First new AWoM wallpaper posted

[Lee Enfield-Burke]

Over at the YW website's wallpaper page, we've just posted the first of a new series of AWoM wallpapers which DD has been producing.

These are wallpaper-format images of material she used to help her "scout" locations for the book. They're made using the Terragen scenery-generation software which is used by many well-known film and TV production companies around the world (as well as countless gifted amateurs). DD plugged actual Martian laser altimetry and radar terrain data from NASA's Mars Global Surveyor probe into Terragen, and used it to produce first maps and then detailed "location photos" of places on Mars where key events in the narrative take place.

The first image is of dawn inside the northern-hemisphere crater Stokes, where Kit, Darryl and Ronan arrive together to quietly investigate some peculiar goings-on. Check it out:

Like all the other wallpapers to follow, this one is available in resolutions of 800x600, 1024x768, 1152x864, 1280x800, 1280x960, and 1280x1024. All these files are hosted at Box.net. (We're going to be moving all the other wallpapers there as well, to help save bandwidth and storage space in the main site.)

New wallpapers will be posted once or twice a week until the book's official release date on April 14.

By the way, for those of who who may notice that the old "Aram Chaos / Red Rede" wallpaper is missing: there's a much better version coming, which will be posted over the next few weeks.

[estar9821]

Not to be a nuisance, but I read that sunrises and sunsets on Mars are the opposite of those on Earth. That is, the sky is red and the sunset is blue. Otherwise, it's a beautiful picture.

[Diane Duane]

Lee passed this one along to me, and since I had a moment, I thought I'd drop in and comment.

Re "days are red, sunsets are blue" -- I read that too, but it looks like the truth may be a little more complex. (Ain't it always...)

First: bear in mind that we have exactly one sunset picture taken by a camera purposely adjusted to react something like the human eye (though even it exaggerates in some frequencies). The astronomers I talked to while I was working on AWoM suggested that there was probably a fair amoung of room for variation in sunsets, just as there is on Earth.

Next: the famous Gusev Blue Sunset picture here was taken on a day when there was a lot of dust in the upper atmosphere, producing an effect like the "volcano sunsets" we used to get in LA when there had been eruptions down in Mexico -- with a lot of scattering, a sun dimmed enough to look at with the naked eye, and a very prolonged twilight. Granted that Mars routinely has a lot more dust in the upper atmosphere than we would be used to, but there are also very clear periods outside the stormy seasons when there's much less of it hanging around up there. So at least some of those dawns and sunsets will look more like the Stokes render. This crater is away up north, far away from other areas where AWoM mentions that the recent weather's been dusty (as down in Syrtis Major where the wizards first inspect the "superegg").

Even in the Blue Sunset pic, though, note that things are going pink around the edges -- this bit being what often gets cropped out in media versions of the image. And the pink is even visible above the blue scattering over the sun. Are we seeing the super-prolonged Martian version of the "green flash" which a lot of non-astronomers now know about via the Pirates of the Caribbean movies?... We need more sunset pictures, is all I can say.

The commentary here also notes that Martian sunsets are likely to be "longer and redder" than their Earth counterparts, again because of the dust. Some of that is going to be because of high-level dust, but I didn't have that to work with here since I was keeping the dust in the Stokes render to a minimum. So I held the red haze effect down close to the crater rim, which blocks most of it from showing (and the effect also is slightly different from true sunrise because the genuine horizon is several degrees below the crater's rim. on the far side). The nearby landscape picks up some of that red via global illumination and some light from ambient occlusion.

Finally: yes, Martian sky is usually sort of butterscotchy-color in the daytime rather than blue -- or the blue is very paled and beiged-out. Later renders of other scenes will reflect this.

ETA: links where people are discussing Martian sky colors and whether or not the cameras do them justice:

http://rhinocrisy.org/2009/03/blue-sky-on-mars/ (at least these guys are fighting over the science and not the conspiracy theory)

http://en.allexperts.com/q/Astronomy...er-planets.htm (with a little discussion of Rayleigh scattering)

http://solar-system-astronomy.suite1...n_mars_is_pink (not so sure about the iron oxide end of this theory, must check)

http://www-mgcm.arc.nasa.gov/mgcm/HTML/FAQS/sky.html (discussion at NASA Ames site: role of magnetite scattering referenced here)

[Diane Duane]

More "Martian sky" links

Couldn't re-edit the last message for some reason. Fooey.

Meanwhile:

http://en.wikipedia.org/wiki/Astronomy_on_Mars (More sky pics to compare)

http://www.webexhibits.org/causesofcolor/14C.html (at Causes of Color)

[estar9821]

Wow. Thanks for all the links. I never knew there was that much controversy over the color of the Martian sky. People actually think NASA is covering up the fact that it's blue? Why would they? Ridicuolous.

And now, I have a link to share as well. This one is about colors on Mars in general, and everything that can go wrong:

http://www.badastronomy.com/bad/misc...rs_colors.html