• Who knew a monstrous Saturnian hurricane could look so lovely?

    NASA / JPL-Caltech / SSI

    The spinning vortex of Saturn's north polar storm resembles a deep red rose in this false-color image from NASA's Cassini spacecraft. Measurements have sized the eye at a staggering 1,250 miles (2,000 kilometers) across with cloud speeds as fast as 330 miles per hour (150 meters per second). This image was taken from a distance of 261,000 miles (419,000 kilometers) on Nov. 27, 2012, with filters sensitive to near-infrared light.

    By Alan Boyle, Science Editor, NBC News


    The eye of a super-hurricane at Saturn's north pole looks like a peaceful red rose in a fresh bouquet of pictures from NASA's Cassini orbiter. But don't be fooled: That rosy appearance is merely due to the false colors ascribed to infrared wavelengths.

    This storm's eye measures 1,250 miles (2,000 kilometers) in diameter, about 20 times wider than the average hurricane's eye on Earth. The outer clouds at the hurricane's edge are traveling at 330 mph (530 kilometers per hour), which would be off the scale on our planet. The vortex whirls inside Saturn's mysterious hexagonal cloud pattern, and it's not going anywhere.

    "We did a double take when we saw this vortex, because it looks so much like a hurricane on Earth," Caltech's Andrew Ingersoll, a member of the Cassini imaging team, said in a NASA news release on Monday. "But there it is at Saturn, on a much larger scale, and it is somehow getting by on the small amounts of water vapor in Saturn's hydrogen atmosphere."

    On Earth, hurricanes are fed by warm ocean water. But there are no oceans on Saturn — so what source drives this super-hurricane? Cassini's scientists want to find out, and whatever they find might add to our understanding of storm dynamics on Earth as well.

    The Cassini team suspects that this storm has been active for years, but Cassini has only recently been able to watch it in visible light. When the bus-sized spacecraft arrived in 2004 to begin its $3.5 billion mission to study Saturn and its moons, the north pole was shrouded in winter darkness. Now spring is coming to the north, and Cassini has shifted to an orbit that makes it easier to see the increasingly sunlit storm.

    In an email, Cassini imaging team leader Carolyn Porco of the Colorado-based Space Science Institute said the hexagon-ringed vortex is "one of the most gorgeous sights we have been privileged to see at Saturn." But such sights won't last forever: Cassini's extended mission to Saturn is due to end in 2017 with a controlled plunge into Saturn's clouds.

    To keep up with the mission in its final years, check in on NASA's Cassini website as well as the online home of the Cassini imaging team, and follow @CassiniSaturn on Twitter.  

    NASA / JPL-Caltech / SSI

    A false-color image from Cassini highlights the storms at Saturn's north pole. The angry eye of a hurricane-like storm appears dark red, while the fast-moving hexagonal jet stream framing it is a yellowish green. Low-lying clouds circling inside the hexagonal feature appear in a muted orange color. A second, smaller vortex pops out in teal at the lower right of the image. The rings of Saturn appear in vivid blue at the top right. The colors are coded to show different near-infrared wavelengths, which are associated with different altitudes.

    Andy Ingersoll, a member of the Cassini orbiter's imaging team, narrates a NASA video about a hurricane-like storm seen at Saturn's north pole.

    Slideshow: Best of Cassini

    The Cassini spacecraft is sending back unprecedented imagery of Saturn, its rings and its moons. Click "Launch" to see some of the greatest hits from the Cassini mission.

    Launch slideshow

    Update for 8:25 p.m. ET April 30: NBC Nightly News anchor Brian Williams found these pictures as awe-inspiring as I did. Here's the video clip:

    The spacecraft Cassini has provided close-up views of a large hurricane at Saturn's north pole that's estimated to be about 1250 miles wide. NBC's Brian Williams reports.

    More beauties from Saturn:

    Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. To keep up NBCNews.com's stories about science and space, sign up for the Tech & Science newsletter, delivered to your email in-box every weekday. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

    Slideshow: Month in Space: April 2013

    Chris Hadfield / Canadian Space Agency

    Feast your eyes on an alligator-like mountain range and other curiosities seen from outer space in April 2013.

    Launch slideshow

  • NASA craft snaps last close-up photos of icy Saturn moon

    NASA/JPL/Space Science Institute

    This raw image of Saturn's icy moon Rhea was taken on March 10, 2013 by NASA's Cassini spacecraft. The camera was pointing toward Rhea at approximately 174,181 miles away.

    By Mike Wall, SPACE.com

    NASA's Cassini spacecraft has snapped its last up-close photos of Saturn's icy moon Rhea, revealing a battered satellite covered in craters from violent impacts.

