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> Mercury seen by Messenger spacecraft

Mercury seen by Messenger spacecraft

author: Nasa/JHUAPL/ Carnegie Institution of Washington/Novapix

reference: a-mer04-00023

Image Size 300 DPI: 9 * 9 cm

This image was acquired about 56 minutes prior to MESSENGER's closest approach during the mission's recent Mercury flyby, as the spacecraft approached the planet's illuminated crescent. Prominent toward the horizon in this view of newly imaged terrain is a long cliff face. A small impact crater (about 30 kilometers, or 19 miles, in diameter) overlies this lengthy scarp. The scarp extends for over 400 kilometers (250 miles) and likely represents a sign of aging unique to Mercury among the planets in the Solar System. As time passes, the interior of a planet cools. However, the relative size of Mercury's central metallic core is larger than that of the other planets and hence has significantly affected the planet's geologic evolution. The numerous long scarps on Mercury are believed to be the surface expression of faults formed in the rocks of Mercury's crust as the interior of the planet cooled and contracted. This contraction compressed the surface and thrust some sections of crust over others, creating long curving cliffs like the one shown here.

Keywords for this photo:

2008 - ASTRONOMY - BLACK AND WHITE - CLIFF - CRATER - IMPACT CRATER - LIMB - MERCURY - MESSENGER - PLANET -