Celestia Forums

Hey everyone. I just started using Celestia recently, and just love it; so, in the spirit of Open Source software, I worked on it a bit and added in some new informative capabilities (and put in the data that I could track down on the subject, along with formulas to approximate the information in its absence). The new information that shows up in verbose mode:

Moons and planets:
Surface temperature fields (mean, day and night averages, seasonal averages, planetary extremes) (K); mass (kg); atmospheric pressure (Atm); if they have an atmosphere, its contents and percentages (by volume).

Spaceships:
Mass (kg); Internal temperature (K)

Stars:
Mass (kg); Lifetime (years)

Masses are internally stored in metric teratons so as to roughly center the decimal place between working with small objects like starships and large objects like planets. Masses of most solid objects that aren't known (such as many of the asteroids and some of the minor moons) are approximated by a formula using 10*(radius^3.1), which seems to generally hit pretty close to the mark.

The temperature fields follow a more complicated formula when they're not known; it takes the default distance/albedo code, and factors in the atmospheric pressure to get the mean temperature. The day/night local temperatures are based on the mean, adjusted by how fast the planet rotates and the atmospheric pressure. The seasonal temperatures are based on the daily temperatures adjusted by the tilt, atmosphere, and year length. The global extremes are based on the seasonal extremes adjusted by the size of the object. I adjusted all of these formulas to try and get four bodies for which I know temperatures pretty well (Mercury, Venus, Earth, and the Moon) to match up with their actuals; it seems to get pretty reasonable values for other planets and moons as well. A new field - pressure - was added to the atmosphere section.

For all star fields, I added in some new lookup tables that are similar in structure to the current temperature lookup table.

For adding support for gasses, there are new fields that can be added into the atmosphere section (correspondingly, for the gas giants, I had to add an atmosphere section). These are GasNameX and GasPercentX where X is an integer from 1 to 10 (thus, you can have up to 10 gasses listed; you don't have to fill them all). If your gas percents don't add up to 100%, don't worry, it'll equalize it to 100 for you. The gas names are stored as their chemical formulae, for brevity. All of the information that I listed is accurate, although the percentages may be a little off on some of the trace elements of the outer gas giants, since those numbers were hard to come by.

I'm going to try to track down who to send the patch to... if anyone reads this and knows, let me know and I'll send it. On to my next project: enabling a new class of object that, now that we have masses, can "free-float" around, being tugged on by the gravity of the N nearest/heaviest objects. Naturally, we'll want to keep the number of objects like this to a minimum, as they'll actually use CPU even when you're not near them; hopefully, I'll be able to come up with a way to detect if they've entered a roughly stable orbit, calculate that orbit, and set them to it, thus making them a standard, low-cpu object until something changes again. Regardless, if I can get this to work right, we should be able to model things like gravity assists and simulate spacecraft trips.

Rei:

you make me curious: what does the website you quote have to do with you? Are you

FEMALE??



No, this cannot be! Celestia herself is female, a beautiful 'lady', indeed, and unfortunately tends to attract only men...

Byebye

Fridger

PS: Concerning your patch, it would perhaps be not bad to first get to know Celestia and her design principles a little better before starting to modify her right away;-)

t00fri wrote:PS: Concerning your patch, it would perhaps be not bad to first get to know Celestia and her design principles a little better before starting to modify her right away;-)

Ahh, but this is as if going shopping with your new friend (just arrived at your city), and select a dress (or jacket, or something else) for her...


Don't be so upset by the changes, Fridger; that's what the GPL allows. Accepting the changes in the main branch is another thing, though...

jamarsa wrote:Don't be so upset by the changes, Fridger; that's what the GPL allows. Accepting the changes in the main branch is another thing, though...

Come on;-) I am not at all upset! I am delighted by the chances to meet a fast programming lady in this forum....

Ahh, but this is as if going shopping with your new friend (just arrived at your city), and select a dress (or jacket, or something else) for her...

Good comparison;-). As concenrs myself, I would certainly first try to get to know that "new friend" a little better before buying a dress (or jacket, or something else) for her...

Bye Fridger

hehe, yeah (and I hate that picture, but it's one of the only ones that I had available when I put my council site up...).

If you don't want the additional information in Celestia, that's fine, although I personally think it looks pretty dern neat being able to get all sorts of information about a planet in verbose mode I was actually quite surprised to see that they didn't already have things like mass stored (but, on the other hand, were already computing star surface temperature and things like that).

At the very least, I'll keep the patch for myself. I just figured, I better get to programming while it's still a "new toy", so to speak.

Rei wrote:hehe, yeah (and I hate that picture, but it's one of the only ones that I had available when I put my council site up...).

Honestly, this is a very good one! You are for sure going to win the competition;-).

Actually, since more than a decade, I have a good internet 'friend' in Iowa City (Elwood Downey, the author of XEphem...), whom I never met in person, while I have flown many times over his head;-). So please say hello to him, when you happen to meet him in the streets...

