COLUMBIA — Tuesday morning could provide the last chance to see Comet ISON before its encounter with the sun.
Comet ISON became visible to the naked eye in areas with favorable viewing conditions late last week after an outburst of activity, but some local astronomers and comet watchers have had a tough time spotting it so far. Tuesday morning's forecast calls for clear skies, though, and it could provide the opportunity to see the comet.
Comet ISON is expected to be visible Tuesday at about 5 a.m. in the southeastern sky, low on the horizon. Right now the comet is at a magnitude of about 5, which is right at the limit of naked eye visibility. It will be near the bright star Spica around 10 degrees above the horizon.
Eric Gustafson, planetarium educator at the James S. McDonnell Planetarium at the Saint Louis Science Center, recommended comet watchers use binoculars and a map of the night sky.
He said viewers won’t need to go too far outside of Columbia to be able to see the comet and added the most important aspect of a viewing spot is a clear view of the eastern horizon since the comet will be low.
ISON is a sun-grazing comet, which, as the term implies, means it will get close to the sun. The comet will be closest to the sun on Nov. 28. After that, it will turn around and head away from the sun.
After Tuesday, the comet will be too close to the sun to be visible again until after it loops around. If ISON remains intact after going around the sun, it will be visible again in the predawn sky around Dec. 5.
But there is no guarantee the comet will survive its dangerous trek. This comet will come so close to the sun that it will penetrate the sun’s atmosphere, where extreme conditions could tear the comet apart.
If Comet ISON does successfully complete the loop around the sun it has the potential to be a spectacular sight.
"This is very rare," said Val Germann, secretary and treasurer of the Central Missouri Astronomical Association. "It could be one of the five brightest comets in the last 100 years."
The last comet of this scale was Comet Hale-Bopp, one of the brightest and most viewed comets of recent history, which was at its peak visibility in 1997.
"It will likely be as bright as Hale-Bopp, maybe even brighter," Germann said. "Comet ISON is on track to be something spectacular like Hale-Bopp — maybe even better."
But comets are very unpredictable, and their status changes often. There is a chance that Comet ISON won’t be as fantastic as many are predicting.
"Comets frequently will not live up to their hype," Gustafson said. "Even to this day, if you ask people to name a comet, they will name Comet Halley. There was so much hype generated about its last pass even though it was a letdown."
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