Posted: Sunday, November 10th 2013 at 8:20am
Comet ISON on track for an earthly visit
By Ken Stanford Staff
DAHLONEGA - Whether it will be a spectacular holiday show or a bust depends on a lot of unknowns, but Earth is getting a heavenly visitor over the next few weeks - one that man nor beast has ever seen.
Comet ISON, which was discovered by two Russian astronomers about a year ago, is on its first journey through our solar system and some scientists - including those at NASA - and others are predicting it to be "a particularly bright and beautiful" comet.
But, Dr. Joe Jones, an associate professor of physics at the University of North Georgia in Dahlonega, isn't so sure. Dr. Jones says there are all kinds of perils facing ISON on its trip through the solar system - the kinds of things that could cause it to break apart.
"The main peril is that tidal forces from the Sun will break the comet apart at its closest approach (perihelion), although many observers are saying the estimated density (of the nucleus) is enough to hold it together," according to Jones. "The intense solar heat from the close pass could also damage the comet nucleus during perihelion."
The comet, which will round the sun on Nov. 28, at a distance of just 730,000 miles from the sun, is what's known as a sungrazing comet, due to its close approach.
ISON - which is believed to have begun its journey at least a million years ago from the Oort cloud, a swath of icy objects that orbit far beyond Neptune - is already visible in north Georgia using strong binoculars and small telescopes but not to the naked eye.
"So if it survives perihelion it should be fairly easily visible through those optical aids during that best viewing period (first week of December) when it will be an early morning object in the east before sunrise, Jones said. "My feeling is you'll hardly be able to see it without a good pair of binoculars."
Dr. Jones says ISON will be nearest Earth around Christmas "but that's not necessarily when it will be brightest." That's when ISON will be just a third of the distance between Earth and the sun, at approximately 28 million miles away, according to NASA.
NASA say if ISON survives its trip around the sun, "there’s a good chance that it will be incredibly bright and easily visible with the naked eye in the Northern Hemisphere." In early December, it will be visible in the morning, low on the horizon to the east-southeast. In late December and early January, it will be visible all night long.
The best case scenario, Dr. Jones says, has it being "much brighter than Venus and you might be able to see it in the daytime." But, he was quick to add "that best case scenario is highly unlikely at this point...as a well-known comet hunter (David H. Levy) once said 'Comets are like cats: they have tails, and they do precisely what they want!'"
Link: A Timeline of Comet ISON's Dangerous Journey
Link: Kuiper Belt & Oort Cloud: Overview
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