Earthsky.com - 8/24/13
When Comet ISON flies by Mars, it’ll have just crossed the “frost line,” a place outside Mars’ orbit where solar heating is enough to start vaporizing ices on ISON’s surface.
Around the world, astronomers are buzzing with anticipation over the approach of Comet ISON. On Thanksgiving Day 2013, the icy visitor from the outer solar system will skim the sun’s outer atmosphere. Word was that, if it survives its pass near the sun, Comet ISON might emerge as one of the brightest comets in years. Although the prospects for an extremely bright comet are not as good now as they appeared at ISON’s discovery in late 2012, still, astronomers and many others are anticipating this comet.
