Old Pictures from Celestia (locked)

[fsgregs]

Reiko:

Really nice spacedock and starship. You are a gifted designer. What starship is that??

Frank

[ajtribick]

What's going on here then? Add-on coming soon...

[ElChristou]

What's going on here then? Add-on coming soon...

Interesting!

[Reiko]

Reiko:

Really nice spacedock and starship. You are a gifted designer. What starship is that??

Frank

Thanks but I didn't design it. It's the same type of ship Khan had in the 2nd Star Trek movie. This one will be called the USS Azumi.

[Reiko]

What's going on here then? Add-on coming soon...

Very nice! I have this space art book that features W UMa.

[bdm]

What's going on here then? Add-on coming soon...

W UMa is the prototype for a class of eclipsing variable stars that are contact binaries. I look forward to seeing this addon when it comes out.

[ajtribick]

And some more...

[ElChristou]

And some more...

These are models right? No real time merging,right?

[bdm]

I was going to make a similar addon for 44 Boo but couldn't find a good way of computing the Roche lobes for that star so I didn't try. Imagine what it would be like if you lived on a planet orbiting a star like this.

[ajtribick]

Yes they are models... this is why I've been asking about the cmod tools elsewhere on this board. They are generated using a Perl script, but the algorithm I'm using to find the surface isn't particularly robust when the fill-out factor gets close to 100%, i.e. when the equipotential gets close to the L2 point. (Incidentally, 44 Bootis is the case where the fill-out factor is 0%, i.e. the two stars just touch at L1... though this is somewhat suspect because the presence of the bright tertiary star in this system makes the measurements rather difficult!) The algorithm works for all the cases that are in the add-on, but I'd rather create something a bit better before I release it. Also it could run a few times faster by taking advantage of the symmetries of the systems.

Edited to add: I have started a thread on the Celestial Matters forums about this add-on.

[Royofsaltfleet]

New Africa - Epsilon Indi A
February 16th 2333

New Africa Orbits Savannah, a Saturnian type world. Locked in at the L1 point is the small world of Lee, a permanent feature in the day sky of New Africa. It is always Occulting Epsilon Indi A

New Africa supports a Bio diverse ecosphere similar to earth in the Pre Tertiary Period, animal life is abound but primitive, Terran Life can still survive in the harsh conditions
Lee by contrast is an even more primitive world, analogous to a warm titan or very early earth, the atmosphere is chokingly primitive. however the high surface pressure has retained liquid water and a steamy swamp like ecosystem has developed, insect life is abound but it is mostly undeveloped and very primitive, Earth like life forms have to be isolated from the environment, except for primitive plant species, they thrive in the misty high CO2 atmosphere

Savannah.jpg

Lee and Epsilon Indi.jpg

Lee and Savannah.jpg

[Reiko]

New Africa - Epsilon Indi A
February 16th 2333

New Africa Orbits Savannah, a Saturnian type world. Locked in at the L1 point is the small world of Lee, a permanent feature in the day sky of New Africa. It is always Occulting Epsilon Indi A

New Africa supports a Bio diverse ecosphere similar to earth in the Pre Tertiary Period, animal life is abound but primitive, Terran Life can still survive in the harsh conditions
Lee by contrast is an even more primitive world, analogous to a warm titan or very early earth, the atmosphere is chokingly primitive. however the high surface pressure has retained liquid water and a steamy swamp like ecosystem has developed, insect life is abound but it is mostly undeveloped and very primitive, Earth like life forms have to be isolated from the environment, except for primitive plant species, they thrive in the misty high CO2 atmosphere

Savannah.jpg

Lee and Epsilon Indi.jpg

Lee and Savannah.jpg

You have some great stuff here. You going to be uploading any of it?

[Hungry4info]

And some more...

Yeah I'm not going to lie, those are very awesome.

How are you accomplishing it? Is there a model for each system? Or have you modded Celestia to actually allow contact binaries to be rendered, just given some parameters?

[Royofsaltfleet]

You have some great stuff here. You going to be uploading any of it?

Probably not, i havent got the skill to create my own textures yet (working on it) so i just mish mash ones ive found together.

When i get the neccercary artist skills (or find enough money to pay my tallented brother:) )
i may redo the textures and release. They are however all part of a Sci Fi universe i am developing to accompany several books i'm writing/written

im trying to get a couple of stories together to release Galactic North Style

[ajtribick]

How are you accomplishing it? Is there a model for each system? Or have you modded Celestia to actually allow contact binaries to be rendered, just given some parameters?

Yes it's a model for each system, automatically generated by script. I'd like to get it supported directly by Celestia eventually (this is the reason I am working on improving the generation code before I release the add-on, in order to have a working algorithm to implement in C++), but firstly I don't know enough OpenGL, and secondly I would want Celestia to have support for units in catalogue files first. I don't see the latter happening until after the 1.6.0 release.

[chris]

How are you accomplishing it? Is there a model for each system? Or have you modded Celestia to actually allow contact binaries to be rendered, just given some parameters?

Yes it's a model for each system, automatically generated by script. I'd like to get it supported directly by Celestia eventually (this is the reason I am working on improving the generation code before I release the add-on, in order to have a working algorithm to implement in C++), but firstly I don't know enough OpenGL, and secondly I would want Celestia to have support for units in catalogue files first. I don't see the latter happening until after the 1.6.0 release.

