Hexagon Formation on Saturn

Cassini Images Bizarre Hexagon on Saturn

Pasadena, Calif. — An odd, six-sided, honeycomb-shaped feature circling the entire north pole of Saturn has captured the interest of scientists with NASA’s Cassini mission.

NASA’s Voyager 1 and 2 spacecraft imaged the feature over two decades ago. The fact that it has appeared in Cassini images indicates that it is a long-lived feature. A second hexagon, significantly darker than the brighter historical feature, is also visible in the Cassini pictures. The spacecraft’s visual and infrared mapping spectrometer is the first instrument to capture the entire hexagon feature in one image.

six-sided feature at Saturn's north pole Image right: This nighttime view of Saturn’s north pole shows a bizarre six-sided hexagon feature encircling the entire north pole. The red color indicates the amount of 5-micron wavelength radiation, or heat, generated in the warm interior of Saturn that escapes the planet. Image credit: NASA/JPL/University of Arizona

“This is a very strange feature, lying in a precise geometric fashion with six nearly equally straight sides,” said Kevin Baines, atmospheric expert and member of Cassini’s visual and infrared mapping spectrometer team at NASA’s Jet Propulsion Laboratory, Pasadena, Calif. “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.”

The hexagon is similar to Earth’s polar vortex, which has winds blowing in a circular pattern around the polar region.  On Saturn, the vortex has a hexagonal rather than circular shape. The hexagon is nearly 25,000 kilometers (15,000 miles) across. Nearly four Earths could fit inside it.

The new images taken in thermal-infrared light show the hexagon extends much deeper down into the atmosphere than previously expected, some 100 kilometers (60 miles) below the cloud tops. A system of clouds lies within the hexagon. The clouds appear to be whipping around the hexagon like cars on a racetrack.

“It’s amazing to see such striking differences on opposite ends of Saturn’s poles,” said Bob Brown, team leader of the Cassini visual and infrared mapping spectrometer, University of Arizona, Tucson. “At the south pole we have what appears to be a hurricane with a giant eye, and at the north pole of Saturn we have this geometric feature, which is completely different.”

Spinning Saturn Image left: This nighttime movie of the depths of the north pole of Saturn reveals a dynamic, active planet lurking underneath the ubiquitous cover of upper-level hazes. Image credit: NASA/JPL/University of Arizona
+ Full movie and caption

The Saturn north pole hexagon has not been visible to Cassini’s visual cameras, because it’s winter in that area, so the hexagon is under the cover of the long polar night, which lasts about 15 years. The infrared mapping spectrometer can image Saturn in both daytime and nighttime conditions and see deep inside. It imaged the feature with thermal wavelengths near 5 microns (seven times the wavelength visible to the human eye) during a 12-day period beginning on Oct. 30, 2006. As winter wanes over the next two years, the feature may become visible to the visual cameras.

Based on the new images and more information on the depth of the feature, scientists think it is not linked to Saturn’s radio emissions or to auroral activity, as once contemplated, even though Saturn’s northern aurora lies nearly overhead.

six-sided feature encircling the north pole of SaturnImage right: Another view of the bizarre six-sided feature encircling the north pole of Saturn. Image credit: NASA/JPL/University of Arizona
+ Full image and caption

The hexagon appears to have remained fixed with Saturn’s rotation rate and axis since first glimpsed by Voyager 26 years ago. The actual rotation rate of Saturn is still uncertain.

“Once we understand its dynamical nature, this long-lived, deep-seated polar hexagon may give us a clue to the true rotation rate of the deep atmosphere and perhaps the interior,” added Baines.

The hexagon images and movie, including the north polar auroras are available at: http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov and http://wwwvims.lpl.arizona.edu .

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA’s Science Mission Directorate, Washington. The Cassini orbiter was designed, developed and assembled at JPL. The Visual and Infrared Mapping Spectrometer team is based at the University of Arizona.

from:     http://www.nasa.gov/mission_pages/cassini/media/cassini-20070327.html

Planets & Pyramids

Three Planets above Egyptians Pyramids on December 3, 2012?


