Green-glowing Comet ISON should survive its trip around the sun

Chances are that Comet ISON is probably not going to live up to the 'Comet of the Century' label it was given after it was first discovered. However, not only is it looking more like it will survive its trip around the Sun, but it's still managing to wow us even now, as this image from early Tuesday morning shows.

The comet first went green a little over a week ago, just as it was approaching the planet Mars. The colour comes from a combination of gases evaporating from the core called cyanogen and diatomic carbon, both of which glow green when they're hit with ultraviolet light from the sun. ISON isn't the first comet to glow green. Comet Lemmon is a good example from earlier this year, and Comet 2009 R1 McNaught turned green a few years ago.

When ISON flew past Mars last Tuesday, the Mars Reconnaissance Orbiter satellite captured pictures of it, and although they were fairly disappointing, those images along with ones from Earth-based telescopes gave an updated view of the comet nucleus. It appears as though the comet is the right size — at least 200 metres wide — to survive its trip around the sun. Also, views from the Hubble Space Telescope showed that the comet is only being heated on one side. Thus, as it gets closer to the sun in late November, it could grow significantly brighter as the cooler side heats up and throws off outbursts of gas.

[ More Geekquinox: King Tut’s jewelry holds evidence of ancient comet impact ]

ISON is visible to telescopes on Earth now, and more and more astronomers — professional and amateur — will be watching the comet as it continues its trek through the inner solar system. It's possible it may become the most observed comet in history, and it is expected to become visible to the naked eye sometime in mid-November. We'll lose sight of it at the end of November, as it dives into the glare of the sun, but in the first days of December it will hopefully emerge to give us a spectacular show well into January.

If you have a telescope and want to see Comet ISON for yourself, your best time to look is in the hours before dawn. Be as far away from light pollution sources as you can, look for red Mars in the eastern sky, just to the right of the constellation Leo, and you should be able to find ISON nearby.

(Image courtesy: Adam Block/Mount Lemmon SkyCenter/University of Arizona)

Geek out with the latest in science and weather.
Follow @ygeekquinox on Twitter!