News in Science

'Comet of the Century' may fizzle out

Stellar fizzer? Astronomers slated to meet this week to discuss observing plans for Comet ISON may not have much to talk about. The so-called 'Comet of the Century' may already have fizzled out.

"The future of comet ISON does not look bright," says astronomer Ignacio Ferrin, with the University of Antioquia in Colombia.

Ferrin's calculations show the comet, which is currently moving toward the Sun at 26 kilometre per second, has not brightened since mid-January. That may be because the comet is already out of ice particles in its body, which melt as the comet moves closer to the Sun, creating a long, bright tail.

Another theory is that the comet is covered in a layer of silicate dust that snuffs out water vapour and other gases that brighten the comet.

"Comet ISON has been on a standstill for more than 132 days ... a rather puzzling feat," writes Ferrin in a paper submitted to the Monthly Notices of the Royal Astronomical Society and posted online at the archival site on the pre-press website arxiv.org.

The comet, named ISON for the International Scientific Optical Network that made its discovery, was found in September 2012 by two amateur Russian astronomers.

It is due to pass about 1.2 million kilometres from the Sun in late November. The relatively close pass was expected to create a massive tail that some scientists predict will be visible even in daylight.

If it survives, that is. At that distance, the comet would reach temperatures of about 2700°C - hot enough to boil lead. It may also be pulled apart by the Sun's gravity.

Scientists believe the comet hails from the Oort Cloud, a cluster of icy rocks that circle the Sun about 50,000 times farther away than Earth's orbit. Calculations show Comet ISON is making its first - and possibly last - voyage into the inner solar system.