December 2013 - January 2014
If Comet ISON survives its trip around the sun, there’s a good chance that it will be incredibly bright and easily visible with the naked eye in the Northern Hemisphere. In early December, it will be seen in the morning, low on the horizon to the east-southeast. In late December and early January, it will be visible all night long.
A second set of Chandra observations is planned for the middle of December to early January, when ISON will be passing through a transition region in the solar wind, where the hot wind from the Sun's sun's equator is mixed with a cooler wind produced by regions near the poles of the sun.
December 26, 2013
Closest approach to Earth, just a third of the distance between Earth and the sun, at approximately 28 million miles away.