Comet in View in Mid-March

Contact: Rebecca Johnson
Editor, StarDate magazine
512-475-6763; [email protected]


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The best views of comet C/2011 L4, better known as PANSTARRS for the survey that discovered it, will grace the early evening sky by the second week of March, according to the editors of StarDate magazine.

To see the comet, face west around 30 to 40 minutes after sunset beginning around March 10. It will be quite low to the horizon, so a view clear of buildings or trees will be necessary to see it. The comet will be joined in the western sky after dark by the slender crescent Moon on March 12, 13, and 14. Good naked-eye views of the comet should continue for several nights, with the comet remaining visible through binoculars into April.

Discovered in June 2011, PANSTARRS is now making its way toward the Sun from the deepest reaches of the solar system. Its complete orbit takes more than 100,000 years. The comet passed closest to Earth on March 5, but was so low to the horizon after sunset that it was difficult to see. The comet makes its closest approach to the Sun on March 10.

The brightness of comets like PANSTARRS, which have not been seen near Earth before, is notoriously difficult to predict. Astronomers think that this comet may be as bright as first magnitude, meaning about the same brightness as well-known stars like Antares in the constellation Scorpius or Spica in Virgo.

However, some comets break apart as they near the Sun. A comet is essentially a collection of rubble held together by ice. Heat from the Sun causes this ice to vaporize, releasing gasses that can fan out into a tail. Sometimes so much ice vaporizes that that the main body of the comet, the “coma,” completely breaks apart. Should this occur, the comet would quickly dissipate and disappear from view.

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 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 will soon be 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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