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A Tale of Two Comets Encke
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A Tale of Two Comets: Encke

November 26, 2013
Release Date: November 25, 2013 Topics: Stars, WAC Date acquired: 22:56 UTC on November 17, 2013 Instrument: Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS) Of Interest: MESSENGER image of comet 2P/Encke during its closest approach to Mercury. At that time, Encke was approximately 2.3 million miles (3.7 million kilometers) from MESSENGER and 32.7 million miles (52.6 million kilometers) from the Sun. The image is 7° by 4.7° in size and has been slightly smoothed to enhance the faint tail of the comet. The tail was oriented nearly side on to MESSENGER in this image and is seen to stretch several degrees from the comet’s bright coma in the direction away from the Sun. MESSENGER's cameras have been acquiring targeted observations (watch an animation here) of Encke since October 28 and ISON since October 26, although the first faint detections didn't come until early November. During the closest approach of each comet to Mercury, the Mercury Atmospheric and Surface Composition Spectrometer (MASCS) and X-Ray Spectrometer (XRS) instruments also targeted the comets. Observations of ISON conclude on November 26, when the comet passes too close to the Sun, but MESSENGER will continue to monitor Encke with both the imagers and spectrometers through early December. Read this mission news story for more details. 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. During the first two years of orbital operations, MESSENGER acquired over 150,000 images and extensive other data sets. MESSENGER is capable of continuing orbital operations until early 2015. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington/Southwest Research Institute