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• 1 media/1200px-False_Color_View_of_Mercury.jpg 2016-05-09T12:46:04+00:00 Mercury 16 image_header 2016-07-23T11:56:48+00:00 With no real atmosphere and a temperature reaching 427°C on the sunny side, Mercury may not seem like a great spot to look for water.  But on the dark side, facing away from the sun, the temperature of Mercury is a chilly -180°C, so ice would be perfectly stable. The problem however is that Mercury’s rotation (quite odd in itself; 3 Mercury days also equals 2 Mercury years) ensures that eventually the dark side rotates towards the sun and heats up.  And yet there are places on Mercury where we can find ice.  The trick to locating these spots, and it is the same trick that we will use to find ice on our moon, is to find places where the sun never shines.  Near mid-latitudes (e.g. equator), those places don’t exist. But near the poles, close to the spin axis, deep dark holes are locations of eternal shade.  Craters provide such holes and scientists had long suspected, based on Earth-based radar data, that ice might be found there (Check here for an early view of ice on Mercury). Indeed the recent Messenger mission confirmed the existence of water ice in such craters.
  
  If you are interested in more detail, and some images that show the distribution of those icy locations, please read this press release from 2012. In this image from the press release, the locations of ice determined by radar are overlaid on an image of the polar regions of mercury.
  
  
  As the description of the image states:

  All of the larger polar deposits are located on the floors or walls of impact craters. Deposits farther from the pole are seen to be concentrated on the north-facing sides of craters.

  
  The sources of the water on Mercury are the same as the sources of water on all planets.  It is either left over from the initial outgassing during the planet’s formation or deposited on the surface later during bombardment.