Cassini – Christian Ready

16 October, 201316 October, 2013

An Overhead View of Saturn

On October 10, 2013, the Cassini spacecraft took an image of Saturn that is unlike anything we’ve ever seen from Earth:

It’s unlike any view of Saturn we’ve ever seen from Earth because it’s a view we can never see from Earth! Cassini captured Saturn and it’s rings from high above the planet’s northern hemisphere on October 10, 2013. The image shown here is actually a composite of several mosaic images of Saturn and its rings taken in red, green, and blue filters.

And what an image it is! In a rare glimpse we see Saturn as its own planet, detached from its rings. Of course, we already knew that about Saturn, but seeing it this way seems to add a whole new…well…perspective.

The image reveals some striking features of the planet. At the north pole is a 1,250 mile-(2,000 kilometers) wide vortex with wind speeds up to 330 mph (150 meters per second). There’s no land mass on Saturn to break this storm and it’s likely that it’s been there since long before Cassini ever arrived, and will probably remain there for centuries to come.

The storm sits at the center of a complex region known as the hexagon, shown in light blue in this image. Each side of the hexagon is over 8,600 miles (13,800 km) in length – more than the diameter of Earth itself! For some reason though, there is no similar hexagon in Saturn’s southern hemisphere.

Looking at the rest of the image, the first thing that jumped out at me was that you could still clearly see the night side of the planet. That’s because Saturn is being illuminated by the rest of the ring system itself!

Had they been able to, I’m sure NASA would have processed the images and shared it with the public in a press release. But due to the government shutdown, no image was produced. Fortunately, the raw data is public and Gordan Ugarkovic at UnmannedSpaceFlight.com created this spectacular image on his own initiative.

On a personal note, I’m extremely grateful for this image because it was taken on October 10, my birthday. So thank you Cassini, and thank you Gordan for an amazing birthday present! 🙂

27 July, 2013

Waltz Around Saturn

It’s hard to believe that the Cassini spacecraft has been in orbit around Saturn for nearly a decade now, returning one amazing image of the ringed world and its moons after another. The images are nothing short of breathtaking, but often only become so after some careful work has been done by humans here on earth to remove artifacts, add colors, and general image processing that must be done to make sense of astronomical data.

But there’s a kind of gritty beauty in the raw, unprocessed images as well, so when filmmaker Fabio Di Donato synced them to Shostakovich – Jazz Suite No.2: VI. Waltz 2, the result is a thing of beauty:

Around Saturn from fabio di donato on Vimeo.

I’ve been watching this video over and over again for the last several days and every time I do, I see something new in it. The intricate patterns of the ring system, it’s outer F-ring being deformed by Prometheus, Mimas floating by, the spongy texture of Hyperion, and the eye of Iapetus give the feel that the moons of the Saturn system are all in a kind of cosmic dance.

And what a beautiful dance it is! The whole thing looks like something directed by Stanley Kubrick and David Lynch using a silent film-era movie camera.

The whole video is a joy to watch, and a beautiful portrait of exotic, alien worlds right here in our cosmic front yard.

24 December, 2012

In Saturn’s shadow, part deux

The Cassini mission to Saturn has given us one astonishing view of the ringed planet and its moons after another since 2004, but this is one for the books:

saturn_rear — Saturn’s night side, as seen by Cassini on Oct. 17, 2012 at a distance of approximately 500,000 miles (800,000 kilometers) from Saturn. Get the full-resolution image here! Image credit: NASA/JPL-Caltech/Space Science Institute

Is that amazing or what? And you really have to get the full-resolution, 6672×3104-pixel image to really grok the awesomeness. This image was created on October 17, 2012 by the Cassini spacecraft while Saturn was backlit by the Sun. In other words, this is Saturn’s night side. The image was taken when Cassini was looking “up” towards Saturn’s equator from an orbital latitude of about 19 degrees. The result is a stunning image of the planet’s silhouette, surrounded by the backlit rings.

There is a lot going on here and Phil Plait has a great breakdown of all of the features of the image, so I’ll refer you there. But I should like to point out that the green glow is light reflected by the rings onto Saturn’s cloud tops. In other words, forget moonlight, this is ringlight!

Another feature that is really cool is the diffuse band of light toward the bottom of the image. This is the outermost E-ring, which is the least dense and most diffuse of the rings. This ring comes courtesy of Saturn’s moon Enceladus, which spews geysers of water vapor and ice as it orbits Saturn.

Enceladus in Saturn’s E-ring. Enceladus appears as the dark spot in the middle of the flare at center. Image credit: NASA/JPL/Space Science InstituteNASA/JPL/Space Science Institute

It’s worth mentioning that these colors aren’t real, but are a combination of infrared, red and violet spectral filters. When combined, Saturn takes on a serene, eerie hue that reveals subtle details in its atmosphere that you simply cannot get any other way.

Since the only way to obtain an image like this is when the Cassini spacecraft is directly behind Saturn, such images are very rare. The last time this sort of image was taken was back in 2006. During that encounter, images were taken using filters to create a natural-color view of the backlit planet:

In Saturn’s Shadow – the Pale Blue Dot. Image credit: NASA/JPL/Space Science Institute

And if you haven’t, you must click that image for the full view. If you look carefully, you’ll see a pale blue dot in that image on the left side just inside G-ring. That’s Earth. That’s home. That’s us.

And we made this.

10 October, 20129 October, 2012

Saturn, down under

It’s hard to believe that the Cassini mission to Saturn has been in operation for over a decade now. So much has been learned about Saturn, its rings, and its moons, but nothing of course compares to the steady stream of jaw-dropping images like this:

Saturn, 01 October 2012 — Saturn, seen from its southern hemisphere by the Cassini spacecraft on 1 October 2012. Image Credit: NASA/JPL/Space Science Institute

As winter starts to set in in Saturn’s southern hemisphere, the planet’s northern hemisphere and rings are tilted toward the Sun, casting an array of shadows into the cloud tops of the southern hemisphere. So this image is looking “up” towards the southern hemisphere of Saturn, when Cassini was about 1,427,863 miles (2,297,923 kilometers) away.

That’s close enough to make out a range of features. The most striking feature is the thick black shadow cast by Saturn’s innermost ring, followed by a series of thinner shadows cast by outer rings. In fact, the shadows themselves create a kind of “negative” of the rings themselves, the rings are black and the main gap between the rings – the Cassini division – shows up as white!

Now, I love full-color images of Saturn as much as the next person. But there’s something about the raw, unprocessed black-and-white images of Saturn that are just incredible. In fact, this image was made with Cassini’s “clear” filters, which is as close to a truly raw, unfiltered image of Saturn you can get. In fact, you should really check out the full-resolution version which shows off the details in all of its awesome raw-iness.

This image also illustrates how fundamentally different it would be to live on the surface of a planet like Saturn (ignoring for the moment that Saturn doesn’t have a solid surface to live upon). Seasons would be very different at different latitudes within the hemispheres. Some regions would still see the sun during the daytime, while others would be in permanent shadow for several months. Imagine looking up at the sky to see the rings backlit by the sun every day!

To really get your mind going, imagine what would be like to live on a moon where the Sun is blocked by the rings, then unblocked, then blocked again by the rings, then unblocked, then blocked again by Saturn itself, etc. That would be an absolutely crazy diurnal cycle!