NASA on Thursday announced that it detected new evidence of water ice on Mercury's poles, detected by its MESSENGER spacecraft, which has been orbiting the planet since 2011. The spacecraft detected relatively large concentrations of ice in impact craters at Mercury's north and south poles, a surprise given the planet is the closest in the Solar System to the Sun (70 million kilometers (44 million miles)* at its furthest point). Here's a NASA diagram of Mercury's south pole showing areas that may contain ice (red):
*Correction: This article originally incorrectly listed Mercury's furtherst distance from the Sun as 44 million miles instead of kilometers. We've since update the article in copy and regret the error.