Way cool interactive website shows what is going on in real time…
Watch it here: http://www.cometison2013.co.uk/perihelion-and-distance/
h/t to Eric Berger
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I still don’t understand how the Earth can look closer to the sun than Mercury, like it did in the other post about this comet.
Tom – imagine viewing the evening sky and Mercury has reached its widest apparent angle to the sun from our viewpoint – it is as far from the sun as it can appear. Now imagine Venus is just coming into view from the solar haze. Its orbit is very much farther from the sun than is Mercury, but because it is just emerging from behind the solar disk it appears closer to the sun owing to viewing angle. Over time as Venus’ orbit causes it to reach its maximum viewing angle from the sun it will catch up to and pass (in angular distance from the sun) Mercury. Mercury will be drawing angularly closer to the sun at the same time so it doesn’t take long.
A couple of days ago the news was depressing as word came that the comet’s nucleus had likely disintigrated. Now the evidence indicates that it’s intact and brightening rapidly. This is getting excited. Latest projections I’ve seen indicate it will likely reach an apparent magnitude of -1 to -4. Maybe even visible during daylight.
I can’t wait to see it and I really hope it doesn’t disappoint. This really could be unprecendented 😉
Bill, I hope you’re right, but I’m holding off on getting excited. In my lifetime, every comet predicted to be spectacular has been a bust.
top branding agency says:
November 27, 2013 at 9:45 pm
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Here’s another source for near-real-time images of Comet ISON and the Sun, from the SOHO (Solar and Heliospheric Observatory) satellite — http://sohowww.nascom.nasa.gov/data/realtime-images.html.
Each image on the page is in a different wavelength. Click on a thumbnail image to get a 512×512 image; click on that to get a 1024×1024 image. The comet may not appear in the tight field of view of most of the channels, but it’s already visible in the L3 view and should be in the L2 view soon. (L2 and L3 denote images from the Large Angle and Spectrometric Coronagraph, an instrument on SOHO.)
Whoops — I made a dumb copy-and-paste editing error. For L2 and L3, substitute LASCO C2 and LASCO C3 in that explanation.
I take it that should Ison plunge into the sun, the flare it would trigger would be pretty spectacular. Just hope it doesn’t point our way.
Bloke down the pub says:
November 28, 2013 at 3:43 am
I take it that should Ison plunge into the sun, the flare it would trigger would be pretty spectacular. Just hope it doesn’t point our way.
I doubt the sun would even notice. Like a fly on an elephant’s backside.
I may not be an expert on orbital mechanics, but when there is still supposed to be 5.5 hours to perihelion and yet velocity is decreasing and distance from the sun is increasing, someone made a mistake on their model…
Latest pic from Lasco C3 as at 12:54 UTC, 40 minutes ago. Its near impossible to get updated images from SOHO right now so this is from a direct depository.
We’ve certainly lost much of the comet coma in the last few hours.
http://s8.postimg.org/dngeu2hzp/20131128_1254_c3_512.jpg
There are recent, if not “live”, updates that ISON has apparently survived to this point.
The cometison2013 site says that they’ve had to update their scripts. “Problems viewing the data? We’ve had to update all the JavaScript files for today so if you’re having problems viewing the data, make sure to refresh the page or try clearing your web browser’s cache.”
SOHO can obviously just give you live images of it’s actual position/condition barring periods where it is behind the sun.
NASA’s site is very slow at the moment, but you can find the images/gif’s here on NASA’s site:
http://sohowww.nascom.nasa.gov/data/realtime-images.html
ESA also has a mirror that’s much faster at the moment.
http://soho.esac.esa.int/data/realtime/gif/
http://soho.esac.esa.int/data/LATEST/current_c3.gif
Ison is now showing up on Lasco C2. This is going to be very interesting.
http://s22.postimg.org/vb247g8dd/20131128_1325_c2_512.jpg
CodeTech says:
November 28, 2013 at 5:06 am
I was going to mention that myself. My take is that it’s the velocity relative a radial from the Sun. If so, it will drop to zero at perihelion and start increasing (or contininue decreasing!) as it heads back out.
If that’s right, 0 velocity will occur at maximum speed (a scalar term) and
maximum kinetic energy.
The distance to the Sun is 0.013 au, That means the gravitational acceleration due to the Sun on the comet is 6,000X what it is on me. I’m tempted to compute that today, though I’ve been trying to take time to work on frequency shifting wind turbine infrasound. Quiet Thanksgiving here!
Ric Werme says….
No, the speed mentioned in the box is the orbital speed, the speed in the orbit. This speed will be a maximum, not be zero, when the comet reaches the perihelion of its orbit.
Well, ISON: this is losing mass.
Not only does the widget show it slowing down as it approaches perihelion, it’s distance from the sun continues to increase, now over 2 million miles! I guess someone screwed up on the math.
SCheesman,
Watch it here: http://www.cometison2013.co.uk/perihelion-and-distance/
and you will see that at this moment the comet’s speed increases and its distance to the Sun is still decreasing!
Jean Meeus says:
November 28, 2013 at 7:06 am
> Ric Werme says….
> No, the speed mentioned in the box is the orbital speed,
Hmm, I might have had the old Javascript running. Just now it was clear that perihelion had happened, reloading the page produced something that’s updating faster and shows the solar distance is still decreasing and speed increasing, as it must.
One of the things about these grazing trajectories is they really whip around Sun/planet, the simulation shows it well. Peak speed will be around escape velocity.
just hit 800,000 mph – that’s a fair old lick of speed!
Thanks, Anthony. A very good Website!
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If my math is correct, that’s a bit over 1/1000 * c (‘c’ being the speed-o-light) … that _is_ moving!
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