Video Reveals How Ice Could Exist on Mercury — PICTURES

Shown in red are areas of Mercury’s north polar region that are in shadow in all images acquired by the Messenger spacecraft to date. The polar deposits imaged by Earth-based radar are in yellow. (NASA/Johns Hopkins University/Carnegie Institution of Washington/National Astronomy and Ionosphere Center)

Mercury forms a beautiful crescent shape in this image, acquired as the Messenger spacecraft was high above Mercury's southern hemisphere on May 24, 2011. (NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington)

This image shows an area of Mercury’s surface taken from an altitude of 280 miles above the planet during the Messenger spacecraft’s first orbit with the camera in operation in 2011. (NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington)

The bright rays of Hokusai crater can be seen crossing the surface of Mercury from north to south. This color image also highlights some of the subtle color variations observed on the planet. (NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington)

As NASA’s Messenger spacecraft drew closer to Mercury for its historic first flyby, the spacecraft acquired this image in 2011 showing a variety of surface textures, including smooth plains at the center of the image, numerous impact craters, and rough material that appears to have been ejected from the large crater to the lower right. (NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington)

An unnamed basin, largely filled with smooth plains, occupies most of this image from Messenger. (NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington)

The largest crater in this scene, located in the upper left portion of the image, is Belinskij, named for the Russian literary critic and journalist Vissarion Grigoryevich Belinskij (1811-1848). (NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington)

This 2011 image is shown in a polar stereographic projection, with the south pole at the center, 0° longitude at the top, and 90° E longitude to the right. (NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington)

This 2011 image shows March crater, named for the 15th century Valencian poet Ausiàs March. (NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington)

This image shows a close-up of an unnamed crater on Mercury in 2011. (NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington)

At a diameter of 62 miles, the crater Atget is one of the largest within the Caloris basin of Mercury. (NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington)