article image

Hubble takes another look at comet ISON

Charles Black, Founder and CEO of Sen
Oct 19, 2013, 7:00 UTC

Sen—Comet ISON, which is making its way to the inner Solar System for the first time, has been imaged again by the Hubble space telescope.

The latest image, take on October 9, shows the comet intact, despite some predictions it might be disintegrating.

The comet, officially designated C/2012 S1 ISON, will pass within 1.2 million km (730,000 miles) of the Sun on November 28 this year.

The image combines long exposures taken through blue and red filters. Over 29 minutes, Hubble switched back and forth between these filters as it tracked Comet ISON across the sky.

The tail, made of dust particles, appears redder because dust grains reflect redder light. The coma is bluer, as gas sublimates (melts, creating a tail of gas and dust) from the comet's nucleus.

The coma or head surrounding the comet's nucleus appears symmetric, which would probably not be the case if smaller fragments were flying along.

The comet was inside Mars’ orbit and 177 million miles from Earth when pictured by Hubble.

"This new image of ISON clearly shows that the comet is still in good health, with no fragmentation as reported by some observers," explained Nick Howes, Pro-Am Programme Manager of the Faulkes Telescope Project.

"Whatever happens with C/2012 S1 ISON, it's proving to be a very well monitored and observed comet, which, if it does make it past perihelion, could grace our skies nicely, giving us in the Northern Hemisphere the first reasonably good comet, in terms of general public visibility since Hale Bopp in 1997."

Comet ISON

Howes' team are using a range of 2 Metre telescopes as part of an ongoing project studying coma morphology, and imaged the comet very close to the time when Hubble was pointing at it. Image credit: N.Howes/E.Guido/M.Nicolini - Liverpool Telescope La Palma

Howes and his team have been observing and taking science measurements on the dust production rate and inner coma morphology. "It looks like a pretty normal comet, but one that could still pack a few surprises" said Howes.

The comet originated in the Oort cloud, a belt of perhaps a trillion icy bodies beyond the orbit of Neptune in the outer Solar System. Based on its orbit, astronomers believe that this is ISON's first trip to the inner Solar System. It will pass close enough to the Sun to be classified as a sungrazing comet. 

The comet is predicted to make its closest approach to Earth on December 26, coming within 64 million km (40 million miles).

The comet, officially designated C/2012 S1 (ISON), was discovered on September 21, 2012 by Russian astronomers Vitali Nevski and Artyom Novichonok using the International Scientific Optical Network (ISON) telescope.