Happy Holidays from Cassini!

Cassini couldn’t make it to the mall this year to do any Christmas shopping but that’s ok: we’re all getting something even better in our stockings than anything store-bought! To celebrate the holiday season the Cassini team has shared some truly incredible images of Saturn and some of its many moons for the world to “ooh” and “ahh” over. So stoke the fire, pour yourself a glass of egg nog, sit back and marvel at some sights from a wintry wonderland 900 million miles away…

Thanks, Cassini… these are just what I’ve always wanted! (How’d you know?)

Saturn’s southern hemisphere is growing more and more blue as winter approaches there — a coloration similar to what was once seen in the north when Cassini first arrived in 2004:

Saturn's southern hemisphere images from a million miles away (Credit: NASA/JPL-Caltech/Space Science Institute)
Saturn’s southern hemisphere images from a million miles away (Credit: NASA/JPL-Caltech/Space Science Institute)

(The small dark spot near the center right of the image above is the shadow of the shepherd moon Prometheus.)

Titan and Rhea, Saturn’s two largest moons, pose for Cassini:

Rhea (front) and Titan, images by Cassini in June 2011 (Credit: NASA/JPL-Caltech/Space Science Institute)
Rhea (front) and Titan, images by Cassini in June 2011 (Credit: NASA/JPL-Caltech/Space Science Institute)

The two moons may look like they’re almost touching but in reality they were nearly half a million miles apart!

Titan’s northern “land of lakes” is visible in this image, captured by Cassini with a special spectral filter able to pierce through the moon’s thick haze:

Titan images by Cassini on Oct. 7, 2013 (Credit: NASA/JPL-Caltech/Space Science Institute)
Titan images by Cassini on Oct. 7, 2013 (Credit: NASA/JPL-Caltech/Space Science Institute)

Read more: Titan’s North Pole is Loaded with Lakes

The frozen, snowball-like surface of the 313-mile-wide moon Enceladus:

Enceladus: a "snowball in space" (Credit: NASA/JPL-Caltech/Space Science Institute)
Enceladus: a highly-reflective and icy “snowball in space” (Credit: NASA/JPL-Caltech/Space Science Institute)

(Even though Enceladus is most famous for its icy geysers, first observed by Cassini in 2005, in these images they are not visible due to the lighting situations.)

Seen in a different illumination angle and in filters sensitive to UV, visible, and infrared light the many fractures and folds of Enceladus’ frozen surface become apparent:

View of the trailing face of Enceladus (Credit: NASA/JPL-Caltech/Space Science Institute)
View of the trailing face of Enceladus (Credit: NASA/JPL-Caltech/Space Science Institute)

Because of Cassini’s long-duration, multi-season stay in orbit around Saturn, researchers have been able to learn more about the ringed planet and its fascinating family of moons than ever before possible. Cassini is now going into its tenth year at Saturn and with much more research planned, we can only imagine what discoveries (and images!) are yet to come in the new year(s) ahead.

“Until Cassini arrived at Saturn, we didn’t know about the hydrocarbon lakes of Titan, the active drama of Enceladus’ jets, and the intricate patterns at Saturn’s poles,” said Linda Spilker, the Cassini project scientist at NASA’s Jet Propulsion Laboratory. “Spectacular images like these highlight that Cassini has given us the gift of knowledge, which we have been so excited to share with everyone.”

Read more about the images above and see even more on the CICLOPS  Imaging Team website, and see the NASA press release here.

Thanks to Carolyn Porco, Cassini Imaging Team Leader, for the heads-up on these gifs — er, gifts!

Saturn’s Mysterious Hexagon Behaves Like Earth’s Ozone Hole

A raging hurricane is creating a “suck zone” at Saturn’s north pole. The handy Cassini spacecraft recently captured a bunch of images of the six-sided jet stream surrounding the storm, which mission managers then put together into an awesome animation showing the wind currents shifting. (You can see the animation below the jump.)

The feature is pretty in a picture, but NASA has a special interest because there is nothing else like this anywhere in our solar system, the agency stated. The immense storm stretches 20,000 miles (30,000 kilometers) across with winds whipping in its jet stream at 200 miles per hour (322 kilometers per hour). And despite all the turbulence, the storm is staying put at the north pole for reasons scientists are still trying to understand.

