Celestia Forums

...They have the longitude origin at the edge, so you'll have to perform the familiar offset-by-50% in order to make them match Celestia's convention, or modify solarsys.ssc appropriately. Also, the Iapetus one is actually 2k. I imagine that with the texture data we've got now, much higher-resolutio...

Steve Albers has 1k Titan and Iapetus textures that incorporate Cassini data! The Iapetus one doesn't include the New Year's flyby yet, but it's got information from earlier Cassini photos (and you can actually faintly see the west end of the equatorial ridge). The Titan one includes relatively hig...

Actually, there are occasional "lapses" in their updates. I've noted the same thing at the Cassini site. There will be several days with nothing new, and then suddenly those several days are posted in a rush. Rather than conspiracies, I think it is more likely that the people responsible for the up...

The sky (Ozone in particular) gives that blue color to oceans. When the sky is grey, the sea looks all grey too... First, I don't think ozone in particular has much to do with it. Rayleigh scattering can be performed by anything with an electric dipole moment. Second, while you're mostly seeing ref...

Well, it's not going to hit us in 2029, but it will certainly be an impressive close encounter. Sadly, when I was trying to figure out what the effect of a collision would be, I came to the conclusion that the real earthquake and tsunamis on Dec. 26 were probably worse. If you want to know what it w...

There are two different definitions of mass that are sometimes used in the context of relativity. One of them is the so-called "relativistic mass" which is just the total energy of an object divided by c^2. This increases with velocity for ordinary objects (though the increase is tiny for speeds tha...

JDicus wrote:Santa didn't bring me a new Video Card so I must resize.
I resized the Billboards to 1k, I assume no settings need to be changed to have them appear the right size.

That's right, as long as you size them to dimensions that are a power of 2 you should be fine.

I've got a 2002 G4 Mac with an old Radeon 7500; in recent Celestia versions I can see the shadow of the rings on Saturn, but not the shadow of Saturn on the rings (though, oddly, once or twice I've seen a crude, blocky version of about half of the shadow-- it's a non-reproducible event). I think it'...

Hehe :D This is my version of the mosaic. ;-) Nice one! This is the first version I've seen that mosaiced the whole disk as UV/green/IR color. (They actually took visible-light RGB exposures of all these pictures too. Out of curiosity I tried making a close-to-true-color picture of one of the shots...

Matt McIrvin wrote:http://spaceflightnow.com/news/n0411/10uranusweather/

...actually these are from Keck, not Hubble.

It's springtime in Uranus, and the atmosphere is getting more active. Recent Hubble observations show some clouds (cirrus?) on Uranus. So it may just have been a very dull time at the time of Voyager 2 flyby. But of course it is never as featured as Jupiter or Saturn. Those recent pictures make Ura...

Here's a mosaic of the most recent Cassini raw images showing the whole illuminated disk: http://world.std.com/~mmcirvin/iapetus_mosaic.jpg I'm no geologist, but in appearance, the spine reminds me of nothing so much as Earth's mid-ocean ridges, which come from sea-floor spreading at plate boundarie...

You know, they used to say that NOTHING could travel faster than the Sound Barrier too. I'm waiting for more information... Actually, nobody ever said this; the sound barrier was known to be an engineering problem specific to airplanes, not an absolute physical limit. Rifle bullets were well-known ...

Now, that said, the difficulties involved are real and the color information in Celestia textures does vary in quality. It's gotten better over time as the many contributors to Celestia refine their work and incorporate new information. Voyager photos released in the 1970s and 1980s often had inaccu...

Apparently displaying color as a human would see it is non-trivial. I just read an article that says all the images from Spirit and Opportunity are way too red. Mars is the ochre planet, not the red planet. And they even have RBG filters available. But to accomplish the most with the least bandwidt...

There are slightly better raw images now, from which I made a false-color picture (IR/green/UV):



But I'm sure I'm only half a step ahead of the pros...

Yes, I'd be inclined to wait until the people who do this stuff for a living put out a map. They've got the best software, the best data and the best knowledge about how to put it all together. (In the meantime, the Planetary Society Saturn site has Voyager-based photomosaics that are interesting al...

Brendan wrote:I use 3ds models for Mimas and Tethys. Whoever made those should make one for Iapetus when the data is available. 8O

Brendan

That might be a long time in coming! Personally, I'd be satisfied by a higher-resolution map. But moon cartography takes time...

Assuming that the planet loses nothing but its atmosphere, and that the atmosphere was uniformly thick, there wouldn't be any change at all in the gravity at the surface. The mass of the atmosphere would have pulled on objects above it in space, though, so that force would diminish slightly because ...

I also found this very nice 1939 Astounding Science Fiction cover showing a view of Saturn from Iapetus (I can't find the name of the collector, unfortunately). The artist, Charles Schneeman, really did his homework-- I'd say it stands up pretty well even today! The foreground landscape seems a subt...