Feb 11, 2014: Saturn's Colorful Aurora - While the curtain-like auroras we see at Earth are green at the bottom and red at the top, NASA's Cassini spacecraft has shown us similar curtain-like auroras at Saturn that are red at the bottom and purple at the top to the human eye. (Press release can be found here.)
July 12, 2012
One of the main contributing factors to the enormous success we have enjoyed in Cassini's exploration of Saturn is the capability to view the planet and the bodies around it from a variety of directions. Setting the spacecraft high into orbit above Saturn's equator provides us direct views of the equatorial and middle latitudes on the planet and its moons, while guiding it to high inclination above the equator plane affords the opportunity to view the polar regions of these bodies and be treated to vertigo-inducing shots of the planet's glorious rings.
After a residence time of almost 2.5 years in near-continuous equatorial orbits, Cassini recently took off on a steeply inclined orbital excursion that will send it above and below the rings, over and over again, for the next three years. And already, startling results are in hand from our first months on this new trajectory.
As a dramatic opening, our first views of Saturn's rings in about two years brought new insights concerning the orbits of the famed "propeller" features ... small, longitudinally limited, orbiting gaps in the rings that are cleared out by bodies smaller than known moons but larger than typical ring particles. First sighted a few years ago in our images, their reappearance in approximately the position we predicted indicates that we understand their behavior well enough to find them years later, but not well enough to get it exactly right. Our best guess is that the orbits of these tiny gap-forming moons are being altered by interactions with the particles in Saturn's ring ... interactions we are keen to understand as they may hold a key to the behavior of newly formed planets growing out of disks of matter in orbit around other stars in our galaxy and beyond.
Next up was the marvelous reveal of a swirling, whirling vortex forming high in the atmosphere overlying the south pole of Titan, Saturn's largest moon, as the moon's southern hemisphere slowly becomes engulfed in the darkness of deep autumn. We've long known that the winter hemisphere of Titan can exhibit a polar 'hood' of haze made of condensing organic compounds. We suspect that this maelstrom, clearly forming now over the south pole and spinningmore than forty times faster than the moon's solid body, may be a harbinger of what will ultimately become a south polar hood as autumn there turns to winter. Of course, only time will tell.
In the meantime, note the motions and beautifully detailed cloud patterns -- very likely the result of open-cell convection -- already visible in this fascinating phenomenon that we on Cassini have been fortunate to capture, for the first time, in the process of being born.
There will be more to come in this most amazing of journeys we have undertaken around Saturn. Stay with us, my friends, and be as we have been ... transformed.
Carolyn Porco Cassini Imaging Team Leader Director, CICLOPS Boulder, CO