Celestia Forums

Hi:

I ran across Cassini's latest image of Titan and its two layered atmosphere. The media claims it is a true color image, showing the atmosphere to be a deep purplish tint. Here is the latest Cassini image that I have discovered:



As you can see, the atmosphere is whitish purple near the surface, fading into deep purple then black as you ascend, then picking up a pale tint in the 2nd layer.

When I loaded Celestia's latest default image of Titan, the atmosphere is orange/beige. Here is a screenshot:



Not much like the Cassini view.

I have adjusted the atmosphere settings to more closely match Cassini. Here is the Celestia result:



I tried to create a two layered atmosphere by leaving the lower layer of the ssc file black, but it did not show well. It anyone knows how, that would be great.

Anyway, I think the match is not bad.

If you agree, here is the ssc code to make the change in the solarsys.ssc entry for Titan:

Atmosphere {
Height 450
Lower [ 0.5 0.5 0.6 ]
Upper [ 0.17 0.05 0.4 ]
Sky [ 1.0 0.91 1.0]
CloudHeight 10
CloudSpeed 10
CloudMap "titan-clouds.*"
}


Regards,

Frank

I think that it is strange how Titan's upper atmosphere would be purple, What makes this even weirder is that it brightens up higher in the atmosphere.

I think that Celestia's original Titan atmosphere makes the famous moon look like an artist's impression I've seen of the severe epistellar planet Tau Bootes b.

Michael Kilderry

fsgregs wrote:Hi:

I ran across Cassini's latest image of Titan and its two layered atmosphere. The media claims it is a true color image, showing the atmosphere to be a deep purplish tint. Here is the latest Cassini image that I have discovered:



...
Regards,

Frank

Frank,

it is always worthwhile to read the caption of such images first. I quote some relevant part for you:

Cassini-Huygens/NASA wrote:The image was taken using a spectral filter sensitive to wavelengths of ultraviolet light centered at 338 nanometers. The image has been falsely colored: The globe of Titan retains the pale orange hue our eyes usually see, and both the main atmospheric haze and the thin detached layer have been brightened and given a purple color to enhance their visibility.

Against my personal preferences, we so far seem to have agreed that we restrict the features to be displayed in Celestia to the visual wavelength band!

In absence of any credible /true color/ information about the lower part of Titan's atmosphere, I had chosen in the default Titan package for Celestia 1.3.2 a similar orange/beige color as on the cloud texture .

Bye Fridger

Fridger:

I obtained the image from a news article that omitted the original caption. I thought the article said it was a true color image. I humbly stand corrected.

Thanks. Somehow, I knew when I was making the correction that I might have missed something and would probably be hearing from you.

Frank

fsgregs wrote:Fridger:

I obtained the image from a news article that omitted the original caption. I thought the article said it was a true color image. I humbly stand corrected.

Thanks. Somehow, I knew when I was making the correction that I might have missed something and would probably be hearing from you.

Frank

Frank,

I figured something like this had happened. But let me emphasize again, that I would be more than happy to have Celestia entering a multi-spectral band display phase in the future. Also for me it was very tempting to display the UV aspects of Titan's atmosphere as an option!

Bye Fridger