april: iron moon
In the last couple of years interest in the Moon has been heightened by the discovery of water ice in some deep polar craters by NASA's Lunar Prospector probe. The technique of conducting geological surveys from orbit was pioneered by the earlier US Department of Defense probe Clementine between February and May 1994. Among its experiments it used cameras capable of detecting a broad spectrum of light, from ultraviolet through visible to infrared, to build a range of mineralogical maps.
This one shows the levels of iron in lunar soils. High concentrations, shown in red and yellow, correspond almost exactly with the lava-filled maria, which are a feature almost exclusively confined to the near side.
Image: Clementine Project.