Fernandez, University of Central Florida M. Bauer, Jet Propulsion Laboratory/Caltech Y. Weaver, Johns Hopkins University Applied Physics Laboratory J. ISON is managed by the Keldysh Institute of Applied Mathematics, part of the Russian Academy of Sciences. ISON stands for International Scientific Optical Network, a group of observatories in ten countries who have organized to detect, monitor and track objects in space. NASA is bringing to bear a vast fleet of spacecraft, instruments, and space- and Earth-based telescopes to study this rarely seen type of comet over the next year. 28, making it a sungrazer comet that will evaporate its ices and even its rocky dust near perihelion, revealing even more of the comet’s composition. ISON will pass within 724,000 miles of the sun on Nov. With a nucleus less than 2 miles in diameter and weighing between 7 billion and 7 trillion pounds, Comet ISON (officially known as C/2012 S1) is, like all comets, a dirty snowball made up of dust and frozen gases like water, ammonia, methane and carbon dioxide - some of the fundamental building blocks that scientists believe led to the formation of the planets 4.5 billion years ago. In this case, it is most likely created by carbon dioxide that is “fizzing” from the surface of the comet at a rate of about 2.2 million pounds a day. The image on the right side shows the 4.5-micron image with the 3.6-micron image information (dust) removed, and reveals a very different round structure, the first detection of a neutral gas atmosphere surrounding ISON. The 3.6-micron image on the left side shows a tail of fine rocky dust issuing from the comet and blown back by the pressure of sunlight as the comet speeds toward the sun (the tail points away from the sun). The images were taken with SST’s Infrared Array Camera at two different near-infrared wavelengths, 3.6 and 4.5 microns (the false colors shown were selected to enhance visibility). "These data can be used for a broad range of applications, from planning highways and protecting lands with cultural or environmental significance, to searching for natural resources," said Mike Abrams, ASTER science team leader at NASA's Jet Propulsion Laboratory in Pasadena, Calif.These NASA Spitzer Space Telescope (SST) images of C/2012 S1 (Comet ISON) were taken on June 13, when ISON was approximately 310 million miles from the sun. The map is available online to users everywhere at no cost. It features improved spatial resolution, increased horizontal and vertical accuracy, more realistic coverage over water bodies and the ability to identify lakes as small as 0.6 miles (1 kilometer) in diameter. The improved version of the map adds 260,000 additional stereo-pair images to improve coverage. The ASTER data cover 99 percent of Earth's landmass and span from 83 degrees north latitude to 83 degrees south. Image credit: NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team The Advanced Thermal Emission and Reflection Radiometer (ASTER) instrument on NASA's Terra spacecraft provided this spacebird's-eye view of the eastern part of Grand Canyon National Park in northern Arizona in this image, acquired July 14, 2011.
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