    Cassini took the amazing new photos of Rhea on March 9 during its fourth and final planned encounter with the Saturn moon. During the encounter, the probe flew within just 620 miles of Rhea, which is Saturn's second-largest satellite. "Take a good, long, luxurious look at these sights from another world, as they will be the last close-ups you'll ever see of this particular moon," Cassini imaging team lead Carolyn Porco, of the Space Science Institute in Boulder, Colo., said in a statement accompanying the photos.

    The flyby was designed primarily to measure Rhea's gravity field, mission scientists said. But Cassini also managed to take 12 pictures of the frigid moon's battered, pockmarked surface, including one that showcases a mysterious long, curving fracture called a graben.

    Rhea is the second-largest of Saturn's 60-odd known moons, with a diameter of 949 miles. It's far smaller than the ringed planet's biggest natural satellite, Titan, which at 3,200 miles across is nearly 50 percent wider than Earth's moon.

    Rhea was discovered in 1672 by the mathematician and astronomer Giovanni Domenico Cassini, who gave his name to the NASA mission currently studying the Saturn system.

    In 2010, researchers determined that the moon has a wispy atmosphere dominated by oxygen and carbon dioxide. The oxygen likely was blasted free from water ice on Rhea's surface by charged particles streaming from Saturn, scientists say, but the origin of the carbon dioxide is more mysterious.

    NASA/JPL-Caltech/Space Science Institute

    This image was taken on March 9, 2013 by NASA's Cassini spacecraft. The camera was pointing toward Rhea at approximately 1,727 miles away.

    The Cassini mission — a joint effort involving NASA, the European Space Agency and the Italian Space Agency — launched in 1997 and arrived at Saturn in 2004. It has been studying the ringed planet and its many moons ever since, and will continue to do so on an extended mission until at least 2017.

    Follow Mike Wall on Twitter @michaeldwall. Follow us @Spacedotcom, Facebook or Google+. Originally published on SPACE.com.

    Copyright 2013 SPACE.com, a TechMediaNetwork company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

  • Venus sparkles in views from Saturn

    NASA / JPL-Caltech / SSI

    The planet Venus sparkles as a bright point of light, seen through the rings of Saturn, in this image from NASA's Cassini orbiter. Venus is the speck just above and to the right of the image's center. The picture was captured on Nov. 10, 2012.

    By Alan Boyle, Science Editor, NBC News


    NASA's Cassini spacecraft has been sending us eye-filling pictures of the giant planet Saturn for almost nine years, but every so often, the camera also sees the small fry of the solar system — such as Venus, which shines in the two latest offerings from the Cassini imaging team.

    One of the photos, captured last November, shows Venus as seen through Saturn's gossamer rings, from a distance of 884 million miles (1.42 billion kilometers, or 9.51 AU). The other picture highlights Venus as a "morning star," hanging just beyond Saturn's edge and next to the giant planet's G ring. Venus was 849 million miles (1.37 billion kilometers, or 9.13 AU) away when that picture was taken in January, according to the imaging team. 

    From such a distance, Venus looks like nothing more than a bright speck. Which isn't surprising, considering that Earth takes on pretty much the same appearance from Saturn, even though it's slightly bigger. The mind-boggling perspectives involved in space vistas led the late astronomer Carl Sagan to call our home planet a "pale blue dot," and I guess that makes Venus a pale yellow dot.

    Venus looks lovely from millions of miles away, but it's not a place you'd want to visit, Carolyn Porco, the leader of the imaging team at the Colorado-based Space Science Institute, said in an email:

    "Along with Mercury, Earth, and Mars, Venus is one of the rocky 'terrestrial' planets in the solar system that orbit relatively close to the sun," she wrote. "It has an atmosphere of carbon dioxide that reaches nearly 900 degrees Fahrenheit (500 degrees Celsius), a surface pressure 100 times that of Earth's, and is covered in thick, white sulfuric acid clouds, making it very bright. Despite a thoroughly hellish environment that would melt lead, Venus is considered a twin of our planet because of their similar sizes, masses, rocky compositions and close orbits.

    "Think about Venus the next time you find yourself reveling in the thriving flora, balmy breezes, and temperate climate of a lovely day on Earth, and remember: You could be somewhere else!"

    NASA / JPL-Caltech / SSI

    Dawn on Saturn is greeted across the vastness of interplanetary space by the morning star, Venus, in this image from Cassini. Venus appears just off the edge of the planet, in the upper part of the image, directly above the white streak of Saturn's G ring. Lower down, Saturn's E ring makes an appearance. A bright spot near the E ring is a distant star. This picture was captured on Jan. 4, at a distance of about 371,000 miles (597,000 kilometers) from Saturn.

