Categories: Comets

Comet PANSTARRS Cranks up the Volume

The comet photographed with a 300mm lens. Both the main dust tail and the shorter, fainter Type III dust tail are seen. Credit: Michael Mattiazzo

Brand new photos from amateur astronomers Michael Mattiazzo and Jim Gifford, both of Australia show the current view of Comet C/2011 L4 PANSTARRS down under, and gives sky watchers in the northern hemisphere hope for great views of in little more than a week. The comet has been brightening steadily and now shines around magnitude 2.6, just a little fainter than the stars of the Big Dipper. More images below:

Comet L4 PANSTARRS from Castlemaine, Victoria, Australia on February 28 through an 11-inch telescope. Click for more photos. Credit: Michael Mattiazzo

On February 28, Mattiazzo spotted the comet and a small portion of its dust tail in evening twilight 6 degrees above the western horizon. Using large binoculars he could trace the tail to 1.5 degrees or three lunar diameters. PANSTARRS also has a second fainter dust tail, called a Type III tail, composed of heavier dust particles, dimly visible in the photo below alongside the brighter Type II tail.

Comet L4 PANSTARRS low in the western sky over Bridgetown, Western Australia Feb. 27, 2013. Click for more photos. Details: 400mm lens, 4-second exposure at ISO 5000. Credit: Jim Gifford

A third ion tail, while not currently visible with the naked eye, shows up well in photographs. Dust tails form when the heat of the sun vaporizes dust-laden ices in the comet’s nucleus; solar photons – literally light itself – gently pushes the dust away from the comet’s head into a long, beautiful tail. Gases like carbon monoxide and cyanogen, which are normally neutral, get their energy levels pumped up by the sun’s ultraviolet light, shed their outer electrons and become “ionized.” The same UV light causes the gases to fluoresce a pale blue.

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Additional info: Comet PanSTARRS: How to See it in March 2013

Comets often develop two tails as they near the sun – a curved dust tail and straight, ion tail. Dust tails reflect sunlight and appear yellowish. Ion tails glow blue when comet gases are ionized by UV light from the sun and re-emit it as blue. Credit: NASA

Dust tails generally follow the comet’s curving orbit and assume the shape of a gently-curved arc; ion tails are straight as a stick and point directly away from the sun. Once carbon monoxide molecules have been ionized, they’re susceptible to the magnetic force that flows from the sun as part of the solar wind. The wind with its entrained solar magnetism sweeps by the comet at some 300 miles per second (500 km/sec.) and blows the ion tail straight back exactly opposite the Sun.

With PANSTARRS sprouting tails right and left and peak brightness predictions still around magnitude 1 or 2, get ready for this herald of the new season.

Here’s bascially a naked-eye view of PANSTARRS, taken by Dave Curtis on February 22, 2013 from Dunedin, New Zealand. “The comet was just visible with the naked eye in the twilight,” Dave said. It was taken with a Canon 5D3 and a 70-200mm lens at 70mm:

Comet PanSTARRS on feb. 22, 2013 from Dunedin, New Zealand. Credit: Dave Curtis.

Bob King

I'm a long-time amateur astronomer and member of the American Association of Variable Star Observers (AAVSO). My observing passions include everything from auroras to Z Cam stars. I also write a daily astronomy blog called Astro Bob. My new book, "Wonders of the Night Sky You Must See Before You Die", a bucket list of essential sky sights, will publish in April. It's currently available for pre-order at Amazon and BN.