated formation. Researchers have estimated it measures roughly 100 feet in diameter.

Like balancing rocks found on Earth (mostly in the Southwest United States and Australia), the boulder stretches vertically and appears as if it could topple over at any moment. The rock looks to be resting on the rim of a small depression, and its center of gravity sits atop only a small point of contact with the ground.

Some balancing rocks on Earth are called "rocking stones," as they can rock back and forth in place without falling over.

"We had noticed this formation already in earlier images," Sebastien Besse, a scientist with the European Space Agency and member of the OSIRIS team, said in a press release. "However, at first the boulders did not seem to differ substantially from other we had seen."

Closeups, however, revealed the stone's more precarious positioning.

Researchers can't be sure how the boulder formed, but they say the comet's journey through space can cause rocks to shift and migrate.

Researchers plan to continue to monitor the rock and its companion, with hopes of getting a better image angle and insight into its nature and origin.