The Comet ISON is all set to enter the solar system and dazzle us later this year. Astronomers say the comet will put up a spectacular display, shining brighter than the moon. Prof S A Mohan Krishna throws light on the ‘Comet of the Century’.
Have you ever seen a comet brighter than the moon? Well, you won’t have to wait too long. Astronomers have discovered a comet 15 times brighter than the moon that will soon be visible to people in India. The ‘Comet ISON’, discovered last year by Russian scientists, will be visible in India towards the end of 2013. Experts say that the comet, which will be seen above the western horizon after sunset, is likely to be visible to the naked eye and could well be brighter than the moon thanks to its positioning.
The comet, named C/2012 S1 (ISON) or more popularly Comet ISON, was discovered by Russian astronomers Vitali Nevski and Artyom Novichonok using the International Scientific Optical Network telescope in September last year.
Experts say it will pass within two million miles of the Sun’s surface later this year, in November, and will fly by the Earth, giving people a chance to witness one of the most spectacular events of the century. They say that the comet will shine 15 times brighter than the moon and potentially be visible in broad daylight! What makes it even more fascinating is that, according to the Russian astronomers, the Comet ISON may be brighter than any comet spotted in the last century and this may end up being its one and only trip to the solar system as its trajectory may see it plunge into the Sun in a fiery death!
At 584 million miles from the Sun, the comet was discovered shining at a magnitude of 18.8 on a scale used by astronomers to gauge the brightness of objects in the sky. This is about 1,00,000 times fainter than what the naked eye can see. For astronomers, the most exciting aspect of this new comet concerns its preliminary orbit, which bears a striking resemblance to that of the “Great Comet of 1680”.
In February 2013, when the comet was still a long way from the Earth, NASA’s Deep Impact Spacecraft took a series of images of the comet. NASA’s twin Solar Terrestrial Relations Observatory spacecraft currently does continuous observations of the Sun from orbit. This should afford the observatories a good view when the comet swings by the Sun in November.
Experts opine that Comet ISON could put on a spectacular show around this time, potentially glowing so brightly that it will be visible in some parts in the daytime.
Astronomers are also excited that Comet ISON’s flyby could give them a rare window into comet composition.
The “dirty snowball” will pass within two million miles of the Sun’s surface making it a ‘Sun-grazing’ comet. It is on a parabolic orbit, which means it probably originated from the outskirts of the solar system, perhaps from the Oort cloud – a mass of icy debris which lies 50,000 times farther from the Sun than the Earth does. It is currently moving inwards from beyond Jupiter and is expected to get as close as 8,00,000 miles (1.2 million km) from the Sun’s surface, providing it survives the Sun’s gravitational forces or radiation. The closest approach will take place on November 28, 2013.
Current predictions are that the object will produce a dazzling display, upto a magnitude of 16 (lesser the magnitude, brighter the object) -- that is far brighter than the full Moon. If predictions hold true, then the Comet ISON will certainly be one of the greatest comets in history, far outshining the unforgettable Comet Hale-Bopp of 1997 and very likely to outdo the Pan-STARRS (C/2011 L4) which stunned people in March this year.
Comet ISON currently resides in the northwestern corner of the constellation Cancer. At magnitude 18, it is too dim to be seen but it will be within the reach of astronomers with CCD cameras in the coming months as it brightens. Observers in the northern hemisphere are highly favoured.
Following its peak brightness in late November, it will remain visible without optical aid until mid-January 2014.
Predictions about a comet’s brightness sometimes exceed their performance. Amateur astronomers of a certain age may remember the hype that surrounded Comet Kohoutek of 1973 that was not quite the “damp squib” it had been portrayed as. It indeed reached naked eye visibility! Even if Comet ISON takes on the same light curve as Kohoutek, it is certain to be spectacular, quite possibly a once-in-a-civilisation’s lifetime event.
Come December 2013 and January 2014, this sun-grazer comet will mesmerise sky gazers and amateur astronomers. For those of you intrigued, don’t forget to catch the “Comet of the Century”.