Postition of C/2012 S1 ISON (comet ISON) during late 2013. Starfield by Stellarium.
Comet ISON made it's closest approach to the sun on November 28. It did not survive the encounter intact and the remains appear to be dissipating, growing dimmer as they follow the orbit of the original comet. It seems that nothing will be visible to the naked eye, hopes of a spectacular show on December mornings have been dashed. However the break up is yielding valuable scientific data on the origins of the solar system. More, and an animation of the comet's turn round the sun, at the Sky and Telescope.
The picture shows the predicted position of comet Ison during October, November and December 2013. Only the position is shown and there is no intention to show the brightness relative to the starfield. The actual brightness, like all new comets, is very unpredicatable.
The comet grazes the sun at a distance of 1.17 million km on November 28. It may then be very bright and visible in the daytime. However being so close in the sky to the sun it will be hard to locate and dangerous to view without the correct equipment.
If comet Ison survives the close solar encounter it will pull northwards away from the sun and fade. It should be visible in the evenings and mornings, before sunrise will still be best. It's tail will point northwards away from the sun during the night. The comet could break up into several pieces as happened to comet Lovejoy 2 years ago.
October 18: Conjunction with Mars.
November 28: Perihelion (closest approach to the sun, 1.17 million km)
December 26: Closest approach to earth (64.2 million km)