Tonight for December 3, 2012

Here’s the exact configuration of the planets Mercury, Venus and Saturn on the morning of December 3, 2012, as seen from the site of the Giza pyramids in Egypt.

Venus, Saturn and Mercury are all in the predawn sky in early December 2012, but not exactly in the way that a widely circulated image on the Internet shows them. Instead, on December 3, 2012, they’ll look like the chart at right, as seen from the site of the three pyramids in the Giza Necropolis bordering what is now El Giza, Egypt. Will Mercury, Venus and Saturn be close together in the predawn sky in early December? Yes. Does this configuration happen only every 2,737 years? Well, we’re not sure what’s meant by that. The planets appear near each other all the time – constantly – as seen from Earth’s vantage point, as they and we orbit the sun. Mercury, Venus and Saturn were together in the sky last in 2005.

Will Mercury, Venus and Saturn appear as this photo shows, over the Egyptian pyramids? No. Not sure how this planet-pyramid story started circulating, but it’s possible someone noticed (or searched for) a true sky event in December 2012 (peak month of 2012 doomsday hype) and then manufactured the false images below. The images were made before the event happened, so we know the images below are photoshopped illustrations.

THIS WILL NOT HAPPEN ON DECEMBER 3, 2012. The image is an exaggeration of a true, and common, sky event.

Here’s another version of the photoshopped illustration, showing three planets above pyramids at Giza on December 3, 2012. This image, too, is an exaggeration of a common sky event.

What’s happening with the planets Venus, Mercury and Saturn in December 2012? Nothing unusual. Venus is shining before dawn. It has been shining before dawn since June 2012. Remember the cool Venus transit in early June 2012? That’s when Venus crossed from the evening to the morning sky. As the innermost planet, Mercury always appears either before dawn or after sunset. It shifts from place to place half a dozen times each earthly year. So if Venus is up before dawn, Mercury is bound to be near it at times. Saturn, too, returns to the predawn sky at least once every year. Why? Because Earth orbits the sun once a year. So our own motion in orbit places Saturn on a yearly cycle in our sky.

What’s cool about what’s happening on December 3, 2012 is that these three planets will be equidistant from each other. Will they be exactly above three Egyptian pyramids as shown in the illustrations above? No. But someone standing in just the right spot near these pyramids should be able to get the planets to appear above the pyramids in a picturesque way. For sure, if you stand in a particular spot near the pyramids – facing them, and facing the eastern sky before dawn – you should be able to see the planets and the pyramids together. That would be a nice thing to see! If anyone gets a photo of this, please drop us a note via the Contact button at the top of this page, or post it directly to EarthSky’s Facebook page.

Here’s the real thing. Mercury, Venus and Saturn as seen December 2, 2012 over Oslofjord, an inlet in southeast Norway, by EarthSky Facebook friend Jann Peter Normann. Thank you, Jann Peter! We know you can see Venus. Look closely for Mercury (lower left) and Saturn (upper right). View larger.

What’s puzzling about this Mercury-Venus-Saturn-pyramid story is that there was a much better display of two planets earlier this year. In March 2012, the two brightest planets – Venus and Jupiter – had a dazzling conjunction in the evening sky. Someone standing in just the right spot in March could have captured a great photo of Venus and Jupiter above the pyramids of Giza. So why did the perpetrators of the photoshopped images above choose Mercury-Venus-Saturn instead to portray, instead of Venus and Jupiter? Not sure. Venus and Jupiter were much more spectacular than Mercury-Venus-Saturn will be!

Why do these planets appear in a line in the predawn sky right now? The planets in our solar system all orbit the sun in a nearly flat plane. So – whenever we see planets near each other in our sky – they always appear in a graceful line across our sky. This line across our sky is the same one traveled by the sun in the course of a day. It’s the same path traveled by the moon. Why? Because most objects in our solar system orbit in this flat plane of the solar system. Of course, this pathway across our sky has a special name. It’s called the ecliptic. Read more about the ecliptic here.

These widely circulating images of Mercury, Venus and Saturn above the Egyptian pyramids reminds us of the false image of India at the 2012 Diwali festival. People love to take real events or images and manufacture something exaggerated from them. Why? We don’t know.