And now let me "proudly" announce that the Celestia forum hosts already 2 women among 842 registered users: LadyHawke and Rei!

Bye Fridger

Rei wrote:I'm going to try to track down who to send the patch to... if anyone reads this and knows, let me know and I'll send it.

whell I read it, and I think I have an idea of who. You should probably send it to chris, and if he likes it, he can distribute it with the basic celestia package. If not, then I'm not sure.

Welcome Rei,
I'm interested in having a look at your work. Could you email me the patch?
I've added a star mass lookup table as well but it is very rough and needs some improvement.

thanks.
marc.griffith@iinet.net.au

t00fri wrote:And now let me "proudly" announce that the Celestia forum hosts already 2 women among 842 registered users: LadyHawke and Rei!

Are you serious? That's kind of scary, really.

Are there that few women who think astronomy is neat? Or is it the combination of astronomy and programming that is the problem?

Blah.

guest wrote:
Are there that few women who think astronomy is neat? Or is it the combination of astronomy and programming that is the problem?

Blah.

My guess is that there are more women. Unless someone specifically identifies one's self as female I think most of the forum users assume they are male.

If you want to get more women interested in astronomy then add astrology to the keywords searched for. It sounds sexist but it isn't. I didn't look for astronomy packages on the net when I came across this site, I found this site over a year ago attempting to find a good electronics simulation package. It got me interested in astronomy again and I've never looked back. Another point, identifying yourself as a female on a predominantly male site can easily draw unwanted attention to your gender rather than your contribution to the forum. Perfect example: this thread.

Having said that, I like the idea of extra information in verbose mode. Visually celestia is nothing short of stunning, expecialy with some of the great add on textures but it could be more stimulating for the mind too.
Any idea that promotes this has my vote.

For example, if I'm looking at a new add on nebula wouldn't it be great if I could get some background information on it as well as see it. It's age, size, theory of formation, when and who discovered it anything that stands out to make it unique or interesting to astonomers. Please note I'm not taking anything away from the developers of these beautiful images. But the time required to provide a little background information on the object can't be that much compared to the time it takes to create it. Neither are the memory requirements large for a text description compared to the size of the image.



Regards,

Another point, identifying yourself as a female on a predominantly male site can easily draw unwanted attention to your gender rather than your contribution to the forum. Perfect example: this thread.

This is merely a symptom of the unusual - a male user on a predominantly female site would surely ellicit similar responses. If the proportion increased then it would become mudane and commonplace and nobody would mention it anymore.

Cheers,
Paul

This is more like a woman walking through a construction site.

I would have figured that this thread would be about development issues or issues related to the patch.

I never should have put a URL in my info section.

Rei wrote:I would have figured that this thread would be about development issues or issues related to the patch.

I never should have put a URL in my info section.

Rei:

You are entirely right. It's my fault. Can you send me your patch? Chris is also working on it, I am told by a little birdie...

Here's a little personal info, just for you:

---------------------------
My life was very much influenced by professional women. My wife is a theoretical physics prof., too, and my daughter is just becoming a theoretical physicist...

In short, I am usually getting carried away when I meet women where I can feel they are striving for some kind of challenge...whatever it is. I simply was impressed by your WEBsite.
-----------------------------

Bye Fridger

t00fri wrote:You are entirely right. It's my fault. Can you send me your patch? Chris is also working on it, I am told by a little birdie...

That's a relief!! For a moment, I thought this thread was heading direct to the purgatory...
and that would be a shame.

Wellcome Rei

I'm glad that you are working on one of the feature that is in my personal request list: More infos about objects.
See group 7 at http://members.xoom.virgilio.it/pangeli70/My%20celestia.htm.

I hope that your contribute will be integrated soon in one of the next versions of Celestia.

Bye - Paolo.

Refreshing to see others working on the source...specially issues I like to see developed...

Welcome Rei...I pmed info where you can send your patch...thx

Paolo -

The project that I have planned aft er the current one that I'm working on (free-floating bodies) is part of one that's also on your list. I've written a really nice looking terrain generator before, and I plan to adapt it to Celestia planet surfaces, using the "known" points from tbe bump as a baseline for heght data, the specular map for knowing where water (or other liquids) are, and an estimation from the bump map and the color map for what sort of vegetation/rock formations/etc to put in for a given area. I'll be sure, when I get to doing that task, to be sure to leave the option for "blow-up" region maps to be put in, where the area has a much higher known height-map and color-map resolution than the overall planetary map, thus making more "real' visual data. If someone wants to write a city generator or a the ability to go to a city by typing it in, that would merge just great with it.

I think it would be so neat to be able to watch the stars from Mt. Everest, or watch the sun rise over Olympus Mons... (etc). If people are feeling itchy to code, there's huge potential for expansion, such as modelling Io's volcanoes so people can watch Loki's eruption cloud out Jupiter, and slowly rain down, or flowing rivers of Ethane on Titan under a light hydrocarbon mist-storm... (etc).

