A collection of planetary nebulae; clouds of ionized gas that form as red giant stars die and cast off their outer layers. This process enriches interstellar space with heavy elements that go on to form new stars and planets.
What’s that behind Titan? It’s another of Saturn’s moons: Tethys. The robotic Cassini spacecraft orbiting Saturn captured the heavily cratered Tethys slipping behind Saturn’s atmosphere-shrouded Titan. The largest crater on Tethys, Odysseus, is easily visible on the distant moon. Titan shows not only its thick and opaque orange lower atmosphere, but also an unusual upper layer of blue-tinted haze. Tethys, at about 2 million kilometers distant, was twice as far from Cassini as was Titan when the above image was taken. In 2004, Cassini released the Hyugens probe which landed on Titan and provided humanity’s firstviews of the surface of the Solar System’s only known lake-bearing moon.
In 2009, amateur image processor (and philosophy professor) Ted Stryk discovered something no one had recognized before — images that show the shadow of Despina in transit across Neptune’s blue cloud tops. His composite view of Despina and its shadow is composed of four archival frames taken on 24 August 1989, separated by nine minutes. Despina itself has been artificially brightened to make it easier to see.
River Deltas around the world, imaged with the ASAR radar instrument on ESA’s Envisat spacecraft. Colors in these images are generated from the differences in surface texture between flybys of each location.