The weirdest world for Celestia - help with XYZ

[rthorvald]

Help with XYZ needed:

Off on a Comet - a journey through planetary space
---------------------------------------------
Jules Verne wrote this novel in 1877, and as far as i know, it is the first story ever written on a tour of our solar system. I read it when i was nine years old, and it was this book that actually got me interested in space: it is both an adventure, a travel-log, and a popularisation of what was known about our solar system at the time. So i have built an add-on, just to see what it would have been like to be there... Here?s a screenshot:


(More images and info about it on my website).


Comet Gallia may well be the most improbable object ever to be seen in Celestia, but it has been great fun to make it, and now i am almost finished - just need to fine-tune the ssc before i can release it.

However, instead of having Celestia giving it a generic orbit, i would very much like to reproduce the orbit Verne described in his story. This will make it possible to lock onto the comet, speed up time, and get a great tour of the solar system, intersected by four planets - sort of like with a script.

Luckily, he supplied the reader with a lot of data - i do not know if it is realistic, but if so, it is enough to construct an orbit.

One problem, though. I am completely ignorant on how to make an XYZ. I do not understand the terminology, and i am a designer, with no math training at all. So, i am hoping that maybe someone here on the forum might take the time to help me.

I do not know how much work this is, so i realize i do not know exactly what i am asking. But i do hope someone with the know-how will think this is as fun as i do...

I do not need an exact reproduction, but i need 8 points in space and time to be included for the XYZ to match the story. They are described below. I have translated all gregorian dates to julian, and miles and leagues to kilometers.



THE ORBIT
---------------------------------------------
The XYZ should run from 31. december 1877 to 01. january 1880. Julian: from 2406984.5 (one day before passing Earth for the first time) to 2407715.65806 (one hour after passing Earth for the second time).

I would like to reduce the minimum distances to the planets Venus, Jupiter and Saturn. The reason is that Vernes fiction does not match his data: for example, at closest approach to Jupiter, the travelers speak of the planet as "a glorious orb in the sky", whereas in Celestia, at a distance of 50 000 000 kilometers, it is really just a bright dot. So Verne took some artistic freedoms for dramatic effect, and to illustrate the story, we need to do the same - and tweak the numbers enough that the worlds becomes recognizable discs when viewed from the comet surface.

Vernes real numbers are noted first, with my desired numbers in [parentheses].
If my numbers makes the orbit unworkable, stick to Vernes numbers.

Note: Comet Gallia moves in the plane of the ecliptic, in a retrograde, parabolic orbit that changes into an ellipse at julian date: 2406985.61639 (upon impact with the Earth). The ellipse is an exact 2-year period, and happens only once.

EIGHT SPOTS IN SPACE & TIME
-------------------------------------------
1. Julian date: 2406985.61639
Ascending node,
Distance to Earth: 0 km at the Rock of Gibraltar, traveling east.


2. Julian date: 2406999.5
Perihelion

3. Julian date: 2407002.5
Closest approach to Venus at a distance of: 4000000 km [WANTED: 50000 km ]


4. Julian date: 2407016.5
Passes descending node

5. Julian date: 2407272.5
Closest approach to Jupiter at: 50000000 km [WANTED: 3000000 km ]


6. Julian date: 2407333.5
Closest approach to Saturn at: 668000000 km [WANTED: 7000000 km ]


7. Julian date: 2407364.5
Aphelion

8. Julian date: 2407715.6164
Closest approach to Earth at distance: 720 km (above Mediterranean)
Orbit changes, Gallia never returns.

