The time is drawing near...
It will come within 684,000 miles of the Sun at 18:38 in the evening, the closest distance in its potentially kamikaze quest.
Nasa scientists in America are being given an extra Thanksgiving treat.
Michelle Thaller said: "It's a wonderful holiday roast for all the scientists. While many people will be roasting their turkeys, the sun will be roasting this comet."
If it survives then it will live up to its billing as 'Comet of the Century' and could provide an spectacle so bright it can be seen during the day.
But some are sceptical of the comets chances.
Prof Tim O'Brien, associate director of the UK's Jodrell Bank Observatory told the BBC: "It's like throwing a snowball into fire. It's going to be tough for it to survive.
"But luckily, it's a big object and it moves fast, so it won't spend too much time close to the Sun. There is a lot of uncertainty."
Its not just the heat that poses a threat to ISON. The intense gravitational pull of the Sun could also tear it apart.
In the latest Nasa clip, recorded by STEREO-A, (below) the icy comet can be seen as a bright but tiny object against the licking tendrils of the Sun.
If it does survive then December should be even more of a treat than usual...