Direct support for generating the models from parameters would be a welcome addition to Celestia. No actual OpenGL programming should be required: the C++ code could just generate an instance of the Model class. It would be very similar to what your program is doing now, except that you'd create the model in memory rather than writing it to an ASCII stream.

Are units absolutely essential before proceeding? I can see where the choice of parameters for specifying the shapes might make having units very useful. For example, masses in astronomy cover such a huge range that it's impractical to always use a single default unit type.

--Chris

[ajtribick]

I'd say yes units are necessary. The semimajor axis and orbital periods of these systems are more naturally expressed in solar radii and days/hours than AU and years, which are the default units in .stc files. I get round this in the add-on by using radius (which is in km) and rotation period (hours), but these aren't really the best names for the properties (and because of all the fun of the automatic mesh centring the radius value isn't a particularly obvious quantity for the end-user). I would also be unwilling to see another context in Celestia catalogue files with its own set of defaults for the units.

Also is it just me, or is it the case that the rotation axis is the z-axis for models in .ssc files, and the y-axis for .stc models?

[Royofsaltfleet]

Deimos/Tranquillity - 61 Ursae Majoris
March 6th 3040

Tranquillity is an earth sized moon of a gas giant world called Deimos. Tranquillity orbits Deimos in little over 2 weeks and takes 32 hours to spin on its axis. Its orbital inclination means it is only in eclipse twice in Deimos’ 272 days. While tranquillity’s orbit about Deimos is circular and stable, Deimos’ orbit around 61 Ursae Majoris is quite eccentric meaning that the distance between Perihelion and Aphelion is a little over a tenth of an AU (9.2 million miles) this creates huge seasonal variations meaning that tranquillity’s weather gets quite violent at perihelion. The high water content and the radiation flux received from Deimos means that the atmosphere is very overcast and is almost covered in 80-90% cloud cover. The world itself is about as old as earth geologically and has several small continents that are far apart fuelling the storms. The world is not very mountainous, most of which are extinct volcanoes Life has developed a hardy relationship with the weather on this planet, huge trees grow with internal structures similar to birds wings, they are permeated to allow the pressure differences to dissipate. The internal shapes of the permeations are also spiralled in the opposite way the usual storm rotations meaning that they dissipate hurricanes better. Other life on this world almost always takes up residence in one of these trees.

Deimos has a layer of atmosphere about 100 miles thick where the gas mixture and pressure is breathable. The temperature at this depth is about 50oC making it on the warm side. There are unpleasant noxious gasses at this level though but the gas concentration is not fatal, but still unpleasant to breathe unaided. This level is populated by SkyDocks, dirigible cities and Skymines. Life on Deimos is rife and exclusively avian. The upper biosphere is largely responsible for giving Deimos its greenish Brown Colour. There are at least 3 belts where completely separate ecosystems have developed each one with completely incompatible biochemistry, indeed there is thought that a 4th ecosystem exists deep in the Metallic Hydrogen Layer 60,000 Km deep. The Biomass of all 3 known ecosystem belts is believed to be 10 times the Biomass of all known planets that have independently developed life (Circa 3040) a huge amount as nearly a hundred worlds are known.

Tranquility and Deimos.jpg

[bdm]

Like Royofsaltfleet, I have been creating some fictional planetary systems around real stars. Here are a few planets that I created:

61 Virginis
Explored by probes for the first time in 2930

Ferrugo
Ferrugo is a Marslike world orbiting close to its sun. Its rotation is tidelocked and much of its original atmosphere has frozen out into an icecap on its dark side.

ferrugo-1.jpg

Levitas
Levitas is a gas giant of about 30 Earth masses with a broad but relatively faint ring system. What titanic event in its early history caused it to be tilted on its side?

levitas-1.jpg

Ovatus
Ovatus gets its name for its shape. Its rapid rotation (about 7 hours) gives it a noticeable flattening at the poles.

ovatus-1.jpg

[bdm]

Deimos/Tranquillity - 61 Ursae Majoris
March 6th 3040

Tranquillity is an earth sized moon of a gas giant world called Deimos. Tranquillity orbits Deimos in little over 2 weeks and takes 32 hours to spin on its axis. Its orbital inclination means it is only in eclipse twice in Deimos’ 272 days. (snip) The world itself is about as old as earth geologically and has several small continents that are far apart fuelling the storms.

A few notes regarding secular changes of such a planet are in order here.

Firstly, a world with an age of a few billion years orbiting a gas giant at this distance is very likely to be tidally locked to that planet. See Titan for an example. A habitable world like this in a circular orbit about its primary with a day of 32 hours would either have a 32-hour orbit, or orbit so far from its parent gas giant that its orbit would be destabilised by other planets in that system.

Secondly, inclined orbits have stability issues, in that inclination gets traded for eccentricity on geologically short time scales due to the influence of the equatorial bulge of the planet. Inclined, circular orbits get converted into eccentric equatorial orbits, and this can cause the moon to smash into another moon (a possible cause for Saturn's rings, perhaps?) or even smash into the planet. This is why planets in the solar system have no known natural satellites in polar orbits. An alternative way of engineering infrequent eclipses is to give the primary a suitably large axial tilt.