Institute for Astronomy to hold comet-viewing event in March

University of Hawaiʻi at Mānoa
Louise H Good, (808) 956-9403
Media Contact, Institute for Astronomy
Roy Gal, (301) 728-8637
Assistant Astronomer, Institute for Astronomy
Posted: Feb 19, 2013

Comet PANSTARRS. Photo by Terry Lovejoy/Austrailia.
Comet PANSTARRS. Photo by Terry Lovejoy/Austrailia.

Comet PANSTARRS C/2011 L4, discovered by the Pan-STARRS 1 telescope on Haleakala in June 2011, is expected to become visible to the naked eye in Hawaiʻi in March.

The Institute for Astronomy at the University of Hawaiʻi at Mānoa will hold a free comet-viewing event on Tuesday, March 12 from 6:30 to 7:30 p.m. at Magic Island’s picnic area 36, which is near the beach at the ewa end. Stargazing will follow comet viewing.

The comet is currently visible in the Southern Hemisphere, but is too far south to be seen here.

From about March 7, it will appear above the horizon in Hawaiʻi. To see it, you will need an unobstructed, cloudless view of the western horizon. It is best to pick a dark spot, away from streetlights. Look in the direction of the sunset just after the sun has gone down. The comet will be just above the horizon. The chart shows the position of the comet in the western sky at 7:00 p.m. throughout the month of March.

The twilight sky will make the comet much harder to see than if it were high up in a dark sky, and moonlight will interfere with viewing the comet after March 13. To see the comet’s tails, you may need a pair of binoculars.

Although the brightness of comets is notoriously difficult to predict ahead of time, scientists expect this comet will have a brightness similar to that of the stars in the bowl of the Big Dipper or Orion’s belt (magnitude 2 to 3).

March 13 may be the best time to take an interesting picture of the comet because on that evening, it will appear just below the thin crescent moon.

By the end of March, the comet will no longer be visible in the evening sky, but if you get up early, you may be able to see it in the eastern sky just before sunrise. However, by then the comet will be farther from both the sun and Earth, and will therefore be fainter.

Comets are balls of ice and dust. As they approach the sun, they heat up, and the ice begins to sublime—to change from ice into a gas. When that happens, they develop a coma, a large envelope of gas and dust that surrounds the solid nucleus, and two tails, a dust tail and an ion tail that consists of gas molecules ionized by sunlight. Each of these tails may be over a million miles long. It is because of the coma and tails that they become visible to the naked eye, sometimes spectacularly so.

Some comets, including Comet PANSTARRS, follow an orbit that begins in the very outer reaches of the solar system. As they pass by the planets, they receive a gravitational “kick” that propels them out of the solar system. Their sole visits to the inner solar system are therefore our only chance to see them.

Others, like Halley’s comet, have elliptical orbits, and return to the inner solar system again and again, although their orbits are sometimes so large that it takes hundreds or thousands of years for them to return.

The Pan-STARRS Project is being led by the University of Hawaiʻi at Mānoa's Institute for Astronomy, and exploits the unique combination of superb observing sites and technical and scientific expertise available in Hawaiʻi. Funding for the development of the observing system has been provided by the United States Air Force Research Laboratory. The PS1 Surveys have been made possible through contributions by the Institute for Astronomy, the University of Hawaiʻi, the Pan-STARRS Project Office, the Max-Planck Society and its participating institutes, the Max Planck Institute for Astronomy, Heidelberg and the Max Planck Institute for Extraterrestrial Physics, Garching, the Johns Hopkins University, Durham University, the University of Edinburgh, the Queen's University Belfast, the Harvard-Smithsonian Center for Astrophysics, the Las Cumbres Observatory Global Telescope Network, Incorporated, the National Central University of Taiwan, and the National Aeronautics and Space Administration under Grant No. NNX08AR22G issued through the Planetary Science Division of the NASA Science Mission Directorate. Any opinions, findings, and conclusions or recommendations expressed in this article are those of the author(s), and do not necessarily reflect the views of the National Aeronautics and Space Administration.


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