GALLIA SSC:
---------------------------------------------
# COMET GALLIA ----------------------
"Gallia" "Sol"

{
Class "comet"
Texture "th_gallia.ctx"
NightTexture "th_gallianight.ctx"
Radius 362.10
# Beginning 2406984.5 # december 31. 1877
# Ending 2407715.65806 # january 1. 1880

Atmosphere {
Height 15.9
Lower [ 0.43 0.52 0.65 ]
Upper [ 0.26 0.47 0.84 ]
Sky [ 0.40 0.6 1.0 ]
CloudHeight 6.7
CloudSpeed 75
CloudMap "th_galliasky2k.png"
}

CustomOrbit "Gallia"
EllipticalOrbit
{
Period 2.0000
SemiMajorAxis -5.5 # Real: -3.6793 = 550050000 kilometers. Adjusted for orbit of Saturn
Eccentricity 0.9
Inclination 0
AscendingNode 348.739
ArgOfPericenter 110.000
MeanLongitude 231.915
Epoch 2406985.61639 # january 01. 1878 at 02.00 hours 47mins 36secs
}

RotationPeriod 12
Obliquity -23.45
RotationOffset 280.5
Albedo 0.65
}



ADDENDUM:
---------------------------------------------
Verne included lots of data on the orbit. If it is of any use, I have collected it here: http://runar.thorvaldsen.net/celestia/temp/vernedata.txt


THE BOOK:
---------------------------------------------
It can be downloaded free from this address:
http://www.gutenberg.net/etext98/comet10.txt

If anyone is interested in helping out, reply here or by mail.
Thanks.

-rthorvald

[t00fri]

Help with XYZ needed:

Off on a Comet - a journey through planetary space
---------------------------------------------
Jules Verne wrote this novel in 1877, and as far as i know, it is the first story ever written on a tour of our solar system. I read it when i was nine years old, and it was this book that actually got me interested in space: it is both an adventure, a travel-log, and a popularisation of what was known about our solar system at the time. So i have built an add-on, just to see what it would have been like to be there... Here?s a screenshot:

http://runar.thorvaldsen.net/celestia/screens/gallia2.jpg
(More images and info about it on my website).

I find this beautiful and simply "cultural". No idea why there is not more resonance from people ...

The subjects we can read in the forum recently, are definitely of the "less inspiring type":

-- Help!! it won't run:O
-- Um...Pass me the syrup, please
--problems with Celestia 1.2.5 prerelease (!)
--OK Selden
--version 1.3.2pre7 don't work right
--help please

After > 2 1/2 years of being a member here, I can definitely remember more inspiring threads!

Bye Fridger


--

[bh]

This looks a great bit of fun...why not! I'll be keen to have a go...in a balloon! Cripes!

[Rassilon]

These are the kinds of addons I want to see more of from the community...Well and the other alien worlds...

Verne was one who inspired dreams....

This might help some...It is off seldens resource page...

http://www.lns.cornell.edu/%7Eseb/celes ... mplate.txt

[rthorvald]

This might help some...It is off seldens resource page... http://www.lns.cornell.edu/%7Eseb/celes ... mplate.txt

Rassilon, thanks; i suspected Selden might have something like that, but i must have overlooked it.

Now, i have used it to obtain the planet positions, but i still need to subtract for the positions of the comet relative to the planets, and i do not know how to define the empty spots in space for perihelion and aphelion for this tool.

As of now, my XYZ looks like this:
----------------------------------------
# DISCOVERY: 1877-Dec-31 00:01 (julian: 2406984.5) in constellation Gemini
2406985.615277778 -3.138783496359436E+07 1.436985807878960E+08 3.941224502718449E+04
# PERIHELION at: 1878-Jan-15 00:01 (julian: 2406999.5)
2407002.500694444 -1.613752782951578E+07 1.063439344460240E+08 2.350033451545775E+06 # subtract 50000 km for distance to VENUS
# DESCENDING NODE at: 1878-Feb-02 00:01 (julian: 2407016.5)
2407272.500694444 4.987009345696313E+08 -5.738184846215640E+08 -8.873118584540814E+06 # subtract 3000000 km for distance to JUPITER
2407333.500694444 1.418327510966303E+09 9.850690560818191E+07 -5.791546129099870E+07 # subtract 7000000 km for distance to SATURN
# APHELION: 1100000000 km from SUN
2407715.615972222 -3.007461972019341E+07 1.439835870816055E+08 3.841515245953202E+04 # subtract 720 km for distance to EARTH
# Leaves solar system
----------------------------------------
Another thing is, these data does not place the comet at Earth at the starting date; this means there?s?something i have to do in the SSC, but i don?t know what. If i understand it correctly, i should adjust ArgOfPericenter and MeanLongitude? But to what?

