January 2005 - Utah-Astronomy - mailman.xmission.com

Re: comet tails
by Chuck Hards 11 Jan '05

11 Jan '05

My last post just isn't what I really should have said. Astronomy is a precise science, and I am not a precise person and must admit that my interest level isn't what it used to be, and is not nearly as high as most list members these days. I have a good mental grasp of most processes and heavenly motion but don't care to take it beyond that point most of the time anymore (you can only have the same discussion so many times in a lifetime) even though I can do the math. Adult ADD also makes it very difficult to stick with a subject down to the level of intricate detail, lack of unstructured free time for the past few years also adds to my personal editing process. And sometimes I just assume too much. Uncle Carl is 99.99% correct, though once a particle gets to a certain size (he touches on this briefly) then sunlight pressure gives way to orbital motion. Also any motion imparted at the time of ejection from the nucleus can have a dramatic effect on the particle's direction of motion away from the comet at certain sizes. Again here I confess to having drifted off the excerpt, but were the sun's magnetic field lines addressed? The short answer is: two tails, two different raw materials/mechanisms. Jim, I commend you for digging as deeply as you did and taking the time to possibly violate a copyright for our benefit. I in no way meant to minimize or marginalize your posts, you most definitely are the comet master. I'm just here for the donuts. __________________________________ Do you Yahoo!? Yahoo! Mail - You care about security. So do we. http://promotions.yahoo.com/new_mail

1 0

Re: comet tails
by Chuck Hards 11 Jan '05

11 Jan '05

Jim Cobb wrote: > The text below is taken from Comet, by Carl Sagan > and Ann Druyan; I did say "basically", sorry if I offended anyones sensibility. I never know when to be exact and when to generalize, seems one gets corrected no matter which way one goes. Thanks again Jim. __________________________________ Do you Yahoo!? All your favorites on one personal page Try My Yahoo! http://my.yahoo.com

1 0

RE: [Utah-astronomy] Re: Swap meet: ATM stuff?
by David Dunn 11 Jan '05

11 Jan '05

Chuck, I am always interested in ATM stuff and I plan to be to the swap meet. Dave

1 0

Re: Some excellent comet pics
by Chuck Hards 11 Jan '05

11 Jan '05

Jim Gibson asked: > Can anyone explain why there appears to be 2 tails > in the animation that Rich posted? Jim Cobb's explanation is basically correct. The Ion tail, sometimes called the plasma tail, is composed of atomic particles and is driven by the solar wind; it always points away from the sun (more or less). The dust tail, composed of solid particles of dust and rubble, (and the source of earthly meteor showers when we intersect a comet's orbit) basically streams along behind the comet in it's orbital path. Imagining the geometry in your mind's eye, you can see that the two tails can thus diverge by gross angles as the comet travels in it's path. Add to that the changing position of our viewpoint on the moving earth, relative to the comet, and the relative positions of the two tails change even more. Ion tails are typically bluish because they are generating their own photons at a specific wavelength, dust tails whitish to yellowish because they are just reflecting the broad-spectrum sunlight. __________________________________ Do you Yahoo!? Yahoo! Mail - now with 250MB free storage. Learn more. http://info.mail.yahoo.com/mail_250

2 1

Aurora Cam
by Patrick Wiggins 10 Jan '05

10 Jan '05

Small world. One of the other lists I'm subscribed to is for those who like hummingbirds. Seems one of the subscribers likes auroras and just posted this link to a live web cam in a Alaska that watches for auroral displays. http://salmon.nict.go.jp/live/aurora_cam/live_aurora_cam_e.html Looks like there's a small display going on now. Patrick p.s. Must be a bit cool up there as when I first checked it out this afternoon (it's on 24/7) the window the camera looks through was iced over. Brrrrrr...

1 0

First Orion Image
by astrodeb＠charter.net 10 Jan '05

10 Jan '05

I just posted my image of the Orion Nebula in the gallery. I aligned and stacked this image last night and then decided that I'd try a different stack called an Auto Quality Graded stack algorithm in my processing software. It is essentially a weighted average of the 34 frames. Each frame is given a grade quality. I played with the brightness, contrast, stretch functions and this is what I came up with. It is on page 3 of my album. Debbie

3 2

Swap meet: ATM stuff?
by Chuck Hards 10 Jan '05

10 Jan '05

Is anyone interested in me bringing atm supplies, like flat mirrors, motors, parts, focusers, lenses, etc., or is the interest now primarily in commercial products? (of which I might have a few, like binos and complete refractor tube assemblies) Thanks. __________________________________ Do you Yahoo!? All your favorites on one personal page Try My Yahoo! http://my.yahoo.com

3 2

Fwd: Call for Observations January 13-14
by Richard Tenney 10 Jan '05

10 Jan '05

Note: forwarded message attached. __________________________________ Do you Yahoo!? All your favorites on one personal page Try My Yahoo! http://my.yahoo.com

2 1

Re: First Orion shot
by Chuck Hards 10 Jan '05

10 Jan '05

I think this particular stack process is the winner, Debbie. Excellent. What was the optical configuration and mount use? I noticed the contour-gradient lines even in that German comet animation so apparently it's a tough artifact to eliminate. Debbie wrote: > I just posted my image of the Orion Nebula in the > gallery. I aligned and stacked this image last night > and then decided that I'd try a different stack > called an Auto Quality Graded stack algorithm in my > processing software. It is essentially a weighted > average of the 34 frames. Each frame is given a > grade quality. I played with the brightness, > contrast, stretch functions and this is what I came > up with. It is on page 3 of my album. __________________________________ Do you Yahoo!? Meet the all-new My Yahoo! - Try it today! http://my.yahoo.com

1 0

Washington county flooding
by Chuck Hards 10 Jan '05

10 Jan '05

Debbie, are you close to the flood zone? Are you OK? Any other list members close to the flooded area? __________________________________ Do you Yahoo!? Yahoo! Mail - You care about security. So do we. http://promotions.yahoo.com/new_mail

2 1