I'm having a problem with Pluto's orbit

[Sky Pilot]

I'm not sure which of my many addons did this, but Pluto's orbit isn't showing correctly. Anyone have any ideas how to fix it?

[Hungry4info]

What add-ons do you have?

[Sky Pilot]

All right, you asked for it. I'm using Celestia 1.5.1, and have added...

For the sun...
rthorvalds_sun

For the Earth...
RealisticEarth_v4_dds
clouds-121303-2kpng
earthlights
1k_2k_4k_moon

For Mars...
mars-16k-050104
2k-DiemosPhobos

For Jupiter...
4krealj
jt2
callisto2k
europa_2k_4k_8k
2k_4k_ganymede
1k_2k_4k_Io

For Saturn...
th_saturn_vol1
1k_2k_4k_dione
enceladus8kalbjpg

For the Kuiper Belt...
HydraNix
2003_ub313
Sedna

For asteroids...
MajorAsteroids
PHA.ssc
NEO.ssc

For Nebula...
boomerang2
NGC3132_EightBurstNebula
ScorpioNebula_CMOD

For stars...
CygOB2
starsdb2.1c

For spacecraft...
new_horizons_dds_v2.4
pioneer_full
voyager_full
Callisto2k

I'm running on Windows Vista Home Premium; T9300 Intel processor; 4GB RAM; dual Nvidia 8700 SLI cards; 250GB HD.

So, why would the orbit of Pluto show only a partial orbit?

Thanks
Sky Pilot

[Sky Pilot]

I think I'm narrowing in on the problem, and it seems to be with Jestr's New Horizons add-on, which includes a new Pluto and Charon and new ssc files. I installed Jestr's add-on using the instructions that came with it, and I moved the jpleph.dat file to the Celestia>data folder as instructed. Now when I launch Celestia and hit Return and type "Pluto", I get two objects to select at the bottom of the screen: "Pluto" and "Pluto-Charon." The screenshot below shows the orbit of "Pluto-Charon" selected in red, and the truncated (pie shaped) orbit of "Pluto" in blue at the top of the screen. It appears that I now have two Plutos in my solar system, and the old Pluto orbit is in conflict with the Pluto-Charon orbit. Can anyone tell me how to fix this? I didn't see any instructions in Jestr's add-on for how to remove the old Pluto.

Thanks
Sky Pilot

[BobHegwood]

Sky Pilot,

I don't know if it is related or not, but I put a note on the New Horizons download so that others might beware of
this problem. Could have something to do with the re-classification of Pluto in more recent releases?

[selden]

Jestr's Pluto has a pie-shaped orbit because the JPL ephemeris he provides defines only part of an orbit. Celestia connects the ends. I think this is a case where it would be better if it didn't.

Jestr's New Horizons Addon was created before Celestia supported SSC barycenters (ReferencePoints). I suspect he'd do it differently now.

[Sky Pilot]

Ok, but it's interesting that the two orbits (Pluto and Pluto-Charon) don't come anywhere CLOSE to alignment.

[asteroid]

Darn, I wish I read this before I installed this add-on. (

Has anyone found a way to repair poor Pluto?
First his demotion from Planet status, now his orbit has been hijacked. Not good times for little Pluto.

I'm seeing the same pie-orbit and would like to be able to fix it.

[jogad]

Hello

Don’t cry!

The position of Pluton was right in Celestia 1.4.1, but now reference planes have changed. If you want to see Pluton at its correct place in celestia 1.5 and 1.6 you must change the Pluto.ssc file in the new_horizons_dds folder.
Here is the new content of this file.

Code: Select all

Modify "Pluto" "Sol"
{
        Texture "jpluto.dds"
        NormalMap "jpluto_normal.dds"
        SpecularColor [ 0.135 0.12 0.08 ]
        SpecularPower 9.5

    OrbitFrame
    {
        EclipticJ2000 { Center "Sol" }
    }
    CustomOrbit "pluto-jpl"
}

Modify "Charon" "Sol/Pluto"
{
    OrbitFrame {
       EquatorJ2000 { Center "Sol/Pluto" }
    }

    BodyFrame {
        EquatorJ2000 { Center "Sol/Pluto" }
    }

}

AltSurface "Jestr Charon" "Sol/Pluto/Charon"
{
   Texture "jcharon.dds"
        NormalMap "jcharon_normal.dds"
        SpecularColor   [ 0.135 0.12 0.08 ]
        SpecularPower   9.5
}


And now all should be ok! Without the fix, this beautiful view with New Horizons, Pluto ant Charon would be impossible to see!
cel://Follow/Sol:New%20Horizons/2015-07-14T11:50:05.94883?x=vPDL2SjXuZl+&y=gVJPCyHAbVsR&z=W5zBSil0RnD4AQ&ow=-0.386873&ox=0.159162&oy=0.886258&oz=-0.198857&select=Sol:New%20Horizons&fov=28.498949&ts=0.000000&ltd=0&p=0&rf=38279&lm=2017986688&ver=2

Obviously the complete addon must be installed to enjoy that.

