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Glen A W
sage


Reged: 07/04/08

Loc: WEST VIRGINIA USA
Comet ISON - Cooked well done?
      #6215424 - 11/25/13 03:24 PM

It was looking so good the past couple of weeks, but now the news is sounding rather poor. They make it sound like the reduction in molecular emission lines is pretty telling about the comet having disintegrated.

Predictions, opinions, or prophecies, anyone?

http://www.skyandtelescope.com/news/home/Comet-ISON-Becomes-a-Nail-Biter-2333...

http://www.isoncampaign.org/Present


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dyslexic nam
Carpal Tunnel
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Reged: 01/28/08

Loc: PEI, Canada
Re: Comet ISON - Cooked well done? new [Re: Glen A W]
      #6215442 - 11/25/13 03:32 PM

Booooo!

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Unknownastron
professor emeritus
*****

Reged: 04/06/05

Loc: CatsEye Observatory,Rural Sout...
Re: Comet ISON - Cooked well done? new [Re: dyslexic nam]
      #6215548 - 11/25/13 04:13 PM

I have learned one fact over years of comet predictions of too many comets to mention: some of the predictions are dead on, some are partly right, some are wrong. Comets remain too unpredictable to know what will happen until it does. Not that predictions should not be made, just that scientific study of comets is at a similar level to weather predictions a century or more ago. Trying to predict anything more than a very short time in the future is not reliable.
Clear skies and clean glass,
Mike


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djeber2
Pooh-Bah
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Reged: 07/02/04

Loc: Cloudy Midwest
Re: Comet ISON - Cooked well done? new [Re: Unknownastron]
      #6216031 - 11/25/13 08:25 PM

Glen, thanks for the articles, does not sound promising at this time. I am glad I saw it when I did.

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BrooksObs
professor emeritus


Reged: 12/08/12

Re: Comet ISON - Cooked well done? new [Re: djeber2]
      #6216287 - 11/25/13 10:55 PM

Watch the SOHO images November 27 to 29 , paying particular attention to the size of the camera's "bloom spikes" relative to the comet's head. Their dimensions are indicative of the comet's true brilliance at the time. The longer the bloom spikes, the brighter the comet is. When in the camera's field of view, brilliant objects like Venus (at superior conjunction) will have bloom spikes that span a large part camera's field. If ISON's spikes are very long on the 28th and remain fairly large throughout the 29th, then expect a show in the morning sky beginning toward the end of next week. If not...oh well.

If you are unsure what to be looking for on the SOHO images, take a look back at Comet Lovejoy's SOHO image loops. I'll try posting my interpretation of what I'm seeing (or not seeing!) at some point during the 28th, here on Cloudy Nights.

BrooksObs

Edited by BrooksObs (11/25/13 10:56 PM)


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StarWars
Mr. Postmaster Man
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Reged: 11/26/03

Loc: At the Gym >Spudtastic<
Re: Comet ISON - Cooked well done? new [Re: BrooksObs]
      #6216322 - 11/25/13 11:27 PM



Most likely Cooked ....
730,000 miles from the Sun is Toasty close...


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Tonk
Postmaster
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Reged: 08/19/04

Loc: Leeds, UK, 54N
Re: Comet ISON - Cooked well done? new [Re: StarWars]
      #6216548 - 11/26/13 05:29 AM

Today on Comets-ML (yahoo group) the profesional astronomers are discussing the meaning of the rapid drop in production of various volatiles as measured using millimeter wavelength radio telescopes. Many are suggesting that the nucleus is now breaking up. This is backed up with some other experiments but yet others don't appear to be indicating this (possible lack of resolution and the effect of time dependency when looking at visual wavelenght data confuses things. Whereas millimeter wavelenth data is measuring events happening now)

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bartlebobton
newbie


Reged: 11/26/13

Re: Comet ISON - Cooked well done? new [Re: Tonk]
      #6216694 - 11/26/13 09:07 AM

Hi ...