“The hexagon is just a current of air, and weather features out there that share similarities to this are notoriously turbulent and unstable,” said Andrew Ingersoll, a Cassini imaging team member at the California Institute of Technology in Pasadena. “A hurricane on Earth typically lasts a week, but this has been here for decades — and who knows — maybe centuries.”

An animation of Cassini Saturn images showing a hexagonal jet stream surrounding a storm at the north pole. Credit: NASA/JPL-Caltech/SSI/Hampton University
An animation of Cassini Saturn images showing a hexagonal jet stream surrounding a storm at the north pole. Credit: NASA/JPL-Caltech/SSI/Hampton University

Cassini has been orbiting Saturn since 2004, but it’s only since last year that it’s been able to peer at the hexagon with much success. That’s because the angle of the sun is finally favorable to peer at the storm. This has allowed scientists, for example, to look at the types of particles inside. They discovered that the jet stream is a sort of barrier around the storm, delineating a location with a lot of small haze particles and few large haze particles. (It’s the opposite outside of the jet stream). Scientists said it looks like the Antarctic ozone hole on Earth.

“The Antarctic ozone hole forms within a region enclosed by a jet stream with similarities to the hexagon,” NASA stated.

“Wintertime conditions enable ozone-destroying chemical processes to occur, and the jet stream prevents a resupply of ozone from the outside. At Saturn, large aerosols cannot cross into the hexagonal jet stream from outside, and large aerosol particles are created when sunlight shines on the atmosphere. Only recently, with the start of Saturn’s northern spring in August 2009, did sunlight begin bathing the planet’s northern hemisphere.”

Should Cassini have enough funding to function for a few more years, scientists are eager to watch as Saturn gets to its summer solstice in 2017 and the lighting gets even better around the north pole.

NASA also held an interesting Google+ Hangout yesterday (Nov. 4) about Saturn and the Cassini mission that featured Carolyn Porco, director of the Cassini Imaging Team and the Cassini Imaging Central Laboratory for Operations (CICLOPS). The whole video below is worth a watch, but here’s a little tidbit to let you know some of what was talked about:

“If you took all the mass of Saturn’s rings and recomposed it into a moon, it would be no bigger than Enceladus, so it’s a big spectacle coming from little mass,” Porco said. “The main rings are very thin, only about 30 feet [9 meters] thick, no bigger than about 2 stories in a modern day building. Despite the fact they are about 280,000 km [174,000 miles] across.”

A New Look at Saturn’s Northern Hexagon

Freshly delivered from Cassini’s wide-angle camera, this raw image gives us another look at Saturn’s north pole and the curious hexagon-shaped jet stream that encircles it, as well as the spiraling vortex of clouds at its center.

Back in November we got our first good look at Saturn’s north pole in years, now that Cassini’s orbit is once again taking it high over the ringplane. With spring progressing on Saturn’s northern hemisphere the upper latitudes are getting more and more sunlight — which stirs up storm activity in its atmosphere.

The bright tops of upper-level storm clouds speckle Saturn’s skies, and a large circular cyclone can be seen near the north pole, within the darker region contained by the hexagonal jet stream. This could be a long-lived storm, as it also seems to be in the images captured on November 27.

About 25,000 km (15,500 miles) across, Saturn’s hexagon is wide enough to fit nearly four Earths inside!

The Saturn hexagon as seen by Voyager 1 in 1980 (NASA)
The Saturn hexagon as seen by Voyager 1 in 1980 (NASA)

The hexagon was originally discovered in images taken by the Voyager spacecraft in the early 1980s. It encircles Saturn at about 77 degrees north latitude and is estimated to whip around the planet at speeds of 354 km/h (220 mph.)

Watch a video of the hexagon in motion here.

The rings can be seen in the background fading into the shadow cast by the planet itself. A slight bit of ringshine brightens Saturn’s nighttime limb.

Cassini was approximately 579,653 kilometers (360,180 miles) from Saturn when the raw image above (W00079643) was taken.

