Saturn | Universe Today

Carolyn Porco, the lead for Cassini's imaging team, warned on Twitter that the flyby of Saturn's moon Enceladus performed by the spacecraft on Nov. 2 wasn't really an "imaging" flyby, and that we might have to wait until the Nov. 21 flyby for really good images. But just take a look the images returned so far, with stunning looks at the jets shooting from the moon! Another image takes a close look at the surface. These are raw, unprocessed images, but what images they are! This is the second image from today's flyby returned by the spacecraft. See below for more.
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The Cassini team posted this image today, sending "bats wishes" for a happy, healthy and fun Halloween. And this give all of us here at Universe Today a chance to wish everyone a fun, safe, almost-full-Moon-lit, eat-your-favorite-treats, happy Hallow's Eve. Click the image for a larger version.

Also, as a heads up, Cassini will be flying by the moon Enceladus next week, on Nov. 2, approaching within about 100 kilometers (62 miles) of the surface. The spacecraft has gone closer during a previous flyby (25 kilometers or 15 miles), but this time it will be going deep into the heart of the plume from the geysers on the tiger-striped moon. The objective is to analyze the particles in the plume with instruments that can detect the size, mass, charge, speed and composition. This will happen at about 7:40 a.m. UTC and the spacecraft will spend only about a minute in the plume.

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Wow! This is really neat! We've long known that Saturn has aurorae, and the Cassini team recently took a series of images to see if they could catch an aurora in action near Saturn's north pole. As always, the folks at UnmannedSpaceflight.com are always on the lookout for the latest images being beamed back to Earth, and one of the UMSFer's, Astro0, saw this image series, realized what the Cassini team was trying to do, and used the images to put together this movie. You'll see Saturn's limb, moving stars, streaks that are likely cosmic ray hits, and flaring aurorae, or "curtains of light" that can sometimes rise 1,200 miles (2,000 km) above the cloud tops near Saturn's poles. Astronomers say that while aurorae on Earth shine for a few hours at most, on Saturn they can last for days. Additionally, if you were on Saturn, the aurora would look like a faint red glow. Most of the energy in Saturn's aurora is not in the form of visible light, though and instead they mostly glow in ultraviolet (UV) or infrared wavelengths. Read our previous article about the infrared aurorae at Saturn.

Thanks Astro0, (with H/T to Emily Lakdawalla)!

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The Spitzer Space Telescope has spied an enormous ring around Saturn, the largest and farthest distant band around this ringed world. Just how big is this ring? "If you had infrared eyes like Spitzer," said Anne Verbiscer, research astronomer at the University of Virginia, Charlottesville, "from Earth, it would look like one full moon on either side of Saturn." That's incredibly huge! The bulk of its material starts about six million kilometers (3.7 million miles) away from the planet and extends outward roughly another 12 million kilometers (7.4 million miles). A billion Earths could fit in the volume of space this ring occupies.

So, why hasn't this gigantic structure been detected previously?
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Two shepherding moons continue to affect Saturn's F ring in this amazing image captured by Cassini. Pandora on the outside of the ring and Prometheus on the inside, periodically create what are called "streamer-channels," seen here in the F ring. The potato-shaped Prometheus pulls a streamer of material from the ring and leaves behind a dark channel. During its 14.7-hour orbit of Saturn, Prometheus (102 kilometers, or 63 miles across) reaches the point in its elliptical path, called apoapse, where it is farthest away from Saturn and closest to the F ring, and the moon's gravity is just strong enough to draw a "streamer" of material out of the core region of the F ring.
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The Cassini team released some incredible images earlier this week of the Saturn system during equinox, and followed up with this beauty of a crescent moon Rhea beneath the rings of Saturn. NASA has also put together a multimedia presentation of recent pictures of Saturn, set to music, and it is stunning. Run, don't walk and click here to watch. (Flash required)

With these great images, it is no wonder that the leader of the Cassini imaging team, Carolyn Porco has been presented with an award for her work, the Lennart Nilsson Award for photography for capturing "worlds that are otherwise hidden from human sight." The award committee's citation reads:
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Every 14.8 Earth years, equinox occurs at Saturn. But this is the first time there has been a spacecraft in situ to watch what happens when the sun is directly overhead at the equator, illuminating the rings directly edge-on. New images compiled from the Cassini spacecraft show a rare and breathtaking display of nature: the setting of the sun on Saturn's rings. The image above — a mosaic of 75 different images — shows the beauty of this ringed world, but the most surprising revelation from these new images are that newly discovered lumps and bumps in the rings are as high as the Rocky Mountains.
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Star Trek fan? Like Cassini and Saturn? The very busy planetary scientist Carolyn Porco also has a visual graphics company, Diamond Sky Productions and they have created some new wallpapers featuring scenes from the latest Star Trek motion picture. The images are copyrighted, so we can't post them here, but no doubt you'll want to take a look at these spectacular images over at Diamond Sky's website. Enjoy!

