Tuesday, November 26, 2013
Has Comet ISON disintedgrated? (or is it disintedgrating)
There has been a lot of buzz in the astronomy community over the last 8 hours of so over news that comet C/2012 S1 ISON may be breaking up/ has already broken up. There are several elements to this.
A CalTech team using the IRAM millimeter telescope in Spain has reported a 20 fold fall in molecular emission lines from 21 November to 25 November. They interpret this as a disintegration of the comet. The TRAPPIST team reports a fall in dust production rates by a factor of 3, AfRho measurements by the CARA team suggest nuclear erosion. Terry Lovejoy has measured strong non-gravitational forces which may suggest a breakup. Dan Fishers notes an alternate view of the CalTech results.
Against this the comet looks healthy and brightening in the STEREO images. This could be due to the comet being an expanding cloud of reflective dust though.
BPEarthWatch.com (latest) Makes good sense to me. Too much subjective media blogs are happening at this time. If Nasa has been withholding radio images for such a long time, what is this saying ? Coverup of something BIG is happening. Jessie has the comet at 18,000 miles diameter.
What you are sing in the H1A images is not the cometary nucleus, but the atmosphere of dust and gas around the nucleus, the coma. The nucleus is at most 5 km in diameter, but the coma is much larger.
NASA hasn't been withholding any radio images, the radio telescope data come from completely independent astronomers (and are not images, but radio spectra).
All the amateur images and measurements (and there has been lots of serious activity over the past months), give results of a smallish comet, gas rich and dust poor.
The H1A images show the comet growing slowly in brightness, but with the resolution of the H1A camera, we can't say if the nucleus is intact for a few more days (although the latest beacon image suggests it is staying intact)
Can anyone else see it in the picture ?
No, it will not be seen in Australia at all, see the posts here http://astroblogger.blogspot.com.au/search/label/C%2F2012%20S1%20ISON
What you saw was probably a meteor, there are no unaided eye comets around at the moment.
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