Comet ISON on Track for Thanksgiving Roasting, Possible Pre-Dawn Views in Early December
Contact: Rebecca Johnson
Editor, StarDate magazine
512-475-6763; [email protected]
FOR IMMEDIATE RELEASE: November 13, 2013
A comet that’s caused a lot of excitement is racing toward a close encounter with the Sun on Thanksgiving Day, according to the editors of StarDate magazine. Comet ISON will pass about 700,000 miles above the Sun before whipping around and heading back toward deep space — if it survives. If it does, the comet could easily be visible to the unaided eye for a few weeks after the encounter.
An automated asteroid-hunting telescope, part of the International Scientific Optical Network (ISON) in Russia, discovered Comet C/2012 S1 (ISON) on September 21, 2012. Some comet-watchers quickly suggested that it could become as bright as a full Moon late this year. Continued observations, however, show that it’s not brightening as much as those optimistic projections indicated.
However, the comet appears to be holding together as it approaches the Sun, suggesting that it could survive the solar encounter, probably its first.
The comet will get brighter as it approaches the Sun, but more difficult to see through the Sun’s glare. It will shine at its brightest as it passes the Sun, although it will be too close to the Sun to view safely.
Like all comets, ISON is a big ball of frozen gases and water mixed with rock and dust. This ball, the comet’s nucleus, appears to be about three miles wide — large, as comets go. As ISON approaches the Sun, the heat vaporizes some of the comet’s icy surface. That surrounds it with a cloud of gas and dust that can span a hundred thousand miles or more. The Sun pushes some of this material outward to form a glowing tail.
As ISON moves far enough from the Sun for us to see it in early December, it’ll be a pretty sight, with its trail stretching far across the sky, maybe far enough that it could be visible in both evening and morning skies.
ISON will pass closest to Earth on December 26, at a distance of about 40 million miles.
ISON probably came from the Oort Cloud, a vast shell of icy bodies that extends up to one light-year from the Sun. These bodies are leftover “building blocks” from the birth of the solar system, so they contain the same mixture of materials that gave birth to Earth and the other planets. Studying them helps scientists understand how Earth and the other planets took shape.
Published bi-monthly by The University of Texas at Austin McDonald Observatory, StarDate magazine provides readers with skywatching tips, skymaps, beautiful astronomical photos, astronomy news and features, and a 32-page Sky Almanac each January.
Established in 1932, The University of Texas at Austin McDonald Observatory near Fort Davis, Texas, hosts multiple telescopes undertaking a wide range of astronomical research under the darkest night skies of any professional observatory in the continental United States. McDonald is home to the consortium-run Hobby-Eberly Telescope, one of the world’s largest, which is being upgraded to begin the HET Dark Energy Experiment. An internationally known leader in astronomy education and outreach, McDonald Observatory is also pioneering the next generation of astronomical research as a founding partner of the Giant Magellan Telescope.
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