    Slideshow: Best of Cassini

    The Cassini spacecraft is sending back unprecedented imagery of Saturn, its rings and its moons. Click "Launch" to see some of the greatest hits from the Cassini mission.

    Launch slideshow

    More about Saturn and Venus:

    Slideshow: Month in Space

    Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. To keep up with Cosmic Log as well as NBCNews.com's other stories about science and space, sign up for the Tech & Science newsletter, delivered to your email in-box every weekday. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

  • Solar particles seen moving at incredible speeds near Saturn

    ESA

    This artist's impression shows NASA's Cassini spacecraft exploring the magnetic environment of Saturn. Saturn's magnetosphere is depicted in gray, while the complex bow shock region — the shock wave in the solar wind that surrounds the magnetosphere — is in blue. The image is not to scale.

    By Mike Wall
    Space.com

    NASA's Cassini spacecraft has spotted solar particles moving at incredible speeds near Saturn, giving scientists a rare up-close look at phenomena that occur during dramatic star explosions.

    The particles flowed from the sun during a strong blast of solar wind, then plowed into Saturn's magnetic field shortly thereafter. This encounter, which Cassini observed in February 2007, created a shockwave that accelerated the particles to super-high energies, scientists said.

    Similar shockwaves commonly form in the aftermath of massive star explosions called supernovas, ramping up nearby particles to nearly the speed of light. Researchers think supernova shockwaves are the primary source of cosmic rays, high-energy particles that pervade our Milky Way galaxy and slam into Earth's atmosphere continuously.

    It can be tough to study distant supernovas and their shockwaves, so Cassini's observations provide a welcome proxy, scientists said.

    "Cassini has essentially given us the capability of studying the nature of a supernova shock in situ in our own solar system, bridging the gap to distant high-energy astrophysical phenomena that are usually only studied remotely," Adam Masters, of the Institute of Space and Astronautical Science, Sagamihara, Japan, said in a statement.

    Masters is lead author of a study reporting the Cassini findings, which was published this week in the journal Nature Physics.

    The Saturn shockwave may be the most powerful ever detected at the ringed planet and suggests that certain kinds of shocks can be surprisingly efficient particle accelerators, researchers said.

    The $3.2 billion Cassini mission is a joint effort of NASA, the European Space Agency and the Italian Space Agency. Cassini launched in 1997 and arrived at the Saturn system in 2004, delivering a lander called Huygens to the planet's huge moon Titan in January 2005.

    Cassini will continue studying the ringed planet and its many moons for several years to come; Cassini's mission has been extended through at least 2017.

    Follow Space.com senior writer Mike Wall on Twitter @michaeldwall or Space.com @Spacedotcom. We're also on Facebook and Google+. 

    Copyright 2013 Space.com, a TechMediaNetwork company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

  • Saturn's moons and rings mix it up

    NASA / JPL-Caltech / SSI

    Saturn's rings stretch in front of the moons Titan and Tethys in a Dec. 7 image captured by NASA's Cassini orbiter.

    By Alan Boyle, Science Editor, NBC News



    What do you get when you cross the rings and moons of Saturn? That sounds like the set-up for a joke, but for the team that processes the pictures from NASA's Cassini orbiter, the answer is totally serious: You get stunning images of the moons' interplay with the giant planet's rings.

    The picture above, released today, shows Saturn's rings nearly edge-on, in front of the moons Titan (left) and Tethys (right). Cassini's narrow-angle camera captured the view on Dec. 7, 2011, as it was flying by a distance of about 1.4 million miles from icy Tethys (TEETH-iss) and 1.9 million miles from smog-covered Titan.

    Last week the Cassini imaging team released another stunner snapped on the same day, showing tiny Tethys (660 miles wide) near the center of Saturn's disk, just below the ring plane.

    Cassini was so close to Saturn's equator that the rings look like little more than a straight line, but you can see the delicate shadows of the rings stretching across the planet's sunlit disk into darkness. When Cassini's wide-angle camera took this picture, Tethys was about 1.1 million miles away.

    Saturn, with a diameter of 74,900 miles, overwhelms Tethys in size. But the gas giant's density is such that it could float in water — that is, if there were a body of water big enough for it to float in. Does that mean Saturn could take a bath? Yes ... but it might leave a ring.

    NASA / JPL-Caltech / SSI

    The Saturnian moon Tethys is dwarfed by the ringed planet's disk in this Dec. 7 picture from the Cassini orbiter.

    More imagery from Cassini and other space probes:

    Alan Boyle is msnbc.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter or adding the Cosmic Log Google+ page to your circles. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for other worlds.