(Sen) – One of the most eagerly awaited comets in history is livening up as it heads for its rendezvous with the Sun later this year.
Comet ISON has already been monitored by the Hubble Space Telescope and the Swift satellite as it races in between the orbits of Jupiter and Mars. Now another orbiting observatory, NASA’s Spitzer Space Telescope, has taken its own close-ups.
Images newly released show the comet, officially labelled C/2012 S1, as it appeared with Spitzer’s infrared array camera on 13 June when it lay about 500 million km from the Sun. It was clearly already fizzing with activity.
The picture on the left, taken at a wavelength of 3.6 microns, shows a tail of fine rocky dust being ejected from the comet’s head and being blown away by the pressure of the solar wind.
UK astronomy populariser Stuart Atkinson has setup a blog, Waiting for ISON, with observing advice and star maps to help people view the comet. He told Sen: “These are fascinating observations from Spitzer. We’re all crossing our fingers that this is a good sign and that ISON will become very active as it approaches and rounds the Sun.
“Hopefully it means ISON will captivate us all in early December, but of course everyone should just try and stay calm and not get too carried away. ISON might dazzle and delight us, or disappoint and depress us, it’s too early to say yet, no matter what anyone tells you.
“It’s often said that comets are like cats but I think they’re more like politicians: sometimes they promise us the world at first, to get our attention, and then let us down! But let’s hope for the best!”
The comet has an orbit that is close to a parabola, which suggests it may be on its first journey into the inner Solar System from the Oort cloud of icy bodies that is thought to surround it. It has the consistency of a dirty snowball, being made up of dust and gases such as water, ammonia, methane and carbon dioxide left over from the formation of the planets 4.5 billion years ago.