Strangeness on Mercury...

The MESSENGER spacecraft has been orbiting Mercury, returning wonderful science data about this little-understood member of our solar system.  Early on the science team spotted strange little “hollows” in numerous places all over the planet's surface.  These hollows appear to indicate relatively recent geologic activity, something nobody really expected.  Their appearances is certainly odd: brightly colored (often bluish), and associated with structures that look a bit like Swiss cheese.  As you might imagine, the science team is working hard to understand exactly what these things might be.  Meanwhile, we can enjoy them for their visual interest (and oddity)...