Eternal Darkness of Petronius Crater
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Eternal Darkness of Petronius Crater

November 2, 2012
Date acquired: September 21, 2012 Image Mission Elapsed Time (MET): 256758110 Image ID: 2625058 Instrument: Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS) WAC filter: 7 (748 nanometers) Center Latitude: 86.82° Center Longitude: 322.3° E Resolution: 84 meters/pixel Scale: Petronius crater is 36 km (22 mi.) in diameter Incidence Angle: 86.8° Emission Angle: 26.3° Phase Angle: 71.1° Of Interest: Near Mercury's north and south pole, the sun is always low on the horizon. Long sunsets and sunrises are broken only by long nights. But for impact craters near the poles, no sunlight ever directly reaches the crater floor due to the long shadows cast by the crater rim. Petronius crater, seen in today's featured image, is one such region of permanent shadow, and is also known to host radar-bright deposits, thought to be water ice. This image was acquired as part of MDIS's north polar imaging campaign. During MESSENGER's primary mission, Mercury's south polar region was repeatedly imaged and areas of permanent shadow were identified. During MESSENGER's extended mission, MDIS will make a dedicated effort to repeatedly image the surface near Mercury's north pole. MESSENGER's highly eccentric orbit, which passes close to Mercury's surface at high northern latitudes, provides an opportunity for particularly high-resolution images of Mercury's north polar region. The MESSENGER spacecraft is the first ever to orbit the planet Mercury, and the spacecraft's seven scientific instruments and radio science investigation are unraveling the history and evolution of the Solar System's innermost planet. Visit the Why Mercury? section of this website to learn more about the key science questions that the MESSENGER mission is addressing. During the one-year primary mission, MESSENGER acquired 88,746 images and extensive other data sets. MESSENGER is now in a yearlong extended mission, during which plans call for the acquisition of more than 80,000 additional images to support MESSENGER's science goals. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

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