The great lunar land graben

SMALL PRINT:THE MOON shows signs of recent geological activity, according to a study from Nasa – although recent in this context means tens of million years ago.

Images from the US space agency’s Lunar Reconnaissance Orbiter show small linear valleys or “graben” on the lunar surface that could be a result of the moon’s crust being stretched.

We think the moon is in a general state of global contraction because of cooling of a still hot interior,” said Thomas Watters of the Center for Earth and Planetary Studies at the Smithsonian’s National Air and Space Museum in Washington, on Nasa’s website.

“The graben tell us forces acting to shrink the moon were overcome in places by forces acting to pull it apart. This means the contractional forces shrinking the moon cannot be large, or the small graben might never form.”

The moon is thought to be more than 4.5 billion years old, but the scientist reckon the stretching could have happened relatively recently, less than 50 million years ago, according to the release.

“It was a big surprise when I spotted graben in the far side highlands,” said principal investigator Mark Robinson from Arizona State University. “I immediately targeted the area for high-resolution stereo images so we could create a three-dimensional view of the graben. It’s exciting when you discover something totally unexpected and only about half the lunar surface has been imaged in high resolution. There is much more of the moon to be explored.”