PANSTARRS’ Long Awaited Debut
With the mid-Atlantic region being covered by winter storm ‘Saturn’ (not a fan of naming winter storms), comet C2011/L4 PANSTARRS is about to make its debut in the northern hemisphere. Observers in the southern hemisphere have been enjoying PANSTARRS for about a month already and it finally brightened enough to be a naked-eye object in the last week or so. While the usual naked-eye threshold is between magnitude +5 and +6 depending on your eyesight and sky conditions, comets aren’t point sources of light like stars and planets and their light is spread out over a larger surface are with respect to the entire sky so their brightness in magnitude can be a little deceiving. Right now PANSTARRS is hovering right around magnitude +2 which puts it theoretically as bright as the brightest stars in Ursa Major, the Big Dipper. For us in the northern hemisphere though, it likely won’t appear as brilliant as it is in the southern hemisphere because of it’s proximity to the sun. The comet is expected to make its northern debut tomorrow, March 7th after sunset. The problem for us is that it is approaching its perihelion, its closest distance to the sun, so it will only be visible during twilight. Picking PANSTARRS out might be difficult and it might only appear to the naked-eye as a small fuzzy ball barely creeping over the western horizon.
That being said, binoculars will be a great aide to those looking to spot PANSTARRS early on. The comet won’t get much higher than 10° above the western horizon. Ten degrees is approximately the size of your clenched fist held at arms length. In order to spot PANSTARRS in its first couple of days in the north you’ll have to find a viewing location that has an unobstructed view of the western horizon that is reasonably dark. Getting away from street lights and house lights is key as they both create a glare that makes it difficult to see and limits your eyes’ ability to adapt to the growing darkness. A rooftop that can be safely accessed might provide a good vantage point to spot the comet.
In a simple pair of 10’x50′ binoculars you should be able to see the dust tail that stretches several degrees beyond the comet’s nucleus. Whether or not an ion tail produced by the solar wind will be visible remains to be seen. As March wears on the comet will steadily rise in the western sky each night as it moves further away from the sun. Again it won’t get very high in the sky but at least towards mid-March you should be able to view it in reasonable darkness until about 7 pm. I’ll be away on a retreat this weekend in a semi-dark region at the top of the Chesapeake Bay so I hope to be able to snap a few pictures of PANSTARRS. I will certainly post anything that is decent.
For now, as winter storm ‘Saturn’ dumps mostly rain on me, I had to settle for this amazing timelapse video of comets Lemmon and PANSTARRS in the sky together. This was taken by Australian astrophotographer and videographer Alex Cheney. It is quite a rare sight to be able to see two comets in the same sky together! I swear those southern hemisphere dwellers get to have all the fun!