comet tails

[selden]

So far, the best I've found online are astronomy course summaries, which just have authoritative statements without references to any research. e.g.
http://www-astronomy.mps.ohio-state.edu ... art22.html

[t00fri]

So far, the best I've found online are astronomy course summaries, which just have authoritative statements without references to any research. e.g.
http://www-astronomy.mps.ohio-state.edu ... art22.html

Thanks, Selden,

I happen to know that lecturers name, possibly I even know him from my various visits to Ohio State U. ...

The course seems concise and the message clear...

Sounds like a good start for the code.

Bye Fridger

[buggs_moran]

Since this topic is picking up again and Fridger seems interested in the possiblility of a change in code I would like to reiterate some ideas I posted earlier in this topic...

The coma is really what we "see" as the comet, the nucleus might show as a bright dot. I have only seen that once through a scope, and frankly I think my eyes were playing tricks on me. About 5 AU's from the sun the dust in the coma starts to reflect light and begins to flouresce due to the UV radiation. To be true to the "visual" aspects of comets we would need a few things.

1. Increase in coma brightness around 5 AU's
2. An ion tail forming a little further in, that points directly away from the sun.
3. A dust tail in the direction of the orbit, but slightly off kilter due to radiation pressure (hence the curl you see in most photographs).

Would a brightness variation based on size starting out at 5 AU's be difficult to code in? As I mentioned above the brightness would be in the coma. Perhaps a fuzzy (that's technical) sphere like the one's Fridger and Toti employed in the galaxy pts files could be useful in the coma and it would brighten (and grow possibly) as the distance to the Sun decreased.

Comets with periods of a few hundreds to some thousands of years - which have therefore already been close to the Sun one or more times - brighten by the inverse-fourth, or even higher, power of the heliocentric distance and are often brighter and more spectacular after perihelion.

[Boux]

From what I have seen in the code, implementation of coma's brightness as a function of distance from Sol should not be difficult to sort out.
I think there is no need for a 'blobbish' approach here.
Brightness of the tip of the comet can be tweaked right where the rendering of the tail is coded. Fuzziness would be a side- perception effect.
I am sure t00fri knows what I mean.

[t00fri]

From what I have seen in the code, implementation of coma's brightness as a function of distance from Sol should not be difficult to sort out.
I think there is no need for a 'blobbish' approach here.
Brightness of the tip of the comet can be tweaked right where the rendering of the tail is coded. Fuzziness would be a side- perception effect.
I am sure t00fri knows what I mean.

Sure, I even wrote similar things further above. But buggs_moran may have a point as to the comet head. I noticed that by increasing the smoothness of the head shape, and also by decreasing the intensity of the comet coloration, the head becomes too faint and also too small. So something has to be done here. But it's probably quite simple. We'll see soon.

Bye Fridger

[WOWspaceISbig]

Okay...it's great that you guys are further improving on the comet tails, but does anybody remember this:

Wow, I come back nearly a week later to find a 3pg thread!

Anyway, those tails look much better. Can anybody show me how to apply them?

[buggs_moran]

Okay...it's great that you guys are further improving on the comet tails, but does anybody remember this:

Wow, I come back nearly a week later to find a 3pg thread!

Anyway, those tails look much better. Can anybody show me how to apply them?

Usually what happens when an issue is taken up around here is deliberation of ideas, mock ups, and someone runs with the project. Downloads and addons don't happen right away. Fridger tempted us early on with his galaxies, fsgregs with his Earth Mark I, and even I with my galactic cores and Mira, etc, but we all have our professional lives that keep interfering with the fun. Damn that real life . This test of patience is especially true when the actual code of the program has to be toyed with. The research, mathmatics, coding, debugging, recoding, compiling (for different OS's mind you) and so on is time consuming and you probably will see the fruits of your post in an upcoming release of Celestia whether it be Chris', Fridgers, etc. At least you got some serious interest, this topic has been put on back burners before to pursue other aspects of the program. The only other way you can push it forward is learning the code and how to compile. Either way patience is the key word.

[WOWspaceISbig]

Ooh... In that case, I think I'll go with patience .