Thank you for the support, all of you.

BTW: the Add-on, without the XYZ is posted on my website now. I hope to have a revised version up later, if i can get this done. In the existing version, i have managed to put it in an orbit that takes it close to Earth every two years, and close to Saturn and Jupiter every century or so... But Venus was impossible.

Comments and criticism are welcome.

-rthorvald

[jestr]

Runar,what time of day does the comet hit Gibralter?Jestr

[rthorvald]

Runar,what time of day does the comet hit Gibralter?

Gregorian: january 01, 1878 at 2 hours 47 minutes 35,6 seconds past midnight.
Julian: 2406985.61639

All the numbers are listed in the first post in this thread, but i noticed i haven?t listed gregorian dates here - only in the attached Verne text file.

-rthorvald

[jestr]

Looking at the positions of the planets in 1878 I think it makes a lot more sense to change the perihelion of Gallia putting it after the closest approach to Venus ,otherwise the orbit of Gallia will have to loop back on itself in order to go past Jupiter and Saturn as shown below

I know it is all fantasy but this small change could make the orbit look a little more realistic.

I guess Jules Verne didnt have Celestia installed on his computer,let me know what you think,Jestr

[Jeam Tag]

I guess Jules Verne didnt have Celestia installed on his computer,let me know what you think,Jestr

Great Idea Runar, I do not remember very well 'Hector Servadac' (read when I was teenager) but your creation looks very, very nice. This is this poetry that I love to find in Celestia, like the marvelous worlds by Rass, and so on. Thanks, Jeam

[rthorvald]

Looking at the positions of the planets in 1878 I think it makes a lot more sense to change the perihelion of Gallia putting it after the closest approach to Venus ,otherwise the orbit of Gallia will have to loop back on itself in order to go past Jupiter and Saturn [...]

Thanks, Jestr, for this observation; i will make the change.
Getting the spirit of the story right is what is important; i am using the data as a guideline, but it does not always add up.

Now, if only someone could tell me how to get XYZ data for space coordinates that does not have names in the NASA database...

-rthorvald

[jestr]

Hi Runar I have most of this orbit done now,still a bit of tweaking to do though but the Aphelion distance makes no sense at all (I calculate it should be inside the orbit of Saturn ) where do you think it should go-somewhere between Saturn and Uranus perhaps,it is only a months travelling from Saturn to Aphelion,Jestr

[Jeam Tag]

Verne included lots of data on the orbit. If it is of any use, I have collected it here: http://runar.thorvaldsen.net/celestia/temp/vernedata.txt

Hi Runar, I've read your abstract of the book only wrote in French: the Verne's notations of distances are in "lieues' (l.), an ancient mesurement: French Miles. But I don't know the one it was used, I found 3 references:
'Lieue de Paris' or 'petite Lieue' or Lieue de poste' = 3,898 meters
'lieue commune' = 4, 443 meters
'lieue marine' = 5,556 meters.
As I can Understand, Notations are the distance from the Sun ('Ab Sole') and the way traversed between 2 dates ('chemin parcouru')

Gallia
_Ab sole_, au 15 fev. 59,000,000 1. !
Chemin parcouru de janv. a fev. 82,000,000 1.

means: Feb. 15, Sol is 59,000,000 'lieues' away, and Gallia have traversed 82,000,000 "lieues" on its orbit during january.
If it can help, Jeam

[rthorvald]

Hi Runar I have most of this orbit done

Jestr, this is fantastic news! Thank you

the Aphelion distance makes no sense at all (I calculate it should be inside the orbit of Saturn ) where do you think it should go

This is Verne?s data:

"No!" said Procope; "the orbit of Saturn is remote, and does
not come athwart our path'"

Time: 1878:15:12
Julian: 2407333.5
Distance from the Sun: 1330000000 km
Closest approach to Saturn: 668000000 km

Time: 1879:15:01
Julian: 2407364.5
Aphelion.
Distance from the Sun: 1100000000 km

...

