Will This Be The Comet Of The Century?

NASA’s Deep Impact probe has captured images of Comet C/2012 S1 (ISON), as it moves past the orbital distance of Jupiter on what may be its first trip inwards to the Sun, and possibly a spectacular show.

Comets are notoriously fickle beasts. Chunks of primordial rock, dust, and volatile ices that formed some 4.5 billion years ago around our fledgling sun, they can occasionally fly on Icarus-like orbits that bring them to the inner solar system.

Increasing solar irradiation warms their surfaces and sublimates components like solid water and carbon dioxide – creating great tails of reflecting gas and glowing ions, along with streams of dusty carbon compounds and silicates.

Some of these bodies are on long elliptical orbits that bring them back again and again to the inner solar sanctum. Halley’s comet for example has an approximately 75 year long orbit, and its glowing passage has been recorded by humans some 29 times and probably seen many more.

Others fall inwards from a still mysterious region beyond all known major and minor planets – the Oort cloud. This detritus from our solar system’s youth exists somewhere between about 2,000 and 50,000 times further from the Sun than the Earth is, perhaps even stretching to a light year from us.

It’s these long-period comets (each of which may or may not ever visit us again) that have the greatest potential to light up the brightest as they fall inwards, since they may be essentially pristine, their volatiles ripe for a spot of solar heating.

Comet C/2012 s1, or ISON (International Scientific Optical Network) was discovered in September 2012 by Russian astronomers Vitali Nevski and Artyom Novichonok. It’s an extremely promising candidate for becoming a truly spectacular object both before and after its closest solar approach of 800,000 miles on November 28th 2013.

http://blogs.scientificamerican.com/life-unbounded/2013/02/06/will-this-be-the-comet-of-the-century/