Comet C/2012 S1 (ISON) continues to slowly brighten in the pre-dawn sky as it picks up speed and moves towards the Sun. Keen northern-hemisphere observers have been imaging the comet and are looking forward to a good apparition in mid-November and through most of December when the comet, if it survives its encounter with the Sun, will be at its brightest. But what are the prospects for seeing the comet from the southern hemisphere?
Through the rest of October and all of November, Comet ISON will follow the ecliptic and pass through the zodiacal constellations Leo, Virgo, and Libra before swinging around the Sun in Scorpius on November 28 (the 29th in Australia and New Zealand). If the comet is on the ecliptic, that means it’s visible in most populated parts of both hemispheres. As the map below shows, Comet ISON will be visible from the latitudes of Australia, New Zealand, and South Africa through all of November until it appears to vanish into the Sun late in the month. As of late October, the comet is too faint to see without a small telescope. It may brighten through November to be easily observable in binoculars or without optical aid.
NOTE: As the comet gets within a few degrees of the Sun at the end of November, all observers must take care not to accidentally look at the Sun with binoculars or a telescope while trying to see the comet.
After the comet reaches perihelion on November 28 and swings around the Sun, that’s the end of the show for deep-southern observers. ISON will only become visible in the northern hemisphere from then onward. In fact in early-to-mid January, the comet will pass through far-northern constellations and pass close to Polaris. Have a look at the detailed map in the Crash Course on Comet ISON.
(Image of Comet ISON at top of page courtesy Terry Hancock and Cliff Spohn).
There is a glimmer of hope for sub-tropical observers in the southern hemisphere. In mid-December, the comet will be just a few degrees above the horizon as seen, for example, from northern Australia. The tail of the comet, if it grows long, may also be visible higher above the horizon from sub-tropical latitudes. But south of that, the head of the comet will not be visible. The map below gives you an idea what to look for on, for example, December 16, 2013 in the east-northeastern sky before dawn from Darwin, Australia.