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Is the moon (still) shrinking?

CORNELL (US)—The highest-resolution images ever taken of the moon have revealed clifflike formations called scarps that suggest the lunar surface shrank within the last 1 billion years—and possibly more recently than that.

Researchers analyzed images captured by NASA’s Lunar Reconnaissance Orbiter (LRO). Details are published in the Aug. 20 issue of Science.

The team based their work in part on 40-year-old images taken during the Apollo missions. But less than 5 percent of the moon’s surface had been photographed under favorable lighting conditions, and evidence of scarps was restricted to the equatorial zone.

The scientists looked at thousands of LRO images, which are sharp enough to resolve the Apollo landing sites and show the scarps in new detail.

The faults show portions of the moon’s crust being thrust over another as a result of the moon cooling and contracting throughout its history.

This observation, says Matthew Pritchard, assistant professor of earth and atmospheric sciences at Cornell University, may tell scientists about the moon’s earthquake and tectonic history.

“So the question is, how many of these faults are there, where are they, and how much have they compressed over time?

That might tell us something about the initial temperatures in the moon,” Pritchard says.

Researchers from Brown University, Johns Hopkins University, Arizona State University, the Smithsonian Institution, the SETI Institute, and the NASA Ames Research Center  contributed to the study, which was supported by the LRO Project and NASA.

More news from Cornell University: www.news.cornell.edu

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