Celestia Forums

Here is a relevant part of the Usenet Physics FAQ: http://math.ucr.edu/home/baez/physics/Relativity/SpeedOfLight/FTL.html There are various things (such as, say, the position of a rotating searchlight beam) that can go faster than light without violating relativity. What these things have in common ...

From CARTOGRAPHY OF THE ICY SATURNIAN SATELLITES : ... This very interesting report includes a map showing the coverage of Dione at various resolutions expected to be obtained by Cassini in 2004-7. Thanks! That paper is fascinating. And now I'm thinking that the caption on that JPL map was complete...

Here is a raw picture from two days ago that I enhanced a bit: http://world.std.com/~mmcirvin/iapetus_seam.jpg It looks as if that line of gigantic mountains just keeps running along the equator, right across the dark oval. Look at how tall they are on the horizon! I'm looking forward to the next fe...

There's a huge argument about this going on over on the Bad Astronomy board; lots of people seem to think it can't be a tectonic fault because it's perpendicular to all the giant cliffs. But that sort of thing happens on Earth as well, doesn't it? At least, I have dim recollections of National Geogr...

...On the other hand, come to think of it, I've noticed that in the Celestia orbit Cassini passes much further from Iapetus around Dec. 31/Jan. 1 than mission descriptions say it will. So there may be more to it than that.

The thread on the Titan-B flyby mentioned that Celestia had it occurring at about 1800 km distance, whereas the real distance was more like 1200 km. That makes me think that the relevant change might have been the correction mentioned here, designed to improve the margin for error in Iapetus's effec...

I remember reading the Scientific American book adapted from Charles and Ray Eames' "Powers of Ten" films , and noticing that the pictures ran out at 10^-18 m (distances covered by quarks dancing inside a proton) on the small side, but went up to something like 10^25 m on the large side (a billion l...

It sure looks as if Cassini and Gemini are seeing the same phenomenon, whatever it is.

Fridger, On the Cassini site there is a map of Dione showing the areas to be imaged during the recently flyby, based on more distant Cassini imaging obtained earlier in the mission. As far as I know, this earlier Cassini-based map of Dione has never been released publicly.[...] of course --being im...

Request for upright or altazimuth view mode:

http://shatters.net/forum/viewtopic.php?t=6361

(That was me, in case you were wondering. Forgot to log in.)

There's a weird, persistent bug, seen by many people (with both ATI and NVIDIA cards, if I recall correctly), when running Mac Celestia with textures that are close to filling up the video card's memory: planetary textures appear blank or scrambled, and sometimes bits of the system desktop seem to b...

Hmm. Celestia does have the ability to perform the kind of display he wants for a natural satellite with a CustomOrbit (such as the Moon). Could there be any way to get a CustomOrbit for Mars Express in there?

The more interesting question is whether there would be a noticeable cast to the resulting illumination during "half-night" as opposed to during the day. A lightbulb filament looks white to me, too, but the illumination from a regular incandescent has a noticeable yellow cast compared to the illumi...

In addition, Alf Cen B is redder than Sol so would this colour difference be noticeable or would the retinas be saturated and the difference not noticed? We'd see it as white. We see any bright continuous spectrum as white down to even red dwarf temperatures of 3000K ... that's the same temperature...

http://www.metaresearch.org/cosmology/speed_of_gravity.asp - "Conclusion: The speed of gravity is 2x1010 c" Over my head, but interesting.. Comments? I've gotten into arguments with that guy more than once. He's wrong. He's picked a strawman definition of "the speed of gravity" that is not useful. ...

The answer to my question must have something to do with grids. The available grids on my planetarium program are: galactic, ecliptic, RA/dec, Alt/Az. You want RA/dec. The celestial equator is at declination zero. In Celestia, the ; key turns on an RA/declination grid. Probably the best-known thing...

Adaptive label display might also work well with the big asteroid files, with a much fainter range of magnitude cutoffs.

Visual magnitude seems like an obvious analogue for the size/importance metric, for most purposes; in a sense this would be just like the current behavior except that the star's label and the star itself could have different display cutoffs. ...One possible exception is the case in which you zoom o...

Request for more flexible star label display:
http://www.shatters.net/forum/viewtopic.php?p=46260

As I said over on the Motherlode forum right before Shatters came up again, I've been idly speculating about the future of star labels. Right now, the stars that have displayed labels are statically coded in the main .cfg file, which is less flexible than it could be, and seems like a waste of all t...