Comet PANSTARRS "baby picture", upon initial discovery.
While ISON seems to be getting more of the media headlines, PANSTARRS is actually the one we will get to see first. Originating in a distant region of the solar system called the "Oort Cloud", this comet, like ISON, appears to be making what may be its first every inward sojourn into the inner solar system. This is exciting news for viewers, because this means its condition is pristine and any volatile materials on the surface have not yet been melted or sublimated away. As the comet heats up, potentially for the first time ever, all the ices that are frozen in place will gradually sublimate into space, releasing a tremendous amount of dust in the process. This material produces the fantastic tails that characterize comets. As a comet makes more and more trips through the inner solar system, it is believed that the surface should gradually become tarnished as the ice and loose dust is removed and firmer rock is left behind. Thus, a veteran comet isn't expected to produce much of a show...but a rookie should look fantastic!
There is always the possibility that because this comet hasn't been tested yet, it may be a dud. It could break up as it warms, leaving us with nothing but a debris trail. But let's not think about that.
Instead, here is a diagram from a recent Astronomy magazine I received, predicting the brightness of the comet ("apparent magnitude") and altitude in the sky. The first (yellow) track from January to March is the altitude from the southern hemisphere, while the second (white) track from March to May is the northern visibility. On the magnitude scale, smaller numbers mean that it's brighter.
Visibility track for comet PANSTARS. Copyright: Astronomy magazine.
For us northerners, we are waiting for March when it finally pops up above the horizon. By that point, it will have made its closest approach to the Sun (perihelion) and should look quite bright in the night sky. From our friends in the south, we'll know whether it's living up to expectations or not.
Those of you who have never seen a naked-eye comet before (and that includes me), let's join together for some anticipation. We will look for it at the observatory in the spring at our public observing nights, so even as it fades in brightness in April we should still be able to see it easily in a telescope.
I can only imagine viewing a beautiful bright comet through our 1-meter telescope!
