domingo, 2 de octubre de 2011
The Massive Vertical Structures Towering Above Saturn's Rings
This one is a 10 on the Galaxy wow meter: In images made possible only as Saturn nears equinox, NASA's Cassini spacecraft has uncovered for the first time towering vertical structures in the planet's otherwise flat rings that are attributable to the gravitational effects of a small nearby moon.
The search for material extending well above and below Saturn's ring plane has been a major goal of the imaging team during Cassini's "Equinox Mission," the two-year period when the sun is seen directly overhead at noon at the planet's equator. This novel illumination geometry, which occurs every half-Saturn-year, or about 15 Earth years, lowers the sun's angle to the ring plane and causes out-of-plane structures to cast long shadows across the rings' broad expanse, making them easy to detect.
Cassini's cameras spotted not only the predictable shadows of some of Saturn's moons, but also the shadows of newly revealed vertical structures in the rings themselves. And these observations have lent dramatic support to the analysis that demonstrates how small moons in very narrow gaps can have considerable and complex effects on the edges of their gaps, and that such moons can be smaller than previously believed.
Images showing the shadows cast by the vertical waves on the edges of the Keeler gap
Source: The Daily Galaxy - NASA/Cassini