Raw Images of the Day
Since I've been gone a few days, here is a super sized "Raw Images of the Day":
- Dione and the Rings. This is great view of Dione showing the more cratered hemisphere of this particular moon.
- Trailing hemisphere of Enceladus (should show up soon)
- Herschel and the south pole of Mimas
- Crescent of Iapetus
- Clear filter view of Titan's Trailing hemisphere
- Another look at Enceladus
- Penelope crater on Tethys. Not sure why that crater is always so prominent, maybe the margins are steeper or the crater is deeper, not sure.
- Enceladus and the Rings
- Ray crater on Rhea
- Ithaca Chasma on Tethys
- More Enceladus
- Mimas with Rings
- Tethys (with Penelope crater) and Enceladus
- Cratered Mimas
- Titan with Rings
- Craters on Dione
- A better view of an Iapetus crescent
- Yet more Enceladus
- Wispy Terrain on Rhea
- Wispy Terrain on Dione
posted by Jason Perry at 10:54 AM
2 Comments:
Regarding why Penelope crater on Tethys is so prominent: it lies on a gradational light to dark boundary on Tethys. The side of Penelope lying on the darker material is brighter, the side on the brighter material is darker. (dark material is west of Penelope). So the albedo variations in Penelope are opposite to those on the backround surface, making it stand out. Topo shading adds to this effect if the crater is illuminated from the east, but if it is illuminated from the west illuminaton cancels out the albedo pattern and the crater almost disappears. These comments are based on a very detailed study of Voyager images, presented at LPSC a few years ago. When the sun is overhead on Penelope the albedo pattern makes the crater look as if it is lit by a lower sun to the east.
Thanks for the explaination. I knew about the light/dark boundary but didn't understand its relationship with Penelope. But when I need to identify a satellite, I can use Penelope as a "sign post" for Tethys (along with Odysseus and Ithaca Chasma) given its prominence in certain geometries.
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