The excitement is mounting. We’re going to be talking about comets an awful lot in the coming months. First of all, we have Comet Ison to enjoy. We hope. This mountain of ice and dust has come hurtling in from the outer Solar System and is about to swing around the Sun. At closest approach on 28 November, it will be no more than 1.2 million km (800,000 miles) from our star’s boiling surface.
The big question is: will it survive the encounter? “Sungrazers” like Ison very often just fall apart. But if it can remain intact, this “dirty snowball” will swing back out past the orbits of the inner planets, potentially throwing off huge streams of gas and dust. The comet could appear as a great arc across the sky, no binoculars required. Then again, it might not. Comets are notoriously unreliable. Recent observations have suggested that Ison might fall short of being spectacular, but could still put on a decent show. We won’t know for sure until December.
And come December, we’ll all have started looking forward to the space mission of 2014: Rosetta.
This is the European Space Agency probe that was launched way back in 2004. It’s spent the past nine years working its way out to the orbit of Jupiter, to chase down Comet 67-P/Churyumov-Gerasimenko. The plan is for Rosetta to circle and track this comet as it sweeps in towards the Sun. The big highlight, though, will be the deployment of the probe’s Philae lander. It’s going to try to lock down on 4km-wide 67-P and ride it. How long Philae could withstand any outgassing as the ices heat up on approach to the Sun is anyone’s guess. Will 67-P be a “bucking bronco”? Edited from Rosetta: Riding a ‘bucking bronco’ in space.