February 6, 2013
Massive Comet To Put On Spectacular Show This Thanksgiving
Alan McStravick for redOrbit.com - Your Universe Online
Kislovodsk, literally translated, means “sour water.” It was in this town, named for the sour water in the springs that surround it, that Russian astronomers Vitali Nevksi and Artyom Novichonok made a very sweet discovery in September of last year.
Officially, the comet they discovered was named C/2012 S1, but since the two astronomers were using the International Scientific Optical Network´s (ISON) 15.7-inch reflecting telescope, the common name for their celestial find is simply Comet ISON.
This new comet might not be so new, however. As experts have noted, the trajectory of its preliminary orbit is only too similar to the “Great Comet of 1680.” Conjecture abounds regarding the possibility that Comet ISON may be a direct descendant of the Great Comet or even the very same object that put on a dazzling display over three centuries ago as it paid a visit to our corner of the cosmos.
For a group of scientists at the University of Maryland, however, one thing is certain: This comet has star appeal. For this reason, they have decided make a movie of Comet ISON using NASA´s historic Deep Impact spacecraft, which began tracking and studying it only recently.
And this comet´s star is not fading. Evidence points to the expectation of a bright future. On this year´s Thanksgiving Day, the researchers say that the comet will put on an exciting celestial show that should be visible from many points all over the globe. As it approaches our Sun, sky watchers can expect to see the comet and its 40,000-mile-long tail in both the dark night and as well as by daylight. And this will not just be a one-night event. Comet ISON will be visible for almost a full two months.
"This appears to be this comet's first ever journey into the inner solar system and it is expected to pass much closer to the sun than most comets — within a distance of only a few solar radii," says Maryland astronomer Tony Farnham of the Deep Impact science team. "Thus it offers us a novel opportunity to see how the dust and gas frozen in this comet since the dawn of our Solar System will change and evolve as it is strongly heated during its first passage close to the Sun."
A SPECTACULAR CELESTIAL SHOW
As Comet ISON makes its closest approach to the sun, astronomers say that viewers can expect to see a rapid whirling of the comet as it engages in a near hairpin-like turn around the sun. At this point, they predict that the comet will become dazzlingly bright, rivaling the brightness of a full moon, as it streaks across our sky.
Working with Farnham are fellow team members Ken Klaasen of NASAs Jet Propulsion Laboratory and Michael A´Hearn of the University of Maryland´s Deep Impact Principal Investigator. Along with other colleagues, the team says this comet was discovered far earlier than most comets that decide to take a tour through our inner solar system.
“We see sun grazers [comets that pass close to the sun] all the time, but most are only seen as they flare up very close to the sun. With this comet, we are able to study it from where it is currently, farther from the sun than Jupiter and about five times farther from the sun than Earth, until its closest approach to the Sun, called its perihelion, on November 28th.”
Researchers say that Comet ISON´s coma and tail, also known as its ℠entourage,´ have already started to form. The entourage consists of dust and gas that will continue to grow both in size and its reflected brilliance as Comet ISON moves ever closer to our Sun. Peak luminance will occur as the comet approaches its first solar close-up. This peak is expected to be exceptionally dramatic.
That is, of course, if Comet ISON doesn´t break up after cruising so close to the intense heat of our home star. If it survives this close encounter with the Sun, however, the experts say that it will put on an even brighter display as it departs.
"This is the fourth comet on which we have performed science observations and the farthest point from Earth from which we've tried to transmit data on a comet," said Tim Larson, project manager for the Deep Impact spacecraft at NASA's Jet Propulsion Laboratory in Pasadena, Calif.
Previous Deep Impact studies have performed close flybys on two other comets. The first flyby, on July 4, 2005, allowed the team to crash a probe craft onto Tempel 1. This first probe received world-wide attention and led to an unprecedented advance in comet science. Additionally, Deep Impact has performed scientific observations on two other comets, Garradd and now Comet ISON.
The research team has begun an imaging campaign for Comet ISON. The campaign is expected to yield infrared data, light curves and visible-light images. Looking for the curvature of light around the comet helps the researchers to determine its rotation rate. The movie of the comet was generated in this initial data collection campaign. Though the comet is still traveling through our outer solar system some 474 million miles from the sun, it has already become very active. The most recent reading collected last month showed that the tail of Comet ISON was already over 40,000 miles long.
As ISON will not pass any closer to Earth than 40 million miles on December 26 of this year, researchers have been quick to point out that the this comet poses absolutely no threat to Earth.
Comets are made up of varying amounts of dust and ice particles, leading many scientists to refer to them as “dirty snowballs.” The ice is comprised of both frozen gases and sometimes water. As comets near the Sun, the warmth helps to melt the “dirty snowball” and allows them to shed much of their frozen gas and dust in a process known as sublimation. It is this burning off of dust and gas that reflects sunlight and gives the comet its radiance as it passes by the sun.
In addition to the turkey, stuffing, mashed potatoes and fruit salad, Comet ISON promises to offer a spectacular treat this Thanksgiving for both seasoned astronomers and novice skygazers alike.