Boulders balance on tiny tips as comet 67P zooms through space

Three boulders (shown) balance precariously on comet 67P/Churyumov-Gerasimenko in this Sept. 16 image taken 29 kilometers above the surface by the Rosetta spacecraft


Balanced Rock in Arches National Park in Utah has cousins on comet 67P/Churyumov-Gerasimenko. Three boulders — the largest of which is roughly 30 meters across — are barely in contact with the comet’s surface, researchers report May 18 on the Rosetta blog. The resolute rocks showed up in images taken by the Rosetta spacecraft, which has been orbiting comet 67P since August.

Balancing boulders on Earth are either deposited by glaciers or carved by wind and water erosion — none of which exist on a comet. Researchers speculate that the comet’s boulders might have been relocated by surface material slipping and sliding after being heated by the sun. 

Christopher Crockett is an Associate News Editor. He was formerly the astronomy writer from 2014 to 2017, and he has a Ph.D. in astronomy from the University of California, Los Angeles.

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