I tripped over this site through my excitement over Comet Ison... From my very very limited school boy physics... If you have an object moving through space at 60miles per/sec...that is anticipated to increase to a speed perhaps 200 miles p/sec ...why would anyone be surprised if Ison broke up... The friction at those speeds must be quite a force on an object composed of ice and rock, factor in the gravitational pull of the sun + temperature... why would it be a surprise to anyone if the comet does not pull through...and simply breaks up....
Reading some articles, not on these boards, makes me think astronomy is an art form and not a science...

Fingers and legs crossed though.... Hall (Hale) Bop was quite special...I was sad to see it go...there is something quite magical about it...


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MessiToM
scholastic sledgehammer
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Reged: 12/21/09

Loc: Huntingdon PA
Re: Comet ISON - Cooked well done? new [Re: bartlebobton]
      #6216762 - 11/26/13 09:41 AM

Umm.......no ^. It isn't like this is a 2 foot wide snowball ISON is several miles wide and may have enough material to burn off a lot and still be intact. Also. Where do you think FRICTION happens in space? There isn't any atmosphere.


Also. If this breaks up pre rather than post periphelon I will be SO bummed out!

Edited by MessiToM (11/26/13 09:45 AM)


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Octans
member


Reged: 08/13/09

Loc: Santa Barbara, CA, USA
Re: Comet ISON - Cooked well done? new [Re: bartlebobton]
      #6216776 - 11/26/13 09:46 AM

Quote:

Hi ...

I tripped over this site through my excitement over Comet Ison... From my very very limited school boy physics... If you have an object moving through space at 60miles per/sec...that is anticipated to increase to a speed perhaps 200 miles p/sec ...why would anyone be surprised if Ison broke up... The friction at those speeds must be quite a force on an object composed of ice and rock, factor in the gravitational pull of the sun + temperature... why would it be a surprise to anyone if the comet does not pull through...and simply breaks up....
Reading some articles, not on these boards, makes me think astronomy is an art form and not a science...

Fingers and legs crossed though.... Hall (Hale) Bop was quite special...I was sad to see it go...there is something quite magical about it...




Friction isn't really a factor since it's passing through a near vacuum -- the solar wind / corona of the Sun is very tenuous and is negligible when compared to other factors like the heat and tidal forces. I don't think it's so much that everyone would be surprised if it broke up as that everyone's still holding onto hope that it survives, given that we seen comets like C/2011 W3 (Lovejoy) in the past.


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dyslexic nam
Carpal Tunnel
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Reged: 01/28/08

Loc: PEI, Canada
Re: Comet ISON - Cooked well done? new [Re: Octans]
      #6216799 - 11/26/13 09:57 AM

And for the record, I haven't yet read a post on ISON's possible/probable demise that expresses surprise. More like disappointment. People are simply hoping that ISON pulls through and puts on an amazing show.

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Tyranthrax
sage


Reged: 04/22/13

Loc: Reno, NV
Re: Comet ISON - Cooked well done? new [Re: dyslexic nam]
      #6216852 - 11/26/13 10:20 AM

when ever I root for a team or get my hopes up for a win I am like the kiss of death on that team. I've been chering for this thing for a few months now. . . I base my predition on no science wat so ever, just my record. I hear a fat lady warming up for ISON.

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bartlebobton
newbie


Reged: 11/26/13

Re: Comet ISON - Cooked well done? new [Re: Tyranthrax]
      #6216875 - 11/26/13 10:35 AM

Hey... thanks for the friction/atmosphere lesson.... Am I right in saying there is resistance from the solar wind(s)...but it's not significant.... Perhaps that's a bit of generalisation ....BB

Edited by bartlebobton (11/26/13 10:38 AM)


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swalker
Imaging Editor - Sky & Telescope
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Reged: 01/22/07

Loc: 42.9225°N, 71.2242°W
Re: Comet ISON - Cooked well done? new [Re: bartlebobton]
      #6217009 - 11/26/13 11:32 AM

Don't write off the comet just yet. While those science observations are discouraging, we'll all know how it will shape up come Thursday. It does make for some late drama, that's for sure...