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The Cassini spacecraft has been in orbit around Saturn since 2004 and during its mission, has watched nine different lightning storms rage on the planet. But this latest one is the longest lasting and most powerful storm yet: it has been going on since mid-January 2009 with no end in sight. It broke the storm duration record of 7.5 months set by another thunderstorm observed by Cassin between November 2007 and July 2008. Lightning discharges in Saturn's atmosphere emit very powerful radio waves which are about 10,000 times stronger than their terrestrial counterparts and the huge thunderstorms in Saturn's atmosphere have diameters of about 3,000 km.
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A new, temporary radiation belt has been detected at Saturn, located about 377,000 km from the center of the planet, near the orbit of the moon Dione. The temporary radiation belt was short-lived and formed three times in 2005. It was observed as sudden increases in the intensity of high energy charged particles in the inner part of Saturn's magnetosphere, in the vicinity of the moons Dione and Tethys, and likely was caused by a change in the intensities of cosmic rays at Saturn.
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Here's one of the first raw images of Saturn taken by the Cassini spacecraft just after equinox, on August 12, 2009. The planet sure looks naked without its rings! But not to fear, the rings are still there; we just can't see them very well — only a thin line. That's because the sun was shining directly straight-on at the rings at Saturn's equinox, and the spacecraft was in the right place, too. Equinox occurs every half-Saturn-year which is equivalent to about 15 Earth years. The illumination geometry that accompanies equinox lowers the sun's angle to the ringplane and causes out-of-plane structures and some moons to cast long shadows across the rings. The ring shadows themselves have become a rapidly narrowing band cast onto the planet. Below, see another image with the rings visible as the spacecraft changed its angle.
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Today, August 11, 2009, is Saturn's equinox. As we've been saying for a few months, the rings are going to disappear — at least from our vantage point on Earth. "Whenever equinox occurs on Saturn, sunlight will hit Saturn's thin rings, the ring plane, edge-on," said Linda Spilker, deputy project scientist for the Cassini spacecraft at Saturn. "The light reflecting off this extremely narrow band is so small that for all intents and purposes the rings simply vanish." But even from the view at Saturn, weird things are happening in the rings, and the Cassini spacecraft has a front row seat watching it all take place. Above is one of the latest raw images sent back from Cassini, taken on August 7, 2009 showing how the sunlight is hitting the edge of the rings. It is a gorgeous shot. Below, see some of the strange sights Cassini has been seeing, including a buzzsaw, a blasted ring, and tell-tale moon shadows. For more about Saturn's equinox, check out today's 365 Days of Astronomy podcast with Emily Lakdawalla of the Planetary Society and she'll tell you all about the weird and beautiful play of light and shadow going on at Saturn.
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It's more than a billion kilometers (759 million miles) away, but the more astronomers learn about Titan, the more it looks like Earth.

That's the theme of two talks happening this week at the International Astronomical Union meeting in Rio de Janeiro, Brazil. Two NASA researchers, Rosaly Lopes and Robert M. Nelson of the Jet Propulsion Laboratory in Pasadena, California, are reporting that weather and geology have very similar actions on Earth and Titan — even though Saturn's moon is, on average, 100 degrees C (212 degrees F) colder than Antarctica (and certainly much more frigid than either California or Brazil; lucky astronomers).

The researchers are also reporting a tantalizing clue in the search for life: Titan hosts chemistry much like pre-biotic conditions on Earth.

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A new estimate of Saturn's rotation rate reveals days on the gas giant are five minutes shorter than previously believed — and that Saturn's atmosphere has much in common with that of its planetary neighbor, Jupiter.

The new results appear today in the journal Nature.

(Image caption: Saturn as photographed by Cassini-Huygens. Credit: NASA)

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Cassini has imaged towering vertical structures in the planet’s otherwise flat rings that come from the gravitational effects of a small nearby moon. This is the first time these structures have been seen. They reach up over one kilometer high, and are visible now as the sun nears "high noon" directly overhead at the planet's equator, as Saturn approaches its equinox.
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