Here are two links about Ison....great stuff!
Here is part of an article found here:
Ison has been traveling for millions of years from the Oort cloud to reach Earth. The comet’s surface is very dark, and it is a few tens of miles across.
Whitehouse says if you jumped into the air while on the surface of the comet, you could leap 20 miles up, and it would take you over a week to come back down.
By the end of the summer next year the comet will become visible in small telescopes and binoculars. A few months later, by October, it will be passing Mars and the surface will shift, with the surface of the rock responding to thermal shock.
As the comet passes the orbit of Earth, the gas and dust geysers will gather force, and the space around Ison will become brilliant as the ice below the surface turns into gas and erupts. Once this happens, it will be reflecting the light of the sun.
By late November next year, the comet will be visible to the unaided eye just after dark in the same direction as the setting Sun. The comet’s tail could stretch like a searchlight into the sky above the horizon.
Ison will then swing rapidly around the Sun, passing within two million miles of it, which is closer than any planet ever does. The comet will be able to be seen to an “unaided eye” for months.
When Ison gets close in its approach to the Sun, it could become intensely bright, but at this point it will be difficult and dangerous to see without special instruments.