July 30, 2013
Comet Of The Century May Be Disappointment Of The Year
Brett Smith for redOrbit.com - Your Universe Online
Once dubbed "the Comet of the Century," Comet ISON may prematurely fizzle out before its much anticipated spectacular debut, according to an analysis from astronomer Ignacio Ferrin, with the University of Antioquia in Colombia.
According to the astronomer's calculations, the comet has not increased in brightness since the middle of January - a somewhat unexpected development given the fact comets tend to get brighter as they approach the heat of the Sun. Comet ISON was expected to eventually become as bright as a full moon and even visible in the daylight.
"Comet ISON has been on a standstill for more than 132 days ... a rather puzzling feat," Ferrin noted in a report recently submitted to the Monthly Notices of the Royal Astronomical Society.
The comet's unusually stable brightness could be explained by a lack of ice or a surface layer of rock that is keeping ice particles from streaming into space.
Another comet, C/2002 O4 Hoenig, exhibited a similar behavior - maintaining the same brightness for 52 days until it finally disintegrated. Comet ISON has been the same brightness for much longer, but astronomers aren't sure of its current status because it has entered the solar glare, making it unobservable.
Named after the International Scientific Optical Network that made its discovery, Comet ISON was first spotted in September 2012 by amateur Russian astronomers. It is currently traveling at a rate of around 16 miles per second and is expected to pass just 730,000 miles from the Sun on November 28.
At that distance, the comet is expected to reach temperatures around 4,900 F - a temperature hot enough to melt lead. The comet will also enter Roche's Limit - where it will be subject to the shearing forces of the Sun's gravity that could ultimately rip it apart.
For those still hoping to catch a glimpse of the comet, scientists expect a brief window of observation between October 7 and November 4. Even during this window it will be difficult to determine the comet's fate, scientists said.
Comet ISON is believed to come from the Oort cloud, a hypothetical spherical cloud of icy rocks that sit almost a light year out from the sun. Some astronomers said Comet ISON is making its first, and potentially last, trip from the cloud to the inner solar system.
According to theory, the objects that make up the cloud were first formed within our solar system, but the gravitational pull of giant planets billions of years ago probably ejected them out to where they are thought to be today.
While direct evidence of the cloud has yet to be found, scientists believe it is responsible for long-period comets, such as Halley's Comet. Passing stars or the gravitational effects of the Milky Way are believed to occasionally dislodge an object and send it hurtling toward the sun. Many of these comets are thought to break apart before they can be seen from Earth.