Astronomie - Im Focus von Cassini: Saturn-Monde Titan, Rhea und Mimas


Titan, Rhea and Mimas. (NASA/JPL-Caltech/Space Science Institute)
In a new image released by NASA, the Cassini orbiter captures three of Saturn's moons as crescents. It's a rare glimpse of what treats the night sky might offer if we had more than one moon.The photo,s taken March 25, also shows how different the three moons are.
Mimas, which is just 246 miles across, is mostly made of ice and has a rough, cratered surface, making its crescent appear notched. You won't see its most famous characteristic in the above photo -- its biggest crater makes it resemble the Death Star, a space station from the "Star Wars" films.
Rhea is a more substantial 949 miles across, but also has cratered ice roughing it up.Titan, which is Saturn's largest moon at about 3,200 miles across, looks fuzzy because of its dense atmosphere, which is scattering the light. Titan is the only moon known to have such a substantial atmosphere, and it's also thought to have lakes and flowing water. The dense atmosphere creates a thick yellowish haze that we're not used to seeing around a moon, so it doesn't have the sharp crescent you might expect. But because of that light refraction, the crescent -- though hazy -- wraps a little farther around the moon than it would otherwise, making for a dramatic swoop in the sky.
Quelle: The Washington Post