Adrian Jannetta writes
Comets are as unpredictable as cats. It's been clear for many months that 2012 S1 ISON (hereafter, Comet ISON) wasn't going to live up to the initial hype of being as bright as the moon.
After many observations during the past few months things are looking worse for ISON.
The comet is currently just inside the Earth's orbit and is diving towards the Sun for a scorching encounter less than a million km above the solar disk on November 28th. Comet ISON has been getting brighter in recent weeks. It's developed a nice tail and there are lots of images showing it looking healthy.
The problem is that the increased brightness is almost entirely down to the comet being closer to the Sun (and the Earth). ISON is reflecting more sunlight because it is nearer to the Sun and appears brighter also because it is closer to the Earth. The nucleus is not becoming much more active, as we'd hope it would after being heated more. There is ongoing speculation that ISON may break apart in the coming weeks.
I hope ISON proves me wrong, but at the moment it doesn't look like this comet will impress the general public in a few weeks. Whatever happens, astronomers will learn something new about comets like ISON.
Dr Adrian Jannetta FRAS
Amateur astronomer and mathematics teacher. Guitar strumming explorer of the universe!
Proud nerd and founder of the school space club. A young whippersnapper with a bucket-load of passion.