ISON Image of the Week

Still In One Piece  (Oct 21, 2013)

In this beautiful up-close view of Comet C/2012 S1 (ISON), courtesy of the Hubble Space Telescope, we can see that Comet ISON is still very active and very much in one piece!
[Image credit: NASA, ESA, and the Hubble Heritage (STScI/AURA)]
As we have mentioned once or twice, for a few months now there has been ongoing speculation that comet ISON's demise is imminent. The CIOC has always been clear that the fate of this comet is very much in the balance - though we do lean towards thinking it will survive perihelion - and certainly there always remains the possibility that those who are repeatedly making these claims may eventually be correct. But as of right now, comet ISON continues to perform well and remains in one piece - and that's not just speculation!

On October 9, 2013, the Hubble Space Telescope again pointed itself in the direction of comet ISON and took some spectacular images! We last saw images of comet ISON from Hubble in April of this year (with the returned images stirring a little controversy) while the comet was still over 4 AU (~370-million miles, ~600-million kilometers) from Earth. When these latest images were recorded, the comet had more than halved that distance, affording us a much closer view. The picture we show here is a combination of images taken in red and blue filters over a 29-minute period (click for a large version).

Certainly we can see that the comet is in one piece - or was on that day - and remains so from what we see in the most recent images taken by amateur and professional astronomers. The Hubble cameras don't allow us to be able to resolve the nucleus of the comet itself because the nucleus is only maybe 1km - 2km (0.6 - 1.2 miles) in diameter, and is shrouded in a rather dense and sunlight cloud of dust and ice particles that are being released from the comet. However, there's no indication in this image that there is any more than one single component at the center of ISON's diffuse coma.

It's worth noting that Hubble is not the only spacecraft that has been observing comet ISON lately. According to our CIOC Observing Calendar, the NASA SWIFT spacecraft has been making more observations lately, and the SOHO and STEREO-A satellites are monitoring ISON continuously at this point. In addition, the Chandra x-ray telescope is lined up for observing ISON in the coming weeks (beginning November 3, 2013), and the STEREO-B spacecraft is scheduled to begin a series of daily 180-degree rolls in order to observe the comet. We anticipate at least a handful of other spacecraft joining in the observing fun as comet ISON makes its way towards perihelion on November 28, 2013! Lots of eyes in the sky, plus lots of eyes on the ground, equals lots of great science to be learned! Stay tuned to this website, as things should get pretty exciting over the next 6 - 8 weeks...

Every week this year we will put up a new image related to Comet C/2012 S1 (ISON). If you have a cool image you'd like us to consider, please send it to, along with a description and any credits you would want applied. We'll contact you if we choose to use your image on the CIOC Website.

See our ISON Image of the Week Archives for earlier picks!