ISON has flared up as it nears the sun. While some have predicted it will be one of the most visible comets of the century, recent measurements suggest it will be dimmer than expected.
"ISON has dramatically brightened over the past few days. The latest observations put the comet around magnitude 5.7 to 6.1, which is a 2+ magnitude increase from this weekend." Says Carl Hergenrother, Association of Lunar and Planetary Observers
On Nov. 14 astronomers said that the comet had grown 2-3 times brighter than it was around Nov. 10. The human eye can see objects brighter than a magnitude 6.5 (the lower the brighter).
In late Nov. Comet ISON is expected to pass about 684,000 miles from the sun. The result will be a comet that could appear as bright as a full moon, and possibly be visible during the day, too. It will be about 40 million miles away from Earth at its closest point, on Dec. 26.
An image of Comet ISON was captured Oct. 8 from the University of Arizona's SkyCenter, north of Tucson, Ariz. A day later, NASA's Hubble Space Telescope also snapped a picture of the comet when it was about 177 million miles from Earth, confirming an intact nucleus.
Comet ISON passed within 6.5 million miles of Mars the week of Sept. 29, allowing NASA to snap images of the comet from the Mars Reconnaissance Orbiter circling the Red Planet. The brightness of the comet was considerably dimmer than observers had hoped for.
"Based on preliminary analysis of the data, the comet appears to be at the low end of the range of brightness predictions for the observation." says Alan Delamere and Alfred McEwen, NASA HiRISE team
The images were captured with the orbiter's HiRISE camera, which was designed to take pictures of Mars' surface and not comets. Nevertheless, the images match separate recent observations, showing that the comet is much less bright than predicted.
On May 30, the Gemini Observatory in Hawaii released a time-lapse image of Comet ISON taken over 3 months starting in early Feb. Scientists said then that the comet's tail appeared to be diminishing, but that may change as more icy material in the nucleus "is uncovered" as it gets closer to the sun.
In honor of U.S. Independence Day, NASA released a timelapse video of Comet ISON's "fireworks." The five-second video compresses 43 minutes of images taken by Hubble on May 8. During that time, Comet ISON flew 34,000 miles, NASA said.
On April 10, the Hubble Space Telescope captured the first image of Comet ISON, which is traveling at 47,000 miles per hour and was about 386 million miles from the sun (about the same distance as Jupiter) when the picture was taken. The image above was enhanced to better show the comet's nucleus.
Some scientists think Comet ISON's small solid nucleus may disintegrate as it warms when it nears the sun. In Dec. 2011, Comet Lovejoy passed through the sun's atmosphere at a distance of 87,000 miles from its surface. The transit through the super-hot corona gave scientists new data on how magnetic fields operate.
If you would like to view Comet ISON… According to NASA, it is now visible to the naked eye, and can be seen about a half hour before sunrise as a fuzzy green blob in the southeastern skies.
The information in this article is courtesy of Circa