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Newly discovered comet
due in 2013

by Phil Unsworth
Posted: 20 June 2011

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A new comet has been discovered using telescopes at the University Of Hawaii. Predicted to be visible in the night sky in early 2013, this may be the comet’s only trip into the inner Solar System.

The initial image taken using the Pan-STARRS 1 telescope, with the potential comet shown. Image: Henry Hsieh, University of Hawaii, PS1SC.

The comet, named C/2011 L4 (PANSTARRS), was first detected by the Pan-STARRS 1 telescope from Haleakala, on the Hawaiian island of Maui. Pan-STARRS, the Panoramic Survey Telescope and Rapid Response System, works alongside automated software which scans each new image from the telescope for moving objects. On the night of 5-6 June such an object was found; follow-up observations by University Of Hawaii (UH) astronomer Richard Wainscoat and student Marco Micheli using the Canada-France-Hawaii Telescope at Mauna Kea, Hawaii confirmed the object as a new comet.

The comet is currently 1.2 billion kilometres away from the Sun, between the orbits of Saturn and Jupiter, and too faint to detect with the naked eye. But by 2013 the comet will be at its closest approach to the Sun, approximately 50 million kilometres distant, or roughly the same distance as Mercury, and will be visible low in the western sky after sunset during twilight. How bright the comet will eventually be depends on the comets’ ice content, and how much ice sublimates into gas as it warms up on its approach towards the Sun. Astronomers will study C/2011 L4 (PANSTARRS) over the coming months to improve the predictions.

A composite image of the potential comet, taken using the Canada-France-Hawaii telescope. The object was confirmed as a comet and named C/2011 L4 (PANSTARRS), named for the discovering telescope. Image: Henry Hsieh, University of Hawaii, PS1SC.

C/2011 L4 (PANSTARRS) likely originated from the Oort Cloud, a collection of icy bodies lying in the far outer Solar System, and theorised home of many – if not all – long period comets. Objects in the Oort cloud are only weakly gravitationally bound to the Solar System and so can be disturbed by the pull of nearby stars, sending them on their lengthy journey to the inner Solar System. These comets have periods of hundreds to millions of years, and tend to journey into the inner Solar System, then back out again to either complete a lengthy parabolic orbit, or be flung out of the Solar System altogether.

“C/2011 L4 (PANSTARRS) has an orbit that is close to parabolic, meaning that this may be the first time it will ever come close to the Sun, and that it may never return,” says Wainscoat.

The comet discovery was a bonus to the team’s usual work of scanning the skies for potentially hazardous asteroids – those which may eventually collide with Earth. But there is no cause for concern as the team says that C/2011 L4 (PANSTARRS) will pose no danger to Earth.