Astronomers at the University of Hawaii at Manoa discovered the new comet PANSTARRS in June 2011. Now sky watchers wait to see how bright it will shine, possibly visible to the naked eye this month.
Originally found by the Pan-STARRS 1 telescope on Haleakala, Maui, it was confirmed to be a comet by UH astronomer Richard Wainscoat and graduate student Marco Micheli using the Canada-France-Hawaii Telescope on Mauna Kea.
A preliminary orbit computed by the Minor Planet Center in Cambridge, Mass., shows that the comet will come within about 30 million miles of the sun in March, about the same distance as the planet Mercury. The comet will pose no danger to Earth.
Wainscoat said, “The comet 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.”
PANSTARRS is expected to be visible low in the western sky after sunset, but the bright twilight sky may make it difficult to view.
Wainscoat and UH astronomer Henry Hsieh cautioned that predicting the brightness of comets is notoriously difficult, with numerous past comets failing to reach their expected brightness.
Making brightness predictions for new comets is difficult because astronomers do not know how much ice they contain. Because sublimation of ice (conversion from solid to gas) is the source of cometary activity and a major contributor to a comet’s overall eventual brightness, this means that more accurate brightness predictions will not be possible until the comet becomes more active as it approaches the sun and astronomers get a better idea of how icy it is.
The comet is named C/2011 L4 (or PANSTARRS). Comets are usually named after their discoverers, but in this case, because a large team, including observers, computer scientists, and astronomers, was involved, the comet is named after the telescope.
Comets like PANSTARRS offer astronomers a rare opportunity to look at pristine material left over from the early formation of the solar system.
The comet was found while searching the sky for potentially hazardous asteroids—ones that may someday hit Earth. Software engineer Larry Denneau, with help from Wainscoat and astronomers Robert Jedicke, Mikael Granvik and Tommy Grav, designed software that searches each image taken by the Pan-STARRS 1 telescope for moving objects.
The Pan-STARRS 1 telescope has a 1.8-meter-diameter mirror and the largest digital camera in the world (1.4 billion pixels). Each image is almost three gigabytes in size, and the camera takes an image approximately every 45 seconds. Each night, the telescope images more than 1,000 square degrees of the night sky.
Schedule of Events
- March 4 - 6:07 p.m. EST: Sunset in the Washington, D.C. area.
- March 5 - 5:00 a.m. EST: Comet PANSTARRS makes closest approach to Earth, roughly 102,251,387 miles.
- March 5 - 6:08 p.m. EST: Sunset in the Washington, D.C. area.
- March 7-10: PANSTARRS should become visible through binoculars, and possibly to the unaided eye, somewhere in this time frame. Look very low in the west shortly after sunset.
- March 9 - 11:00 p.m. EST: PANSTARRS reaches perihelion, its closest approach to the Sun, roughly 27,886,742 miles. It is likely to grow a large tail by now. Current predictions put it at magnitude –0.2.
- March 12-18: PANSTARRS is expected to be most prominent this week. It’s immediately left of the very thin crescent Moon on March 12 and well below a more substantial crescent on March 13.
- March 20: – PANSTARRS predicted magnitude 1.3.
- March 28: – PANSTARRS passes within five degrees of the north celestial pole.
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