Image credit: NASA/JPL/Space Science Institute

 

Saturn’s Strange Hexagon – In Living Color!

Color-composite Cassini image of Saturn’s northern hexagon (NASA/JPL/SSI/Jason Major)

Cassini sure has been busy these past few days! After returning some mind-blowing images of the swirling 3,000-km-wide cyclone over Saturn’s north pole the spacecraft pulled back to give a wider view of the ringed giant’s upper latitudes, revealing one of its most curious features: the northern hexagon.

The image above is a color-composite made from raw images acquired by Cassini on November 28 from a distance of 379,268 miles (610,373 kilometers) away. Because the color channels were of a much lower resolution than the clear-filter monochrome image, the color is approximate in relation to individual atmospheric details. Still, it gives an idea of the incredible variation in hues around Saturn’s northern hemisphere as well as clearly showing the uncannily geometric structure of the hexagon.

(Can I get another “WOW”?)

Made of a band of upper-atmospheric winds, for some reason at this latitude the stream forms a six-sided hexagonal shape. The entire structure is about 25,000 km across — large enough for four Earths to fit inside! The polar cyclone can be seen at the very center.

First seen by Voyagers 1 and 2 over 30 years ago the hexagon appears to be fixed with Saturn’s rotation rate, which is a remarkably speedy 0.44 Earth-days (about 10.5 hours.)

“This is a very strange feature, lying in a precise geometric fashion with six nearly equally straight sides,” said atmospheric expert and  Cassini team member Kevin Baines back in 2007. “We’ve never seen anything like this on any other planet. Indeed, Saturn’s thick atmosphere where circularly-shaped waves and convective cells dominate is perhaps the last place you’d expect to see such a six-sided geometric figure, yet there it is.”

As scientists puzzled over the mechanisms behind the geometric feature, they came to the conclusion that not only is it a very natural occurrence, it’s also something that is not uncommon in fluid dynamics… apparently its sides are bound by the eddying storms. (Read more in this article by Nicole Gugliucci.)

Here are some more raw images from Cassini’s Nov. 28 pass:

Amazing! Here we are well over 8 years after arriving at Saturn and Cassini is still astounding us almost daily with views of the ringed world. (I knew it was my favorite planet for a reason!)

As always, stay tuned to Universe Today for more!

Image credits: NASA/JPL/Space Science Institute. Color-composite by Jason Major.

 

Incredible Raw Image of Saturn’s Swirling North Pole

Ok, are you ready for this?

I know… WOW.

This swirling maelstrom of clouds is what was seen over Saturn’s north pole earlier today, November 27, by NASA’s Cassini spacecraft. This is a raw image, acquired in polarized light, from a distance of 238,045 miles (383,097 kilometers)… all I did was remove some of the hot pixels that are commonly found on Cassini images taken with longer exposures.

Again… WOW.

My attempt at a color composite can be seen below, plus another treat:

It’s rough, and a little muddy because the clouds were moving between image channels (not to mention the blue channel image was rather underexposed) but here’s a color-composite of the same feature, made from images taken from a slightly different perspective:

Color composite of Saturn’s north polar vortex

Pretty darn cool… Cassini does it yet again!

The images above show an approximately 3,000-4,000-km-wide cyclone above Saturn’s north pole. Saturn is also known to have a long-lived hexagonal jet stream feature around its north pole as well, but that is not shown in those images as it runs along a lower latitude. Instead, you can see that HERE:

Saturn’s northern hexagon

Captured with a wider angle, in this image the hexagon structure can be made out as well as the cyclone, which sits at the center just over the pole. Saturn’s hexagon is about 25,000 km (15,500 miles) in diameter… large enough to fit almost four Earths inside. This image was also acquired today.

An RGB composite of this feature is below:

Saturn’s northern hexagon – color composite

It’s been a few years since we’ve gotten such a good look at Saturn’s north pole… thanks to Cassini’s new orbital trajectory, which is taking it high above the ring plane and poles of Saturn, we now have the opportunity to view the gas giant’s dynamic upper latitudes again. I’m sure this is just a taste of what’s to come!

(Image credit: NASA/JPL/Space Science Institute. Color composites by Jason Major)