The Weird Blue “Hollows” on Mercury...

The robotic MESSENGER mission to the planet Mercury has vastly extended our knowledge of that little orb.  One of the oddest things MESSENGER has found are bluish “hollows” dotting the surface, a feature not found so far on any other planet.  The photograph at right (click to enlarge) is on APOD.  You can learn more about the hollows here.

Once again, NASA's little robots are quietly pouring fascinating science data back to Earth – and at a bargain price compared with the relatively useless ISS...