Comets in v1.6.0

[duds26]

Most of these new stuff is really liberating for addon developers who previously couldn't do a lot of stuff the way it's presented in the wikibook.

But about the dusk tails, would be handy to set such tales for asteroids or so that come close to the sun because of events. Or a spacecraft that malfunctions and flies towards the sun, starts to vaporise when it's close enough.

(NASA is sending a probe 'into' the sun, not really, just dipping into the sun's atmosphere and mayby some modmakers would make a scenario where stuff goes wrong and the spacecraft vaporises or something.)

Then it would be handy for having that cometary dusk tail.
It could be used in the object timelines and with other classes than comet that also leave such a tail. If the addonmaker doesn't want to use the class comet and needs a cometary dusk tail for all kinds of things.
Like asteroids that can also have such a tail because of the nature and why such a tail is formed.

[t00fri]

Celestia's comet tails develop a dust tail when they are getting closer than ~ 5 AU to the sun. What else?

Fridger

[Cham]

I'm thinking about building some CMOD model of the second comet tail :

comet_tail.jpg

The shape will actually be a fuzzy "dust" model made of points.

Is Celestia really rendering the dust tail (usually curved), or the ions tail (usually a straight tail) ?

[BobHegwood]

Celestia's comet tails develop a dust tail when they are getting closer than ~ 5 AU to the sun. What else?

Fridger

Just curious here Good Doctor...
Has the problem associated with a comet's coma also been modified? This still irritates me to no end, but thus far, I haven't figured out any way to improve the rendering of same.

Thanks, Bob

[duds26]

Celestia's comet tails develop a dust tail when they are getting closer than ~ 5 AU to the sun. What else?

Fridger

Being able to set that distance to something other for objects would be handy.

[BobHegwood]

Just curious here Good Doctor...
Has the problem associated with a comet's coma also been modified? This still irritates me to no end, but thus far, I haven't figured out any way to improve the rendering of same.

Let me re-phrase this question...
Should the coma still be as prominent as it is still shown in Celestia 1.5.1, even when the comet is at 37 AU from the Sun?
Please excuse the repetition here, but I still do NOT understand why the coma would not also dissipate as a comet gets so far away from the Sun.

Any explanation for the Brain-Dead please? Or, is this still an issue which needs to be addressed?

Thanks, Bob

[chris]

Just curious here Good Doctor...
Has the problem associated with a comet's coma also been modified? This still irritates me to no end, but thus far, I haven't figured out any way to improve the rendering of same.

Let me re-phrase this question...
Should the coma still be as prominent as it is still shown in Celestia 1.5.1, even when the comet is at 37 AU from the Sun?
Please excuse the repetition here, but I still do NOT understand why the coma would not also dissipate as a comet gets so far away from the Sun.

Any explanation for the Brain-Dead please? Or, is this still an issue which needs to be addressed?

It's an issue which needs to be addressed. But, this thread is about the new documentation and not bugs.

--Chris

[selden]

I've split the discussion of Comet visualization out of the Documentation topic.

[BobHegwood]

It's an issue which needs to be addressed. But, this thread is about the new documentation and not bugs.
--Chris

Very, very sorry Chris...
Sometimes, I forget where I'm at in a topical discussion. Selden has repaired at my request.

I've split the discussion of Comet visualization out of the Documentation topic.

Again, many thanks for your help, Selden. I really do need to learn how to just shut up for a while.

[t00fri]

Celestia's comet tails develop a dust tail when they are getting closer than ~ 5 AU to the sun. What else?

Fridger

Just curious here Good Doctor...
Has the problem associated with a comet's coma also been modified? This still irritates me to no end, but thus far, I haven't figured out any way to improve the rendering of same.

Thanks, Bob

Sorry, Bob,

no code changes as yet, but this should be addressed, of course.

Fridger

[t00fri]

Celestia's comet tails develop a dust tail when they are getting closer than ~ 5 AU to the sun. What else?

Fridger

Being able to set that distance to something other for specific objects would be handy.

We can't introduce free parameters for almost everything. I have coded the development of a comet tail in a functional form such as to match actual observations and physical calculations. I don't see an overwhelming need for more flexibility here. I have not read a credible physics argument why that characteristic distance should be allowed to vary.

Fridger

[chris]

Celestia's comet tails develop a dust tail when they are getting closer than ~ 5 AU to the sun. What else?

Fridger

Being able to set that distance to something other for specific objects would be handy.

We can't introduce free parameters for almost everything. I have coded the development of a comet tail in a functional form such as to match actual observations and physical calculations. I don't see an overwhelming need for more flexibility here. I have not read a credible physics argument why that characteristic distance should be allowed to vary.

Exactly. Using comet tails for 'special effects' is undesirable. I understand that add-on creators may want comet tail-like effects, but the right way to do this isn't to make the comet tail distance a free parameter. Adding support for particle systems is a better (albeit more involved) approach that won't lead to physical absurdities.

Now, I can see how it would be useful to have some sort of cometary activity parameter. A comet that has made many close approaches to the Sun will be depleted of volatiles and should have a fainter tail than a comet of similar size making its first visit to the inner solar system. However, I don't know that anyone has attempted to characterize comet activity. In the absence of real data, I don't think it's work adding this parameter to Celestia.

--Chris

[ajtribick]

As I mentioned in bug #1864557, it would be good to have the fading dependent on bolometric luminosity rather than visual luminosity when dealing with "exocomets", though this would not be relevant for any objects that are currently known, with the possible exception of the fourth object in the PSR B1257+12 system.

[symaski62]

As I mentioned in bug #1864557, it would be good to have the fading dependent on bolometric luminosity rather than visual luminosity when dealing with "exocomets", though this would not be relevant for any objects that are currently known, with the possible exception of the fourth object in the PSR B1257+12 system.

cel://Follow/PSR%201257+12/2008-06-25T0 ... 2118&ver=2

[ajtribick]

You know, the rest of us use words to explain our points, why can't you?

PSR B1257+12 "D" is currently rendered as class asteroid, however the detection was made by detection of absorption in the object's coma, which suggests it should actually be a comet class object.

[duds26]

Feature:
Multiple tales definable in ssc and path for trailes and timeline possible.
(if a addonmaker wants to make a comet with two tales or a comet that consists of two rocks with different composite that one of them starts and later the second one who could have another appearance like denser or another color.)