Skip to main content

Rosetta Spacecraft Spots 'Pyramid' Boulder on Comet (Photos)

'Cheops' Boulder on Comet 67P/Churyumov-Gerasimenko
A close-up of a boulder nicknamed "Cheops," which the Rosetta spacecraft imaged on the surface of comet 67P/Churyumov-Gerasimenko. (Image credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA)

The European Space Agency's Rosetta spacecraft has sent home several spectacular images that show a large pyramid-shaped boulder studding the surface of its target comet.

Rosetta mission team members have named the 82-foot-tall (25 meters) boulder on Comet 67P/Churyumov-Gerasimenko "Cheops," after the largest pyramid in Egypt's famous Giza complex. The rock is much smaller than its namesake, however, which rises 456 feet (139 m) into the Egyptian sky.

Rosetta first photographed Cheops upon arriving in orbit around Comet 67P in early August. Over the past few weeks, the probe has taken close-up pictures and several wide-angle views that highlight the rock and its surrounding boulder field.

"The surface of Cheops seems to be very craggy and irregular," said Holger Sierks, the principal investigator for Rosetta's Optical, Spectroscopic and Infrared Remote Imaging System (OSIRIS), in a statement.

"Especially intriguing are small patches on the boulder's surface displaying the same brightness and texture as the underground," added Sierks, a comet researcher with the Max Planck Institute for Solar System Research in Germany. "It looks almost as if loose dust covering the surface of the comet has settled in the boulder's cracks. But, of course, it is much too early to be sure."

Many properties of Cheops' boulder field are unknown. Scientists are examining what the rocks are made of, how dense they are and how they might have been created. It's possible that as the comet grows more active, the boulders will move around or become more visible to Rosetta's camera, team members said.

Mosaic showing a wide-angle view of comet 67P/Churyumov-Gerasimenko taken from 9.3 miles (15 km) above the surface Oct. 8, 2014. (Image credit: ESA/Rosetta/NAVCAM)

The closest pictures of Cheops were taken from an altitude of about 9.3 miles (15 kilometers), mission officials said. But on Oct. 9, Rosetta moved even closer to the comet to begin an imaging campaign that will take it just 6 miles (10 km) above the surface.

Rosetta, which launched in March 2004, will accompany Comet 67P for at least the next year to see how the icy object changes as it gets closer and closer to the sun.

The mission is the first to successfully place a probe in orbit around a comet, and it will attempt to make some more history next month. On Nov. 12, Rosetta will deploy a small lander called Philae, which will try to make the first-ever soft landing on a comet.

Follow Elizabeth Howell @howellspace, or @Spacedotcom. We're also on Facebook and Google+. Originally published on

Join our Space Forums to keep talking space on the latest missions, night sky and more! And if you have a news tip, correction or comment, let us know at:

Elizabeth Howell
Elizabeth Howell is a contributing writer for who is one of the few Canadian journalists to report regularly on space exploration. She is pursuing a Ph.D. part-time in aerospace sciences (University of North Dakota) after completing an M.Sc. (space studies) at the same institution. She also holds a bachelor of journalism degree from Carleton University. Besides writing, Elizabeth teaches communications at the university and community college level. To see her latest projects, follow Elizabeth on Twitter at @HowellSpace.