At re-reading the chapter about Saturn, it seems i have missed this earlier: Gallia?s aphelion is indeed inside the orbit of Saturn.

I suggest that we keep it that way, if practical - but at the same time gets the comet as close to the planet as possible; elsewhere in the text, Verne describes Saturn as the prominent object in the sky; the discussion of it is an event in the story.

But this is what would be optimal; if impractical, make it the way that seems correct to you.

Again, thank you for the work!

-rthorvald

[jestr]

No problem I can put Saturn as close as you want to Saturn but then the Aphelion will be very close to the orbit of Saturn,Jestr

[rthorvald]

Verne's notations of distances are in "lieues' (l.) [...] As I can Understand, Notations are the distance from the Sun ('Ab Sole') and the way traversed between 2 dates

Thanks, Jeam Tag. I think this is repeated in english miles and leagues, which i used a web calculator to convert to kilometres.

What Jestr just wrote seems to affirm this data /conversion is correct (he used it, and spotted an error in my notes).

-rthorvald

[rthorvald]

No problem I can put Saturn as close as you want to Saturn but then the Aphelion will be very close to the orbit of Saturn,Jestr

Well, a little artistic freedom here, then...
In the story, Jupiter is _the_ major event. Saturn is more remote, but still something that is noticeable. That?s what i would like to recreate; Saturn ought to be recognizable from Gallia?s surface, but not filling the sky.

-rthorvald

[jestr]

Runar does it say where in the med Gallia was over at 02:47:36 on 01/01/1880,Jestr

[rthorvald]

Runar does it say where in the med Gallia was over at 02:47:36 on 01/01/1880,Jestr

Almost directly above Mostaganem, which is a city to the east on the Algerian coastline.

-rthorvald

[Jeam Tag]

At re-reading the chapter about Saturn, it seems i have missed this earlier: Gallia?s aphelion is indeed inside the orbit of Saturn.-rthorvald

Yes, and it is said that the orbit of the comet was modified by the Earth encounter to a simple elliptic one in the Earth Orbitic Plan, inside the Saturn orbit, 2 years period...but of course, the second Earth encounter will turn this calcution wrong, and the comet left off.... Jeam

[rthorvald]

the orbit of the comet was modified by the Earth encounter to a simple elliptic one in the Earth Orbitic Plan, inside the Saturn orbit, 2 years period...but of course, the second Earth encounter will turn this calcution wrong, and the comet left off.... Jeam

You?re right. It came originally from outside; the mad scientist discovered it in the constellation of Gemini, and it was a parabola until it hit the Earth.

The ellipse was to take it to a second head-on collision with the Earth two years later, but the orbit was modified by two things:
- it picked up a satellite in the asteroid belt after perihelion
- Gallia broke in two, and lost the Island of Gibraltar right before the second encounter.

I omitted this from the Verne data not to overly complicate things, but maybe i should not have? Was tempted to treat Gallia and Gibraltar as two separate objects from the start, but since i don?t know the first thing about orbital mechanics, i was not sure i could pull it off. It would have been fun, though: (wandering off-topic: the englishmen at Gibraltar refuses to leave, and i have a dim recollection of a reference to them in a different Verne story, where they are observed by an astronomer two years AFTER Gallia?s second encounter... Wawing like mad, as Gibraltar zips past the earth!!

-rthorvald