For several millennia, celestial objects have captured the imagination of professional and amateur astronomers. Through the end of the year, newly designated comet, ISON, will appear in the skies.
According to Dr. Jay Pasachoff, professor of astronomy at Williams College, amateur enthusiasts first saw ISON, in 2012, and that spirit runs through the entire field, even among scholars. He said such sightings generate much excitement, especially in the United States.
"Comet ISON was discovered by Russian amateur astronomers who run what they call the International Scientific Optical Network, or ISON," Pasachoff said. "It's fun to see a Great Comet with its tail arcing across the sky. I remember seeing Comet Hale-Bopp that way in 1997, and I took a great picture of it by merely putting my camera on a tripod across the street from my house. There's a bright comet like that every 10 years or so, though not always visible to us in the northern hemisphere."
Astronomers nationwide are tuned into already visible ISON's trajectory. Rebecca Johnson, editor of StarDate magazine and spokesperson for the McDonald Observatory, University of Texas at Austin, said ISON is racing toward a close encounter with the sun, and will reach its closest point to the sun, also known as its perihelion, on Thanksgiving Day.
"Comet ISON will pass about 700,000 miles above the Sun before whipping around and heading back toward deep space, if it survives," Johnson said from her Austin office. "If it does, the comet could easily be visible to the unaided eye for a few weeks after the encounter."
Some comet-watchers, Johnson said, suggested ISON could become as bright as a full moon late this year. Continued observations, however, show it's not brightening as much as those optimistic projections indicated.
Still, Johnson added the comet appears to be holding together as it approaches the sun, suggesting it could survive the solar encounter.
"As ISON moves far enough from the sun for us to see it in morning twilight in early December, it'll be a pretty sight," Johnson said. "ISON will pass closest to Earth on Dec. 26, at a distance of about 40 million miles."
For those who want to see it, scholars and amateur observers are stressing safety first. Dr. Steven Souza, observatory supervisor at Williams College, said care is of paramount importance while ISON is near the sun.
"If Comet ISON does get bright enough to be really interesting, no special equipment will be needed, just a willingness to get up well before dawn and find a spot from which you can see a clear horizon in the general direction of the coming sunrise," Souza said. "Be careful, however! Attempting to observe Comet ISON near perihelion poses some risk to your eyesight if you fail to block out the sun from your field of view."
Souza explained this is true even for those watching with the naked eye, but is especially dangerous for anyone using binoculars or a telescope and to accidentally point them -- even for an instant -- at the sun.
Kevin Collins, president of the Amherst Area Amateur Astronomers Association, echoed Souza's advice. He said observing ISON closer to sunrise as it rises later in the morning requires experience and guidance.
"This will be a danger to observers with unprotected eyes, and it isn't recommended that inexperienced observers attempt to find ISON with binoculars or telescope without proper guidance from an experienced observer," Collins said. "Even if the sun hasn't reached horizon, this happens very quickly and unexpectedly. If looking through binoculars or a telescope trying to find the comet, it could prove disastrous. We highly recommend that the public contact local astronomy clubs for comet observing times and safe guidance."
While Pasachoff also stressed safety, he returned to the theme of pure excitement and whimsy, channeling history and literature in a way that makes Comet ISON much like a visit from a new friend.
"Comets have long known to be spectacular, and the off-Broadway production of ‘Natasha, Pierre, and the Comet of 1812' is a musical play that my wife and I recommend," Pasachoff said. "Based on ‘War and Peace,' it uses the apparition of the Great Comet of 1811, which remained visible to the eye for seven months, as a key plot element. Comet ISON may not quite match that Great Comet, but it can be spectacular on its own terms."