* Astronomy

Hubble Captures Comet ISON

Comet ISON is potentially the "comet of the century" because around the time the comet makes its closest approach to the Sun, on November 28, it may briefly become brighter than the full Moon. Right now the comet is far below naked-eye visibility, and so Hubble was used to snap the view of the approaching comet, which is presently hurtling toward the Sun at approximately 47,000 miles per hour. When the Hubble picture was taken on April 10, the comet was slightly closer than Jupiter's orbit at a distance of 386 million miles from the Sun. Even at that great distance the Sun is warming the comet enough to trigger outgassing from its frozen gases locked up in the solid nucleus. Hubble photographed a jet blasting dust particles off the sunward-facing side of the comet's nucleus. Preliminary measurements from the Hubble images suggest that the nucleus of ISON is no larger than three or four miles across. The comet was discovered in September 2012 by the Russian-led International Scientific Optical Network (ISON) using a 16-inch telescope.
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NASA's Swift Sizes Up Comet ISON

Astronomers from the University of Maryland at College Park (UMCP) and Lowell Observatory have used NASA's Swift satellite to check out comet C/2012 S1 (ISON), which may become one of the most dazzling in decades when it rounds the sun later this year.
Using images acquired over the last two months from Swift's Ultraviolet/Optical Telescope (UVOT), the team has made initial estimates of the comet's water and dust production and used them to infer the size of its icy nucleus.
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NASA's Deep Impact Spacecraft Eyes Comet ISON

NASA's Deep Impact spacecraft has acquired its first images of comet C/2012 S1 (ISON). The images were taken by the spacecraft's Medium-Resolution Imager over a 36-hour period on Jan. 17 and 18, 2013, from a distance of 493 million miles (793 million kilometers). Many scientists anticipate a bright future for comet ISON; the spaceborne conglomeration of dust and ice may put on quite a show as it passes through the inner solar system this fall.
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A sibling for Newton's Comet?

Its orbit resembles that of Kirch's Comet, the Great Comet of 1680, which hangs over Rotterdam in our illustration from a painting by the Dutch artist Lieve Verschuier. After becoming the first comet to be discovered telescopically, this brightened enough to be glimpsed in broad daylight. Sir Isaac Newton was also to demonstrate that the comet's parabolic orbit was perfect harmony with his law of universal gravitation, promulgated only seven year later in his famous work, the Principia. As a consequence, the comet is also known as Newton's Comet.
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