orbits

[draper10701]

Hi.I'm new to this forum and to celestia in general,so i don't kmow if this is the aqppropriate area to post my question .but here goes.I've read a number of threads and followed a number of googled links but havent found an answer to what seems to me a simple question.How do I zero in on the orbit of an asteroid or comet exclusivelyThat is suppose I.m interested in a particular asteroid and want to see it's orbit in relation to the planets but without a lot of other extraneous orbits being shown.how do I dom it?I've seen some ad-ons that show so many orbits that the screen is hopelesssly clutterred so to simplify my question "how do i depict the orbit of asteroidx and ONLY asteroid x"? thanks for any help.

[Vincent]

Hi,

It's not possible yet

But you have 3 solutions :

- You can remove any ssc file of your "extra" folder that contain the class of objects you don't want to see and paste it temporarily into an "extras_no" folder

- You can temporarily rename these xxxxxx.ssc files into xxxxxx.ssc.no

- And if you just want to desactivate a few objects in an ssc file, just add "#' at the beginnig of the object's definition lines

A fourth solution I'm testing at the moment is to create a no_object.ssc file with a "replace" or "modify" command that would desactivate unwanted objects on the screen... If this works, all you have to do is to place this file in your extra directory.

@+
Vincent

[Vincent]

I found a way to desactivate an object during a script using a modify command. I know this command is not new but using it with a script will solve a problem many people had asked for in this forum...

For example, if you don't want Halley Comet to appear on your screen during a script, all you have to do is to create the no_halley.ssc file below and ask users to place it into their "extra" directory :

# no_halley.ssc desactivate Halley Comet

Modify "Halley" "Sol"
{
EllipticalOrbit
{
Period 0
SemiMajorAxis 0
}
}

The problem is that this object will be permanently off during the hole script...

[maxim]

You can only do this with a trick AFAIK (in fact this orbit thing is a bug or at least a missing feature in celestia):

- Switch on the display of orbits.
- Now, as soon as one of the specific orbit selections is checked, orbits are displayed for these type of objects AND for the current selected object.
- Moon orbits are the only ones that are displayed only when the parent planet is selected. So check moon orbits and select the desired asteriod.
- Now the asteriods orbit is displayed, but no moon orbits (as there is no planet selected)

maxim

[MKruer]

I believe that there is an add-on from mostlyharmless that allow you to do query commands, unfortunately it is limited to stars, not planets, but I believe that was one of the future goals.

[Rocket Man]

Asteroid X's orbit is highlighted in red to see it better. Also if you have clasified it as an asteroid, you can go to Render, View options, and down at the bottom is the orbit and labels. uncheck planets and other besides asteroids. And the clutter of other orbits are gone. You can see Asteroid X's orbit clearer.









I hoped this helps.

[draper10701]

Thanks everyone for the help.The suggestion that worked for me was to place a # in front of the first line for each object in the asteroids.ssc.Since in my case ,there weren't that many objects(only the ones from the basic celestia download)this wasn't too tough.I can see how it might be cumbersome if you have a lot of objects in that class to deal with.In future I might try the "extras_no"folder work-around.So having "cleared the air" I made an.ssc file for asteroid 2004 mn4 (of close encunter in 2029 fame)using Selden's guide for converting orbital elements to celestia SSC format as a template,and it worked!Now I'm having fun working with mn4,and have some further projects in mind(ie. showing the asteroid in foreground and earth and moon at time of closest approach)But in any case it felt good to get the program to do what I wanted it to(you never forget your first time).Thanks again for the responses,if I come up with anything worthwhile I'll post it.

[selden]

Don't forget that you need to use orbital elements that are valid at the time of the encounter. The current published orbital elements won't be valid by that time. The asteroid's orbit will have been changed by several flybys of the Earth and Venus.

JPL's Horizons ephemeris service is the best source of updated elements.