The moon will sweep past the planets in the morning sky beginning around December 10, 2012. That will be cool to see!

By the morning of December 11, the moon will be closer to Venus. Catch the planets and moon on these mornings! They’ll be much more beautiful than any image of them can convey.

The good news for skywatchers is that Saturn and Venus are now making it easy for us to find Mercury, which, as the innermost planet of the solar system, moves from place to place in the sky so often that you might be likely to miss it. To see these planets, find an unobstructed eastern horizon and get up about 90 minutes before sunrise. Look low in the eastern sky for dazzling Venus, the brightest star-like light in the morning sky. Saturn shines a short hop above Venus and Mercury a short hop below. A line from Saturn through Venus points out Mercury’s place on or near the horizon. If you can’t see Mercury with the eye alone, try binoculars.

It rarely gets any easier than this for seeing Mercury in the Northern Hemisphere. Mercury reaches its greatest elongation west of the sun on Tuesday, December 4. That means this often hard-to-see world is climbing above the southeast horizon a maximum time before sunrise. Given a level and unobstructed horizon, Mercury rises about one and three-quarter hours before the sun at mid-northern latitudes, and about an hour before sunup at middle latitudes in the Southern Hemisphere.

Rising times of the sun and morning planets in your sky

Mercury shines as brilliantly as a first-magnitude star. The innermost planet isn’t hard to see because it’s dim. It’s because – as seen from Earth – this world stays perpetually close to the sun, so it’s often lost in the twilight glare. But with Mercury swinging to its farthest point west of the sun, before sunrise tomorrow is about as good as it gets for catching Mercury in the morning sky.

No, that’s not the moon! It’s Mercury, the innermost and smallest planet of the solar system. Image via Messenger

Our chart at top shows the sky scene for about one hour before sunrise at North American mid-northern latitudes. But it’d be better to get up sooner if you can, using Saturn and Venus to catch this elusive world just as darkness gives way to dawn. Look first for Venus and then Saturn up above. If you don’t see Mercury on line with Saturn and Venus, wait a little while as Mercury may still be below the horizon.

December 2012 guide to the five visible planets

Don’t fret if you miss Mercury tomorrow. Keep using Saturn and Venus to locate Mercury near the horizon, for the innermost planet will reign as a morning “star” for another two to three weeks!

Bottom line: Will Venus, Saturn and Mercury appear above Egyptian pyramids in early December 2012, as a widely circulated image on the Internet suggests? Well, it’s true they’re all together in the eastern, predawn sky. That’s a fairly common event. But the images being circulated – showing them above the pyramids – are an exaggeration of a true sky event. The good news: these planets will be beautiful in early December! If you watch the night sky on a regular basis, you know it conveys a profound beauty and order every day of the year. And if you’re lucky enough to observe them from the Egyptian pyramids, hey, we envy you!

from:    http://earthsky.org/tonight/saturn-venus-and-mercury-line-up-before-dawn-december

Titan’s Arrow

What Caused a Giant Arrow-Shaped Cloud On Saturn’s Moon Titan?

ScienceDaily (Aug. 15, 2011) — Why does Titan, Saturn’s largest moon, have what looks like an enormous white arrow about the size of Texas on its surface?

A research group led by Jonathan L. Mitchell, UCLA assistant professor of earth and space sciences and of atmospheric and oceanic sciences, has answered this question by using a global circulation model of Titan to demonstrate how planetary-scale atmospheric waves affect the moon’s weather patterns, leading to a “stenciling” effect that results in sharp and sometimes surprising cloud shapes.

“These atmospheric waves are somewhat like the natural, resonant vibration of a wine glass,” Mitchell said. “Individual clouds might ‘ring the bell,’ so to speak, and once the ringing starts, the clouds have to respond to that vibration.”

The fascinating clouds, including arrow-shaped ones, that result from the atmospheric waves can cause intense precipitation — sometimes more than 20 times Titan’s average seasonal rainfall — and could be essential in shaping Titan’s surface by erosion

to read more, go to:    http://www.sciencedaily.com/releases/2011/08/110815194403.htm