Comet C/2012 S1, more commonly known as ISON, has disintegrated after its close encounter with the sun.
Comets are made up of rocks, dirt, ice and frozen gases and are normally located in the far reaches of our solar system in place called the Oort Cloud. However, it is possible for a comet to be disturbed in its orbit which may cause it to speed towards the sun in a hugely stretched orbit. As it gets closer to the sun, ice in the comet turns to gas. This release of gas and dust produces a bright tail as the comet flies along.
Comet ISON was discovered just over a year ago. At this time, it had already travelled approximately 940 million km since leaving the Oort cloud. Having originated in the Oort Cloud, ISON would swing around the Sun before travelling back out to the edge of our Solar System. Calculations of ISON's path showed that this was the first time the comet made its way towards the inner solar system. The path Comet ISON was following generated a large amount of hype. This was due to the fact that ISON was a type of comet, known as a Sungrazer. These Sungrazing comets pass very close to the sun as they swing around it. These close passes cause the comet to heat up tremendously and release huge quantities of material. This can have one of two effects; the comet can completely disintegrate or it can get a lot brighter than usual. This potential put ISON possibly in line to become the comet of the century.
Despite early predictions of greatness, Comet ISON didn't have a smooth ride. Towards the middle of 2013 it had not brightened as much as expected. This led many to cast doubts on how spectacular this comet would be. These doubts would highlight the skepticism in the scientific community around ISON. If everything was just right, this comet would be a great sight, but there were huge margins for error.
Comet ISON was due to reach perihelion (closest approach to the Sun) on 28 November. As the date approached people were playing close attention to what would happen, various telescopes were pointed towards the Sun to monitor exactly what would occur. NASA's Solar and Heliospheric Observatory (SOHO) was in the perfect position to observe ISON's journey both as it approached and departed the Sun. On the 28th and the days that followed there was much speculation on the fate of ISON but the release of the following video from SOHO and STEREO clearly showed the comet's fate.
Unfortunately ISON's encounter with the Sun was too much for the prehistoric space rock to survive. With temperatures reaching over 2000 degrees celsius the comet's nucleus had been destroyed. Only fragments survived and the hopes that this would be a spectacular viewing opportunity are all but non-existent. While this is disappointing for people who were expecting a fantastic light show it does serve to provide some useful information. First of all, it highlights the complexity and uncertainty when working with orbital mechanics and predicting objects behaviour in space. Another useful application is that this comet has been studied for the best part of a year. We have gained insights into a large portion of its journey. This will help to develop our understanding of the solar system and how comets behave.
There are currently around 5,000 comets being actively tracked and we know this represents a tiny portion of potential cometary objects in our solar system. Hopefully it won't be too long before we have another potentially spectacular comet to watch out for.