Bye

[asteroid]

I edited the Pluto file as you suggested.
Here's the screenshot of Pluto's orbit after that change:

[jogad]

Hi

No such a thing for me. The orbit is always a piece of the complete one, but is open.

But the most important in my opinion is that now, the orbit of Pluto matches very well the orbit of the barycenter Pluto-Charon and is at the right place in space. Without the change the resulting orbit was completly false!

Orbit of Pluto alone


Orbit of Pluto and Pluto-Charon by selecting it with the “enter key” method.


Regards

[asteroid]

Well now I'm really confused.

None of my planets line up like yours. In your photo, Saturn is positioned to the right of Sol. Jupiter then is on the far side relative to the position where you took the screen shot as is Neptune, but it is slightly behind and Left.

If I set my position so Saturn is to the right of the sun as you pictures show, Jupiter is on my side of the sun. Uranus and Neptune are Far Left, and Pluto is behind.

cel://follow/Sol:Pluto/2008-12-11T19:51 ... 6562&ver=2

Screenshot with orbits and planet tags:

http://i34.tinypic.com/2meyfex.jpg

[asteroid]

I just noticed something else. On my screenshot you see Pluto on that bottom corner of the "pie shaped" orbit. If I reverse time and watch the planets orbit, Pluto will continue off that drawn line and seemingly orbit its path connecting to the far corner of the 'pie' after traveling around the sun. BUT.... if I move forward in time from today Pluto follows his path across the draw line, then when he hits that far left corner where the drawn orbit heads to the sun Pluto disappears!

According to Celestia Pluto dies on Monday Jan 11 2100 just about midnight


<insert Deathstar / Alderaan joke>

[jogad]

 
Pluto's death is normal. The jpl file of the addon defines its orbit only from 1799 to 2100.

I tested your Url. It is easiest with it. Here is the result



The respective positions are Ok but the distance is different and also the stars behind.
Very strange!

Getting closest and rotating a bit, I finally get the same image than you:


Are you sure that you did not move the mouse beetwen capturing the screen and copying the url?

And remember that the modification fixes ONLY the place of Pluto in the sky and NOT any graphic bug.

[asteroid]

Are you sure that you did not move the mouse betwen capturing the screen and copying the url?

100% sure. In fact I just copied that URL from the post and dropped it into a fresh session of cel. Same as the image posted.

Weird huh?

[selden]

The jagged orbit path is not a bug, it's a feature. It was an explicit design decision to interconnect the ends of the drawing of the defined orbital path.

The path drawn by Celestia is not the same as the orbit followed by the body. The path is for visual convenience only. At most, it shows a single revolution of the specified object abound its primary. If the supplied trajectory is incomplete, an incomplete orbital path is drawn. If the trajectory is non-repeating (as is the case for the Sun's orbit around the solar system barycenter and for the Moon's orbit around the Earth), then there will be a straight line drawn from the end of that first orbit back to the beginning of that first orbit.

I'm a little surprised that it's pie-shaped in some cases, but c'est la vie.

I hope this clarifies things a little.

[chris]

Well, I wrote a detailed post about this bug, but it got trashed when my internet connection died while pressing 'Submit'

Anyhow, the wedge shape is a Celestia bug. It's caused by the fact that Celestia is trying to plot an entire 248-year orbit of Pluto when inadequate data is in the JPL ephemeris. Celestia tries to plot the orbit starting from a date near the present, a time range of 2008-2256. But the JPL ephemeris in the add-on only covers years up to 2100. Positions at the out-of-range dates are zero, thus the wedge shape. Celestia needs to be smarter about plotting orbits when the data covers only a limited span of time. For a short term fix, these orbits could be treated like aperiodic orbits, where the endpoints aren't connected. I'm planning a significant rewrite of the orbit plotting code after 1.6.0; it will address the problem reported in this thread and many others (like the 'kink' in the Moon's orbit.)

--Chris