Comet ISON: Sky-watchers gear up for rare celestial event

Written by Express news service | Pune | Updated: Oct 1 2013, 19:57pm hrs
Comet isonThe sun-approaching Comet ISON floats against a seemingly infinite backdrop of numerous galaxies. Reuters
Astronomers and amateurs are eying an opportunity to witness a rare celestial event wherein comet ISON will make a passage around the sun in next few weeks. Going by some predictions, the comet will be very bright and have a long tail.

ISON, which belongs to a special category of comets called sungrazers, is expected to become visible to the naked eye in the morning sky an hour before dawn from October-end to January-end of next year.

A national science campaign, Eyes on ISON, has been launched by many organisations, including from Pune, in view of the celestial event.

National Centre for Radio Astrophysics (NCRA), Inter-University Centre for Astronomy and Astrophysics, Navnirmiti, Jyotirvidya Pratishthan, Lokvignyan Sanghatana, Quest, College of Engineering Pune (CoEP), Akashmitra, Vigyan Parisar and Andhashraddha Nirmulan Samiti are some of the local organisations associated with the campaign.

Like all comets, ISON comet is a ball of ice and different gases. It is coming near the sun for the first time. Therefore, its composition is believed to be similar to what it was nearly 4,000 million years ago when the solar system was formed. When the comet comes close to the sun, the ice and gases would start melting, forming a beautiful bright tail running millions of km, said NCRAs Niruj Mohan Ramanujam.

He said ISON is different in character from periodic Halleys Comet that occurs after every 75 years, with the last being spotted in 1986.

As per US space agency National Aeronautics and Space Administration (NASA), ISON will make a sweltering passage around the sun on November 28. The comet will approach within about 1.2 million km of its visible surface, which classifies ISON as a sungrazing comet.

In late November, its icy material will furiously sublimate and release torrents of dust as the surface erodes under the suns fierce heat, all as sun-monitoring satellites look on.

Around this time, the comet may become bright enough to glimpse just by holding up a hand to block the suns glare. Further, following ISONs solar swingby, the comet will depart the sun and move toward earth, appearing in morning twilight through December. The comet will swing past earth on December 26, approaching within 64.2 million km or about 167 times farther than the moon.

As a part of national science campaign, a state-level workshop for selected representatives from scientific community will take place here on Tuesday, followed by public lecture on scientific outlook by scientist Jayant Naralikar at CoEP at 5 pm on Wednesday.

More details and updates on ISON are available on

Photo caption: The sun-approaching Comet ISON floats against a seemingly infinite backdrop of galaxies and a handful of foreground stars in this April 2013 composite image from the Hubble Telescope.

Credit: Reuters/NASA, ESA, and the Hubble Heritage Team (STScI/AURA)/Handout via Reuters