NASA scientists in Boulder, Colorado have had some surprising return photos from space ship MESSENGER in the past week. The probe has observed a number of "dark halos" in the small Mercury's Caloris Basin.

The Caloris Basin is a big depression on Mercury's surface which is believed to have been formed when a comet or asteroid collided with the planet eons ago. MESSENGER was able to photograph eye-catching dark, glassy formations across the area and others around it.

Scientists aren't sure how these dark rings were formed, but they have two theories as to how the glassy, dark matter manifested. Both hypotheses suggest that the foreign impact from long ago could have a lot to do with it.

First is the possibility that under the Caloris surface is a layer of the unknown material. This could have been uncovered when the asteroid or comet hit Mercury. One fact supporting this is the existence of similar halos in other supposed crash sites outside the Caloris basin.

Another theory tells us that the thermal impact of the comet or asteroid crash on Mercury could have melted rock in the blast area and altered it into its dark, shiny state. Scientists are not discounting this possibility either.

NASA says that if the day comes that astronauts tread Mercury, they may find themselves marching across wide fields of black, glassy shreds. That's certainly something worth looking forward to.