Friday, August 15, 2014

New Cassini Images of Saturn

This morning I decided to check in with the Cassini Solstice Mission to see what new images of Saturn are available at the webpage

Seen within the vast expanse of Saturn's rings, Prometheus appears as little more than a dot. But that little moon still manages to shape the F ring, confining it to its narrow domain.

Prometheus (53 miles, or 86 kilometers across) and its fellow moon Pandora (50 miles, or 81 kilometers across) orbit beside the F ring and keep the ring from spreading outward through a process dubbed "shepherding." 

The first image above shows the geyser on one of Saturn's moons, Enceladus.  The second image is an artist's rendering showing a cross-section of the ice shell immediately beneath one of Enceladus' geyser-active fractures, illustrating the physical and thermal structure and the processes ongoing below and at the surface. Narrow cracks extend upward from the sub-surface sea all the way to the surface, through both ductile and brittle layers of the ice shell.  Liquid water under pressure fills the cracks, keeping them open even through the ductile layer and providing a conduit for vapor and sea water to reach the near-surface. Other processes, such as volatile exsolution of gases, can drive vapor and water droplets all the way to the surface, forming geysers and condensing close to the surface, depositing latent heat. This heat is observed by Cassini's long-wavelength infrared instruments as the small-scale hot spots (dozens of feet, or tens of meters, in size) surrounding each geyser. The subsurface regions immediately surrounding the cracks bearing water and vapor are expected to be warm. Regional heating from tidal flexing is also expected to be present, but is so far undetected.   The third graphic shows a 3-D model of 98 geysers whose source locations and tilts were found in a Cassini imaging survey of Enceladus' south polar terrain by the method of triangulation. While some jets are strongly tilted, it is clear the jets on average lie in four distinct "planes" that are normal to the surface at their source location.

The image above shows a colorized mosaic representing the most complete view yet of Titan's northern land of lakes and seas. Saturn's moon Titan is the only world in our solar system other than Earth that has stable liquid on its surface. The liquid in Titan's lakes and seas is mostly methane and ethane.

in the image above the Cassini spacecraft captures three magnificent sights at once: Saturn's north polar vortex and hexagon along with its expansive rings. The hexagon, which is wider than two Earths, owes its appearance to the jet stream that forms its perimeter. The jet stream forms a six-lobed, stationary wave which wraps around the north polar regions at a latitude of roughly 77 degrees North. This view looks toward the sunlit side of the rings from about 37 degrees above the ringplane. The view was obtained at a distance of approximately 1.4 million miles (2.2 million kilometers) from Saturn.

NASA/JPL-Caltech/Space Science Institute

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