I'll probably only get to implementing the basics. It'll probably be a few weeks before I'd get to starting on this project, as I'm still improving the infopatch based on suggestions from the developers, and working on the free-floating object modelling.

Paolo wrote:Wellcome Rei

I'm glad that you are working on one of the feature that is in my personal request list: More infos about objects.
See group 7 at http://members.xoom.virgilio.it/pangeli70/My%20celestia.htm.

I hope that your contribute will be integrated soon in one of the next versions of Celestia.

Bye - Paolo.

Rei, Paulo:

Paulo, I could not check your URL above since it does not work....

BUT in fact:

Celestia already makes available a wealth of most reliable data about any kind of objects upon a simple click on the object! It uses the WEB-browser as the /appropriate/ interface. Most help facilities of software applications nowadays use WEB-browsers, too. This 'info philosophy' also is beautifully in line with Celestia's unique cel://url feature!

A number of people simply may not have correctly installed this or do not seem to know about this existing great info feature in Celestia.

The present approach of using professionally authorized "world data" like from the Simbad data base or from nineplanets.org via a Web browser is most elegant, up to professional standards, most complete and will be automatically updated by "them" rather
than by us.

This is much preferable to Rei's
philosophy of hardcoding extensive info data about celestial bodies into Celestia's core, like tables with gas compositions etc.

I think, we should tend to only display that info on the main canvas that /is somehow used/ by Celestia to define the actual configuration; or info that /directly/ exists in the database Celestia uses for displaying a particular configuration, like spectral classes of displayed stars, etc.

In this spirit, it is urgently needed to display the cursor readouts (on demand) corresponding to the various coordinate systems Celestia may use. Like (lat,long), (RA,DEC), (ALT, AZ), ecliptic, galactic....
For that reason, too, it is important not to make the display of the main canvas too crowded.

Any further info should finally come from a standardized, professionally approved data base via the usual WEB-interface.

All astronomers worldwide take Simbad as a reference data base. It is wise policy, if Celestia does so, too....

Bye Fridger

Fridger:

Here's a google image search for "celestia"

http://images.google.com/images?q=celes ... 59-1&hl=en

Notice that almost all of the images that haven't been cropped not only have information on, but have verbose information on. People like this feature. You don't take out/weaken features that people like with software, that's generally a bad design philosophy.

It's not a lack of knowing about the URL feature, it's that people want to use Celestia, not a web browser. If they wanted to use a web browser, they'd pull up a web browser and go straight to what they wanted. Often times, websites are slow (last night, I couldn't connect to nineplanets at all). They block your screen, which would otherwise be filled with beautiful Celestia views. They're inconvenient. There are dozens of reasons why that wouldn't be wanted.

Also, displaying Celestia's internal information will be misleading to people. For example, consider the radius. What radius does it report for, say, Amalthea? Amalthea is not a sphere. Talking with people, I've determined that Celestia is supposed to use the maximum radius. How do people know this? Minormoons.ssc, a popular addon, uses the average. If people interpret the radius of Amalthea as being real, it'll give a volume over 3 times higher than its real volume. BTW, any clue why the radii on solarsys.ssc are all smaller than those that NASA lists as the maximum, except for one which is larger than the max? In my last mail to Chris, I suggested that I make it so that we store the 3 axes' max dimensions, and then have getRadius return the max, and a new function - getRadii - return values for all of them, so that we can display all of them.

Finally, my infopatch corrects much of the information that was already on there inaccurately, such as planet temperatures (how hot did it say Venus was, for example?). Of course, you want to remove this information altogether, and make people use your preferred method for getting information.

I would welcome discussion of how to indicate how accurate the reported numbers (and the mesh and surface texture as well) are, and I would welcome discussion about how to make the approximation formulae as accurate as possible, but I just think that taking out a quite popular feature is a Bad Idea(tm). Just my two cents.

For example, would you like to join in our conversation about how, given the mass, orbit, and star details of an extrasolar planet, to get as realistic of a radius as possible, since the current gas giant formula doesn't accurately represent large gas giants or those in orbits close to stars? My last proposed formula was to use the distance from the star and its luminosity to approximate how much radiation the giant is getting, and use that as a logarithmic scalar (since heat can "inflate" gas giants) to a formula that approaches a radius of 80,000km as the mass of the gas giant approaches infinity. The whole formula would be curve-fit to match our solar system's giants and the known extrasolar radii. Certainly, without knowing how oblate the planet is, what it's chemical composition is like, and other factors, there's no way that we can be perfect. But we can do our best to be as close as possible, now can't we?

I would think that, given your background, you could contribute greatly to such a discussion.

I'll add that it's quite discouraging to see such controversy over enhancing a feature that is quite popular. I could understand someone not wanting to incorporate a patch for something like gravitational modelling into the main branch, but such a controversy over additional information is beyond me - and really is discouraging to development. I mean, if you're so adverse to this, what could I expect from, say, making realistic planet surfaces or almost anything else that I could contribute?

BTW, I think it is good that we're moving this back to the board instead of via email, so that others can take part in the discussion.