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In the Heart of the Virgo Cluster

Credit & Copyright: Günter Kerschhuber (Gahberg Observatory)

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Thin Skinned and Wrinkled, Mercury is Full of Surprises

A global mosaic of Mercury from MESSENGER.

Until relatively recently, Mercury was one of the most poorly understood planets in the inner solar system. The MESSENGER mission to Mercury, is changing all of the that. New results from the Mercury Laser Altimeter (MLA) and gravity measurements are showing us that the planet closest to our sun is thin skinned and wrinkled, which is very different from what we originally thought.

The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft was launched back in 2004. It took a long time getting to its destination, completing 3 flybys of Mercury before finally entering orbit a little over a year ago. Currently, the spacecraft is in a highly eccentric polar orbit, approaching the planet much closer in the north than in the south. This allows the northern hemisphere to be probed and imaged at enviably high resolutions, but leaves the southern hemisphere poorly understood.

READ HERE

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Enceladus Backlit by Saturn

Image Credit: Cassini Imaging Team, SSI, JPL, ESA, NASA; Color Composite: Gordan Ugarkovic

Explanation: This moon is shining by the light of its planet. Specifically, a large portion of Enceladus pictured above is illuminated primarily by sunlight first reflected from the planet Saturn. The result is that the normally snow-white moon appears in the gold color of Saturn’s cloud tops. As most of the illumination comes from the image left, a labyrinth of ridges throws notable shadows just to the right of the image center, while the kilometer-deep canyon Labtayt Sulci is visible just below. The bright thin crescent on the far right is the only part of Enceladus directly lit by the Sun. The above image was taken last year by the robotic Cassini spacecraft during a close pass by by the enigmatic moon. Inspection of the lower part of this digitally sharpened image reveals plumes of ice crystals thought to originate in a below-surface sea.