By Greg Bryant
UPDATED 22 September 2011: It’s been 4 years since a bright comet – the Great Comet McNaught of 2007 – graced our skies, and while there have been many fainter ones in the meantime, it’s the bright visitors that really capture our attention. Whenever there’s a potentially bright comet on the horizon, I start counting down in anticipation, something I've done since I began following comets in the mid 1980s.
Now, a just-discovered comet, C/2011 L4 (PANSTARRS), is creating a buzz. There’s a chance that the comet will become visible to the naked-eye in February 2013 for Australian observers.
The comet was first noted on images taken with the 1.8-metre “Pan-STARRS 1” telescope at Haleakala, Hawaii, on the night of 6 June. Follow-up observations with the Canada-France-Hawaii Telescope on Mauna Kea the following night confirmed the cometary nature of the object.
When the comet was announced to the international astronomy community on 8 June, the preliminary orbit gave perihelion on 17 April 2013 at a distance of 0.36 astronomical units from the Sun. Further observations since then have seen the comet's orbit refined to a perihelion date of 10 March 2013 at a distance of 0.30 a.u.
Why is there a buzz? If the comet brightens at a favourable rate, it could become visible to the unaided eye from dark skies in February 2013, deep in the southern sky.
There’s lots of “ifs” here. Just how bright the comet will really turn out to be will depend on how the comet brightens as it nears the warmth of the Sun. Is it a first-time visitor to the inner solar system, or the return of a long-period comet? Knowing that in coming months will give us a little more insight into the likely prospects.
For now, it’s nice to think about the possibilities. We’ll have more information on comet PANSTARRS on this website, on our Facebook page, and in forthcoming issues of Australian Sky & Telescope magazine. With luck, it will be an enjoyable build-up.