Swooping over a lunar cold spot

cold spot crater

Cool image time! The oblique image on the right, reduced and cropped to show here, was taken by Lunar Reconnaissance Orbiter (LRO) of an unnamed crater on the Moon’s far side. (Click on the image to see the full picture.) What makes the crater of particular interest is that it during the long 14-day-long lunar night the area around this young crater quickly cools to a temperature about 10 degrees Fahrenheit colder than the surrounding terrain.

Einthoven cold spot crater, the subject of today’s Featured Image, is 1143 m wide, or about the size of Meteor Crater in Arizona. So far, it has no official name — we call it Einthoven cold spot crater because it is just south of Einthoven crater, which is old, degraded, and, at 69 kilometers in diameter, the largest crater in the neighborhood.

Though craters associated with cold spot anomalies are small, the cold spots themselves are often large. The Einthoven cold spot crater anomaly takes in 2070 square kilometers of terrain and extends up to 50 kilometers from the crater. That’s much too large an area for ejecta from the crater to cover, which eliminates the most obvious cold spot formation hypothesis: that material blasted from the crater during its formation could create the cold spot.

So, how to explain the cold spot anomalies? Some researchers invoke a cascading series of tiny secondary impacts traveling outward from the crater-forming asteroid impact, while others believe that gas produced by the impact flows through the top layer of lunar surface material. Either process might “fluff up” the surface, changing the way heat affects it. Few researchers, however, find these explanations to be 100% convincing.

Though the abstract of one science paper proposes using these cold spots as an easy way to quickly identify young lunar craters, the actual cold area of this particular crater does not correspond perfectly to the crater itself. The temperature map at the link shows that the colder region is not even centered on the crater, and has a very irregular shape. Using these mysteriously cold regions on the Moon to identify young impacts I think will be difficult and will have a very large margin of error.