Comet ISON Nears Date With Sun

riverat1 writes "Now visible in the morning sky, comet ISON will swing around the Sun on November 28. ISON will pass 730,000 km above the surface of the Sun at closest approach (Mercury's perihelion distance is 46 million km). If it survives its near brush with the Sun it could provide a spectacular sky show from December into January. This NASA timeline shows that ISON will be the most observed comet ever as instruments ranging from a balloon carried telescope to the Hubble Space Telescope to the STEREO satellites will be brought into play. Lowell Observatory astronomer Matthew Knight lays out three possibilities for ISON: spontaneous disintegration before it gets to the Sun (less than 1% chance); disintegration as it rounds the Sun; or survival. If it survives, its closest approach to Earth will be on December 26 at about 1/3 of an AU."

Comments

most observed comet ever

[mcgrew]

How visible will it be to the unaided eye? And where will it be the most visible? I was in southern Thailand when this comet came by, and was puzzled when the newspapers said it was "disappointing". It was the brightest thing in the night sky except the moon where I was.

Re:most observed comet ever

[umafuckit]

They probably said it was disappointing because hopes are always raised for a great, horizon to horizon, comet. It was suggested that ISON might have been one such great comet. I think it never rose above a binocular object on its way towards the sun, but things could change on the outbound journey.

Re:most observed comet ever

[Iskender]

Actually, ISON is still on its way towards the sun. And it has been observed with the naked eye. Still not a great comet, though.

Re:most observed comet ever

[Zocalo]

It's currently quite visible to the naked eye, if you can get away from any significant light pollution. You'll need to look due East just before dawn for the best views; ISON is currently passing by Spica in the constellation of Virgo. If you've got a reasonable camera that can do manual exposures and a tripod, then you'll get a much more impressive image by using a longer exposure and a mid-telephoto focal length; a 70-200mm range is currently ideal depending on how much of the tail you want to try and capture, or go for a longer length if you just want to capture the quite spectacular coma. Open the lens to the widest aperture, manually focus to infinity (I use a bright star for this), keep the exposure down to about 20s and adjust the ISO to suit.

Re:So.. wgats the chance it will hit earth then?

[SJHillman]

Considering 1/3 of an AU is only slightly closer than Mars' closest approach to Earth, and several million miles more than Venus' closest approach to Earth, I'd say it's close enough to 0 to be considered a rounding error.

"Spontaneous"?

[fatphil]

That word does not mean what you think it means.

It's bombarded so aggressively, it's having its surface ripped off it to create that enormous tail, and it's suffering from ever greater gravitational tidal forces - that's about as far as you can get from happening without apparent external infuence.

Re: "Spontaneous"?

[Rhurazz12]

If I didn't know any better, I would say that you have feelings for this Comet.

Re:"Spontaneous"?

[fatphil]

The centre of mass of the fragments will continue in the same path initially. However, the smaller the fragment, the more the solar wind will affect it. Some groups of comets that appear at about to have a very similar path have been conjectured to be just components of much larger comets that have fragmented (e.g. the Kreutz group).

Some Info: Dark Sky vs. Twilight Viewing

[Iskender]

Wikipedia says that thing was fourth magnitude when visible in the night sky: that's not very bright. But it can *seem* bright in good dark skies. Dark skies were, of course, much more common in the seventies than they are now. Light pollution eats comet tails for breakfast.

Now, few comments (nice typo...COMETS) are really impressive in the night sky. Hale-Bopp was one exception. Most are impressive only close to the sun - this was true of Kohoutek, and will be true of ISON if it survives.

The predictions for ISON place it very close to Kohoutek in terms of brightness, actually. This brightness is for the closest approach to the sun - meaning best viewing is right after sunset, or just before sunrise. If things pan out, we might get to see a huge, bright tail against a backdrop of somewhat dark sky.

Comet ISDN?

[Anonymous Coward]

Old news. Tell me when Comet ADSL is heading our way.