As a Science communicator and one of many insignificant humans – especially in the face of such an ancient object – I find myself extremely excited by the prospect of seeing comet ISON on the Eastern Horizon on the 3rd of December. The last time I was this excited by something in Science it was one our our own acheivements of putting Curiosity on Mars (which I got up very early to watch). This is wonder and grandeur of a more primal nature, free of human interaction, something truly transcendent. It may be something many of us will never see the like of again and so to miss out this time would be a terrible shame. So what is so special about this particular lump hurtling through space?
Comet ISON has come from the Oort cloud which is a large region filled with such relics at the very edge of this solar system. It is believed to have remained in the Oort cloud until it was ejected by the gravity of a neighbouring star. This has led to our star (the Sun) tugging on the comet and pulling it ever closer towards it.
What is so special about this comet is that due to its current trajectory it will pass very close to our Sun indeed. This has earned it the name “sungrazer” as it will pass through the Sun’s corona; the extended outer atmosphere of the Sun. This is a perilous journey for this mass of what is believed to be mostly rock, gas and ice, as the Sun’s rays may obliterate it entirely. This, however, is what will give us our best view of it. As the comet comes into contact with ever increasing ultra violet radiation we can be promised a spectacular view of its tail on its approach. There exist three possible outcomes for ISON at this point as outlined by Dr Matthew Knight from Lowell Observatory in Arizona.
One of the other key features of this event is what we may in fact learn from our encounter with this object. One of the theories that abound as to how water ended up on Earth, and therefore made it agreeable for the development of life, was that comets delivered it here in the form of water ice. There is an abundance of ice throughout the solar system, water ice caps even exist on Mars and the moon Titan contains solid methane which might also be called ice. On our planet though, it is water of a particular type (low deuterium concentration) that is conducive to the development of life; water giving us the medium within which chemicals can mix to become simple amino acids. This event incidently reminds me of a lecture I attended by Lee Cronin about how we make inorganic chemical compounds do more. For an interesting insight into this take a look at the work at Cronin Labs. When the comet passes by scientists hope to analyse the make-up of ISON’s tail to see if there is water vapour there that might indicate the presence of water similar to that on earth. The implications for this would be that if water exists on bodies like ISON that they may indeed have delivered water to us and moreover make the notion that water based life exists elsewhere alot more plausible. Whatever we observe, Comet ISON will surely provide some wonderful insights into the history of our particular planetary neck of the woods.