Drama Builds For Comet Flyby
By Tom Banse
If you wake up early and the skies are clear, you could be in for a treat this week. A comet named ISON (EYE-sun) should be visible through binoculars over the southeastern horizon. Astronomy websites have hyped the passage of this comet as the best in more than a decade. But a lot depends on a close encounter with the sun next week.
A nice bright comet comes by about once per decade on average says Chris Anderson. He's the observatory coordinator at the College of Southern Idaho in Twin Falls. We're overdue because the last appearance of an easily visible comet around here was Hale-Bopp in 1997. Anderson says Comet ISON shows promise as it dives toward our sun.
Chris Anderson: "Comet ISON is a first time comet. It's never been in the inner solar system before, which means it has a fresh and ready reserve of material to be boiled off."
The gradual vaporizing of the comet is what makes it brighten and develop a nice tail. Anderson suggests slowly scanning with binoculars or even with the naked eye around an hour or 90 minutes before dawn. This week, Comet ISON will be near the star Spica (SPY-kuh) at first and then by Mercury and Saturn low in the east-southeastern sky.
Photo: Comet ISON passed through Virgo earlier this month. Courtesy of NASA/Aaron Kingery.
Chris Anderson: "The comet is going to be morning object for quite a while now. That is because it is moving towards the sun now, but it is going to swing very rapidly around the sun and kind of slingshot right back into the morning sky."
The comet disappears next week when it passes behind the sun. Astronomers are unsure though whether Comet ISON will survive the close encounter. The intense heat and gravitational pull of the sun could break up what is basically "a giant dirty flying snowball."
Chris Anderson: "We're all crossing our fingers that the comet survives the passage. But you know even if it doesn't, that might produce a spectacular show. It just won't last very long. You might get a really great looking comet for a day or so and then it could just disappear as fragments never to be seen again."
If it does survive, Anderson says the comet might be "hard to miss." Our December skies will be graced with a bright fuzzy object with a great streak of a tail sticking up from the horizon.
For more viewing tips, try the helpful graphic in this blog post:
More sky maps and a constantly updated gallery of real-time photos: