Celestia Forums

While browsing the latest batch of raw images from Cassini, I found some shots of Saturn's icy satellites. finally with enough detail to be interesting.

Rhea:
http://saturn1.jpl.nasa.gov/multimedia/ ... 006616.jpg
http://saturn1.jpl.nasa.gov/multimedia/ ... 006676.jpg
Some experimentation in Celestia seems to show that these are heretofore unseen areas of Rhea.

Tethys:
http://saturn1.jpl.nasa.gov/multimedia/ ... 006677.jpg

Dione:
http://saturn1.jpl.nasa.gov/multimedia/ ... 006615.jpg
Notice how brightly the night side of Dione is illuminated by 'Saturn-shine' (which given Saturn's size and higher overall reflectivity, is a much more significant source of illumination than Earthshine.)

Mimas:
http://saturn1.jpl.nasa.gov/multimedia/ ... 006614.jpg
Not a great image at all, but . . . Can anyone tell what's going on here? Some sort of shadow from Saturn or its rings perhaps?

Iapetus:
http://saturn1.jpl.nasa.gov/multimedia/ ... 006667.jpg
Not much detail visible here; however, the contrast between the dark and light regions is striking.

--Chris

chris wrote:Mimas:
http://saturn1.jpl.nasa.gov/multimedia/ ... 006614.jpg
Not a great image at all, but . . . Can anyone tell what's going on here? Some sort of shadow from Saturn or its rings perhaps?

Saturnlight? At this season the Saturnlight terminator and the sunlight terminator are going to be inclined by around 27 degrees relative to each other - so if Saturn is illuminating Mimas on its nightside, this might make sense (although the angle between the illuminated sectors does seem visually too large).

Grant

granthutchison wrote:

chris wrote:Mimas:
http://saturn1.jpl.nasa.gov/multimedia/ ... 006614.jpg
Not a great image at all, but . . . Can anyone tell what's going on here? Some sort of shadow from Saturn or its rings perhaps?

Saturnlight? At this season the Saturnlight terminator and the sunlight terminator are going to be inclined by around 27 degrees relative to each other - so if Saturn is illuminating Mimas on its nightside, this might make sense (although the angle between the illuminated sectors does seem visually too large).

That must be it . . . Saturnlight is a much more significant contribution to total illumination of Mimas than Earthlight is for the Moon, and the overexposure of the image makes it even more dramatic.

--Chris

So how soon will Celestia support illumination from an extended secondary light source?

It can be simulated turning the light level to medium maybe...