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MessiToM
scholastic sledgehammer
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Reged: 12/21/09

Loc: Huntingdon PA
Re: Comet ISON - Cooked well done? new [Re: swalker]
      #6217030 - 11/26/13 11:49 AM

Thats for sure. A nail biter!

bartlebobton watch this .gif of solar wind affecting ISON and ENCKE
http://spaceweather.com/images2013/25nov13/ison_encke_nov19_23_crop_hi1a.gif?...


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boandpokey
sage
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Reged: 07/25/13

Loc: Auburndale, Fl
Re: Comet ISON - Cooked well done? new [Re: MessiToM]
      #6217053 - 11/26/13 11:58 AM

all signs point to disintegration what a shame. I never got to see it. the weather here in the nonsunshine state the last 2 weeks has been terrible

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GlennLeDrew
Postmaster
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Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
Re: Comet ISON - Cooked well done? new [Re: boandpokey]
      #6217122 - 11/26/13 12:34 PM

The matter of 'friction' has been partly addressed, that being the the solar wind is a very very good vacuum. The solar wind, blowing at up to 400 km/s, will have a virtually instantaneous impact on the atoms and molecules driven off the nucleus, they being accelerated to the solar wind speed in very short order. For the dust particles, as we progress up in size from the really fine stuff to millimeter-size bits, the acceleration becomes progressively slower. For instance, the bits which result in meteor showers (when intersected by Earth) basically travel along the comet's orbit for years, gradually dispersing into an increasingly wide stream.

As to the gravitational force of the Sun, its only impact is the tidal stress resulting from the difference in attraction between the day and night sides on the comet. The day side is attracted more strongly than the opposite side, and this stress can pull the body apart. This is what happened to comet Shoemaker-Levy 9 when it passed very near to Jupiter not long before before its final plunge into Jove's atmosphere.

If you were to follow the comet's path--but with very good thermal protection--even at perihelion you would be in free fall and hence feel weightless. If your feet were pointing at the Sun, they would be attracted a tiny bit more strongly than would your head, but you would not feel this awfully slight stretching over a mere 6 feet. (Near the event horizon of a black hole, though, you would be ripped apart.) Over an object diameter of some kilometres, however, the gravitational gradient and hence tidal stress is sufficient to overcome the comet's weak self gravity and internal cohesion.


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Tonk
Postmaster
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Reged: 08/19/04

Loc: Leeds, UK, 54N
Re: Comet ISON - Cooked well done? new [Re: GlennLeDrew]
      #6217264 - 11/26/13 01:46 PM

The news as of this afternoon is ISON's brightness has stopped declining and is showing a very slow rise. However one commentator states its only showing brightness curve of a slowly expanding dust cloud (Comets ML)

Its now entering the FOV of the STEREO-B COR2 camera (bottom left)

http://stereo.gsfc.nasa.gov/browse/2013/11/26/behind/cor2/1024/20131126_15392...


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boandpokey
sage
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Reged: 07/25/13

Loc: Auburndale, Fl
Re: Comet ISON - Cooked well done? new [Re: Tonk]
      #6217308 - 11/26/13 02:15 PM

http://sohowww.nascom.nasa.gov/data/realtime/c3/1024/latest.html

is that ISON, the faint fuzzy dot in the lower left??

Edited by boandpokey (11/26/13 02:17 PM)


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boandpokey
sage
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Reged: 07/25/13

Loc: Auburndale, Fl
Re: Comet ISON - Cooked well done? new [Re: boandpokey]
      #6217319 - 11/26/13 02:21 PM

Tonk

thanks.. either way. very unimpressive compared to Lovejoy


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