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Gorgeous Saturn

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The True Colors of Saturn and its Moons

Titan appears with Saturn behind it in this natural color view from NASA's Cassini spacecraft. NASA/JPL-Caltech/SSI.

Is there anything more lovely in the solar system than the planet Saturn? Sure, there’s Mars and the great images we’re seeing from the Curiosity rover. And, of course, Earth sports some gorgeous places. But, for sheer jaw-dropping beauty, you can’t beat a great image of Saturn and its moons. They just grab your attention.

The Cassini mission folks released a set of color “portraits” of Saturn and its largest moon Titan. They show the pair through all the seasons of Saturn’s year. And they are stunning.

A view of the night side of Titan, with sunlight scattering through the top of the atmosphere. NASA/JPL-Caltech/SSI.

A wide-angle view shows Titan passing in front of Saturn, as well as the planet’s changing colors. Upon Cassini‘s arrival at Saturn eight years ago, Saturn’s northern winter hemisphere was an azure blue.

Now that winter is encroaching on the planet’s southern hemisphere and summer on the north, the color scheme is reversing. That lovely blue is now tinting the southern atmosphere.

Saturn's rings are front and center here, obscuring part of Titan. NASA/JPL-Caltech/SSI.

The other three images depict the newly discovered south polar vortex in the atmosphere of Titan.  It’s a mass of swirling gas hovering over the pole.

Cassini‘s visible-light cameras have seen a concentration of yellowish haze in the detached haze layer at the south pole of Titan since at least March 27. Cassini‘s visual and infrared mapping spectrometer spotted the massing of clouds around the south pole as early as May 22 in infrared wavelengths. After a June 27 flyby of the moon, Cassini released a dramatic image and movie showing the vortex rotating faster than the moon’s rotation period. The four images being released today were acquired in May, June and July of 2012.

See that vortex at the south pole of Titan? It just recently formed -- and planetary scientists are studying it to understand Titan's atmospheric dynamics. NASA/JPL-Caltech/SSI.

Some of these views, such as those of the polar vortex, are only possible because Cassini’s newly inclined — or tilted — orbital path now allows more direct viewing of the polar regions of Saturn and its moons.

Over the years, Cassini has explored Enceladus and its hissing geysers, its Huygens lander probed Titan, is cameras have shown us high-resolution scans of the rings, and revealed more about the surfaces of many of Saturn’s moons.  This system continues to surprise us with each new set of images and data that Cassini sends back.

I don’t know about you, but when it comes to return on investment, I’d have to say that we’re totally getting our money’s worth out of the Cassini mission. I suspect (but I haven’t calculated it directly) that this mission has probably cost the average taxpayer a few pennies.  And, for that, we’re getting some fantastic looks at the outer solar system.

cassini mission, saturn

Titanic Ocean?

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Could Well Be!

This artist's concept shows a possible scenario for the internal structure of Titan, as suggested by data from NASA's Cassini spacecraft. Scientists have been trying to determine what is under Titan's organic-rich atmosphere and icy crust. Image credit: A. Tavani

The more we explore the outer solar system with probes like the Cassini spacecraft, the cooler things we discover. This week planetary scientists working with data from that spacecraft announced that there’s a good chance Saturn’s moon Titan has a layer of liquid water hidden beneath that desolate icy surface.

The discovery came from the study of tides on Titan.  This moon is squeezed and stretched as it orbits Saturn, and that is bound to cause some heating in the core.  It’s also a shape-changing process.

The scientists figured out that Titan is not a big rocky ball that would show a slight bulge on its surface as Saturn’s strong gravitational pull tugged on it.  The way they did this is quite ingenious.  They looked at Titan during its 16-day orbit of Saturn.  As it whirls around the huge planet, Titan’s shape changes and scientists could chart those changes.  Titan is not a perfectly round sphere. Instead, it’s slightly elongated like a football. As it orbits Saturn, its  long axis grows when it’s closer to Saturn. Eight days later, when Titan is farther from Saturn, it’s much less elongated and more nearly round. Cassini measured the gravitational effect of that squeeze and pull.  These measurements and the assessment of Saturn’s gravitational pull on Titan provide the best data yet of  Titan’s internal structure and what they show is that for the shape to change as much as it does, Titan likely has a an ocean layer.  It’s not necessarily a huge or deep one, but the fact that it’s there at all is one more step in learning more about Titan’s structure.

Now, I read a few stories here and there about how this supposed ocean is darn near proof that life could exist on Titan.

Not so fast.  The presence of a subsurface layer of liquid water at Titan is not necessarily an indicator for life. There are still a lot of studies to be done before scientists understand what Titan looks like in its interior, and whether or not the conditions are right for life to exist in that ocean, or perhaps at a rock-water interface deep inside.

The implications of an ocean in Titan is an exciting finding, no matter what else is discovered there. This mysterious, cloudy world is slowly yielding up its secrets, and in the process, is opening our minds about what other surprises we’re going to find in, on, or near the worlds of the outer solar system.