Comet C/ISON details emerge as it races toward the Sun

Oct 11, 2013
This image shows the color change of Comet C/ISON's dust coma. The white dot at the center of the coma marks the location of the nucleus. ISON's dust coma appears to be less red near the nucleus than it is further away from the nucleus. Although the color change is actually very small, it could be an indication of relatively more water ice particles near the nucleus. Those icy particles evaporate, as they move outward, makes the coma appear redder. Credit: NASA, ESA, J.-Y. Li (Planetary Science Institute) and Hubble Comet ISON Imaging Science Team

Scientists are unraveling more information on Comet C/2012 S1 (ISON) as it continues on its journey toward the Sun. Comet C/ISON will skim 730,000 miles above the Sun's surface on Nov. 28 and has the potential to be readily visible from Earth starting in early December.

"We measured the rotational pole of the nucleus. The pole indicates that only one side of the is being heated by the Sun on its way in until approximately one week before it reaches it closest point to the Sun," said Planetary Science Institute Research Scientist Jian-Yang Li, who led a team that imaged the comet.

"Since the surface on the dark side of the comet should still retain a large fraction of very volatile materials, the sudden exposure to the strong sunlight when it gets closer to the Sun than Mercury could trigger huge outbursts of material," Li said.

Li presented the findings today at the American Astronomical Society's Division for Planetary Sciences 45th Annual Meeting in Denver.

Comet C/ISON was imaged with the Hubble Space Telescope using the Wide Field Camera 3 on April 10.

"We measured the color of the coma, and found that the outer part of the coma is slightly redder than the inner part," Li said. "This color change is unusual in comets, and seems to imply that the inner part contains some water ice grains, which sublimate as they move away from the nucleus."

Comet C/ISON was imaged with the Hubble Space Telescope on April 10 using the Wide Field Camera 3, when the comet was 394 million miles from Earth. Credit: NASA, ESA, J.-Y. Li (Planetary Science Institute) and Hubble Comet ISON Imaging Science Team

Comet C/ISON was discovered in September 2012 when it was farther away from the Sun than Jupiter, and was already active at such a great distance. This is distinct from most other sungrazers – comets that pass extremely close to the – that are only discovered and remain visible for at most several days when nearest the Sun. At such a close perihelion distance from the Sun, sungrazers are expected to be intensely heated by the Sun, and sublimate not only ice but also silicates and even metals, releasing a tremendous amount of dust. The expectation is high that Comet C/ISON will be much brighter and more spectacular than most other sungrazers when it puts on a show late this year.

"As a first-time visitor to the inner solar system, Comet C/ISON provides astronomers a rare opportunity to study a fresh comet preserved since the formation of the Solar System," Li said. "The expected high brightness of the comet as it nears the Sun allows for many important measurements that are impossible for most other fresh comets."

Explore further: Video gives astronaut's-eye view inside NASA's Orion spacecraft

Related Stories

Preparing for comet ISON

Sep 24, 2013

(Phys.org) —ESA's space missions are getting ready to observe an icy visitor to the inner Solar System: Comet ISON, which might also be visible in the night sky later this year as a naked eye object.

Hubble brings faraway comet into view

Apr 23, 2013

(Phys.org) —The NASA Hubble Space Telescope has given astronomers their clearest view yet of Comet ISON, a newly-discovered sun grazer comet that may light up the sky later this year, or come so close to ...

A new view of comet ISON

May 03, 2013

Here's a new image of Comet C/2012 S1 ISON, as seen on May 1, 2013 by Ernesto Guido and Nick Howes of the Remanzacco Observatory. They used the 2 meter La Palma Telescope. Their initial approximation of the ...

Comet ISON shaping up to be a spectacular display

Jan 15, 2013

(Phys.org)—Excitement is mounting for astronomers and star gazers the world over as word spreads that Comet ISON may go down in the history books as one of the flashiest ever. First discovered in September ...

Is comet ISON disintegrating?

Oct 06, 2013

Astronomer Ignacio Ferrin, FACom researcher, analyzed the most recent observational data of Comet ISON and has identified clear signatures of what he has called an "impending demise." The so-called light-curve ...

Recommended for you

SDO captures images of two mid-level flares

Dec 19, 2014

The sun emitted a mid-level flare on Dec. 18, 2014, at 4:58 p.m. EST. NASA's Solar Dynamics Observatory, which watches the sun constantly, captured an image of the event. Solar flares are powerful bursts ...

Why is Venus so horrible?

Dec 19, 2014

Venus sucks. Seriously, it's the worst. The global temperature is as hot as an oven, the atmospheric pressure is 90 times Earth, and it rains sulfuric acid. Every part of the surface of Venus would kill you ...

Image: Christmas wrapping the Sentinel-3A antenna

Dec 19, 2014

The moment a team of technicians, gowned like hospital surgeons, wraps the Sentinel-3A radar altimeter in multilayer insulation to protect it from the temperature extremes found in Earth orbit.

Video: Flying over Becquerel

Dec 19, 2014

This latest release from the camera on ESA's Mars Express is a simulated flight over the Becquerel crater, showing large-scale deposits of sedimentary material.

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.