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.
NGC 4522 is a spectacular spiral galaxy that is currently being stripped of its gas content. The galaxy is 60 million light-years away in the Virgo galaxy cluster. Its rapid motion within the cluster results in strong winds across the galaxy as the gas within is left behind. Scientists estimate that NGC 4522 is moving at more than 10 million kilometres per hour. (High Res)
Tourmaline is a piezoelectric material. Piezoelectrics generate a voltage when compressed along a perpendicular direction. Materials optimized for these properties are commonly used in sensors, scales, speakers, motors, and microscopes.
“There are some oddities in the perspective with which we see the world. The fact that we live at the bottom of a deep gravity well, on the surface of a gas covered planet going around a nuclear fireball 90 million miles away and think this to be normal is obviously some indication of how skewed our perspective tends to be, but we have done various things over intellectual history to slowly correct some of our misapprehensions.”
Saturn’s moon Dione, photographed by Cassini, 29 January 2011.
What’s going on with the lighting here? Dione appears to be a crescent with the light hitting only a small part of the bottom of the moon as seen from the camera, but much of the top half is also bathed in light. The streaky stars in the background suggest that these photos are each of quite long exposure, so I suspect that the very bright lower crescent is reflected sunlight, and the moderately bright upper crescent is reflected Saturnshine.