Comet C/2012 S1 (ISON) is now visible in the morning skies before dawn – and after a little outburst in brightness, many people have reported that it is now just visible to the unaided eye, and should continue to brighten over the next ten days as it approaches its perihelion at just 1 solar diameter from the surface of the Sun.
Here is a video showing you where and when to look for Comet ISON, and discussing how bright it might get.
The temperature at its closest point may exceed 2000K, and the tidal forces on the comet will be very high – both of which mean that there is a chance that Comet ISON’s first visit into the inner solar system might well be its last. If ISON survives, then there’s every chance that it could be visible to most northern hemisphere observers to the unaided eye in the first week or two of December 2013 in both the morning and evening – although morning apparitions will be more favourable.
Comet ISON is not the only comet around at the moment. Comet C/2013 R1 (Lovejoy) is also potentially naked-eye visible in Ursa Major, and the periodic comet 2P/Encke may also approach naked-eye visibility briefly. Both of these comets will also be visible in the same region of sky as ISON at different times – see the video above. There are potentially 2 other comets which are visible in binoculars: Comet C/2012 X1 (LINEAR) brightened unexpectedly by over 100 times in October, and now sits just 1º from the bright star Arcturus, and comet C/2013 V3 (Nevski), discovered only a few days ago, has also experienced an outburst and is around magnitude 9 in Leo.
So fingers crossed that we get to see ISON. The big problem may be the age-old problem for astronomers in the UK… the weather!