Evaporating Rocks on Mercury
The bright material on the floor of Kertész crater is not the water ice recently confirmed to be in craters near Mercury's poles, but it might well be behaving as ice would on another planet. Mercury's daytime temperatures are so hot at most latitudes that rocks that would be stable at other places in the Solar System may essentially evaporate on Mercury. That is one theory for the formation of these bright, irregular features known as hollows seen here and in many other craters on Mercury.
This image was acquired as a high-resolution targeted observation. Targeted observations are images of a small area on Mercury's surface at resolutions much higher than the 200-meter/pixel morphology base map. It is not possible to cover all of Mercury's surface at this high resolution, but typically several areas of high scientific interest are imaged in this mode each week.
Image: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington [high-resolution]
Caption: Mercury MESSENGER Team