Comet ISON is this year’s most anticipated comet. Today (October 1) ISON will sweep closely past the Red Planet Mars. It’ll be on its way to a Thanksgiving Day (November 28) encounter with the sun, and hopefully to a good showing in Earth’s night sky.
Note the greenish color of ISON in Michael’s photo. As it nears the sun, the comet is becoming more active. Jets beginning to spew more vigorously from the comet’s nucleus contain both cyanogen and diatomic carbon, which both glow green when illuminated by strong sunlight.