Ison: Comet of the Century
Comet Ison came from the Oort Cloud, a mysterious, icy region at the furthest reaches of our Solar System.
It has been hurtling towards the Earth, travelling at more than a million kilometres an hour.
Now it is entering the most perilous stage of its epic journey. It will pass the Sun at a distance of just 1.2 million km, effectively grazing its surface.
It will be getting exposed to more and more intense solar heat, and that will start to sublimate the ices (turning them into gas) at an increasing rate.
The Sun’s intense gravitational field produces tidal forces that will also have a major effect on the comet.
Scientists fear it could follow the path of Comet Lovejoy, which broke apart after it passed near the Sun in 2011. Or it could run out of fuel and fizzle out. It is hoped Ison’s large size could protect it.