Comet ISON, also known as C/2012 S1, has been captured in recent images taken by the Gemini Observatory. This series of images depicts the brightening of the comet of the period of the past couple of months, as it continues racing towards the inner solar system.
Comet ISON is predicted to likely put on quite a show later this year — in late November the comet could possibly become as bright as the Full Moon, and even visible in broad daylight, according to some sources. Of course, comets are notoriously hard to predict, so we’ll have to wait and see with regards to the predictions.
The new sequence of images — documenting the comet from February through May 2013 — shows the rapid brightening of the comet, even while it is still quite a distance from the Sun (455-360 million miles from the Sun). “The information gleaned from the series provides vital clues as to the comet’s overall behavior and potential to present a spectacular show. However, it’s anyone’s guess if the comet has the ‘right stuff’ to survive its extremely close brush with the Sun at the end of November and become an early morning spectacle from Earth in early December 2013.”
Researcher Karen Meech, from the University of Hawaii’s Institute for Astronomy, is now working on a preliminary analysis of the new Gemini data (incorporated with other observations). She notes that the comet’s activity has been decreasing to some degree over the past month or so.
“Early analysis of our models shows that ISON’s brightness through April can be reproduced by outgassing from either carbon monoxide or carbon dioxide. The current decrease may be because this comet is coming close to the Sun for the first time, and a “volatile frosting” of ice may be coming off revealing a less active layer beneath. It is just now getting close enough to the Sun where water will erupt from the nucleus revealing ISON’s inner secrets,” says Meech.
“Comets may not be completely uniform in their makeup and there may be outbursts of activity as fresh material is uncovered,” says astronomer Jacqueline Keane. “Our team, as well as astronomers from around the world, will be anxiously observing the development of this comet into next year, especially if it gets torn asunder, and reveals its icy interior during its exceptionally close passage to the Sun in late November.”
Previous observations have shown that Comet ISON’s main body was releasing somewhere around 850 tons of dust per second towards the beginning of the year. And that ISON’s nucleus is about 3-4 miles in diameter. Researchers have estimated that the comet’s coma is probably about 3100 miles across.
By late October, the comet should be visible through binoculars as a fuzzy glow in the eastern sky before sunrise, in the far southeastern part of the constellation of Leo. By early November, the comet should be a much finer binocular object. It will steadily brighten as it drifts ever faster, night by night, through southern Virgo, passing close to the bright star Spica. It is during the last half of the month that observations will be most important, as the comet edges into Libra and the dawn, where it will brighten to naked-eye visibility and perhaps sport an obvious tail.
The comet reaches perihelion (the closest point in its orbit to the Sun) on November 28th, when it will also attain its maximum brightness, and perhaps be visible in the daytime. If Comet ISON survives perihelion, it will swing around the Sun and appear as both an early morning and early evening object from the Northern Hemisphere. The situation is less favorable from the Southern Hemisphere, as the comet will set before the Sun in the evening and rise with the Sun in the morning.
By December 10th, and given that everything goes well, Comet ISON may be a fine spectacle in the early morning sky as viewed from the Northern Hemisphere. Under dark skies, it may sport a long tail stretching straight up from the eastern horizon, from the constellations of Ophiuchus to Ursa Major. The comet will also be visible in the evening sky during this time but with its tail appearing angled and closer to the horizon.