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Saturn: the "Ringed Beauty" and His Moons
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SaturnianSpace-EB2.gifViews and Features of the Space of Saturn (GIF-Movie; credits: Elisabetta Bonora - Lunexit Team)54 visitenessun commentoMareKromium
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SaturnianSpace-EB3.gifViews and Features of the Space of Saturn (Edited GIF-Movie; credits: Elisabetta Bonora - Lunexit Team)54 visitenessun commentoMareKromium
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SaturnianSpace-MF.gifStars, Streaks and (overexposed) Moons in the Space of Saturn (GIF-Movie; credits: Dr M. Faccin - Lunexit Team)54 visitenessun commentoMareKromium
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SaturnianSpace-RB1.gifViews and Features of the Space of Saturn (GIF-Movie; credits: Elisabetta Bonora - Lunexit Team)54 visitenessun commentoMareKromium
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Saturnian_Inner_Moons-PIA13423.jpgThe (enhanced) "True Colors" of the Saturninan Inner Moons80 visiteThis set of enhanced-color maps made from data obtained by NASA's Cassini Spacecraft show Saturn's moons Mimas, Enceladus, Tethys, Dione and Rhea. The global maps show the colorful splotches and bands on the icy moons' Surfaces that scientists believe came from bombardments large and small.
Icy material sprayed by Enceladus, which makes up the misty E-Ring around Saturn, appears to leave a brighter, blue signature.
The pattern of bluish material on Enceladus, for example, indicates that the moon is covered by the fallback of its own "breath". Enceladean spray also appears to splatter the parts of Tethys, Dione and Rhea that run into the spray head-on in their orbits around Saturn. But scientists are still puzzling over the reason why the Enceladean Frost on the Leading Hemisphere of these moons bears a coral-colored, rather than bluish, tint.
On Tethys, Dione and Rhea, darker, rust-colored reddish hues paint the entire Trailing Hemisphere, or the side that faces backward in the orbit around Saturn. The reddish hues are thought to be caused by tiny particle strikes from circulating Plasma, a gas-like state of matter so hot that atoms split into an ion and an electron, in Saturn's magnetic environment. Tiny, iron-rich "nanoparticles" may also be involved, based on earlier analyses by the Cassini Visual and InfraRed Mapping Spectrometer Team.
Mimas is touched by the tint of Enceladean spray, but it appears on the trailing side of Mimas. This probably occurs because it orbits inside the path of Enceladus, or closer to Saturn, than Tethys, Dione and Rhea.
Mimas and Tethys also sport a dark, bluish band.
The bands match patterns one might expect if their Surface were being irradiated by high-energy electrons that drift in a direction opposite to the flow of Plasma in the magnetic bubble around Saturn. Scientists are still figuring out exactly what is happening on Mimas, but the electrons appear to be zapping the Surface in a way that matches the Pac-Man pattern detected by Cassini's Composite InfraRed Spectrometer.
On Rhea, a unique chain of bluish splotches appears where fresh, bluish ice has been exposed on older crater rims. Cassini imaging scientists recently reported that they did not see evidence in Cassini images of a ring around Rhea. However, scientists analyzing these new enhanced-color maps suggest the crash of orbiting material, perhaps a ring, to the surface of Rhea in the not too distant past, could explain the bluish splotches.
These new maps were made by processing raw images obtained by Cassini's imaging cameras from 2004 to 2009. Scientists analyzed frames shot through Visible-Light, UltraViolet and InfraRed filters. The processing enhanced our views of these moons beyond what could be seen by the human eye.
The maps are in a simple cylindrical projection from 90° South Latitude (bottom) to 90° North Latitude (top). From left to right, they cover 360° to - 2° West Longitude. The Leading Hemisphere appears on the right side of each map and Trailing Hemisphere appears on the left.MareKromium
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Saturnian_Lightnings-00.jpgSaturnian Storm and Lightnings (CTX Frame - credits: NASA/JPL/SSI)132 visiteA powerful lightning storm brewing in Saturn's atmosphere since January has become the solar system's longest continuously observed thunderstorm, astronomers have announced.
The storm breaks the record duration of 7,5 months set by another thunderstorm observed on Saturn by NASA's Cassini Spacecraft between November 2007 and July 2008. The current thunderstorm on Saturn is the ninth that has been measured since Cassini swung into orbit around Saturn in July 2004.
Lightning discharges in Saturn's Atmosphere emit very powerful radio waves, which are measured by the antennas and receivers of the Cassini Radio and Plasma Wave Science (RPWS) instrument. The radio waves are about 10.000 times stronger than their terrestrial counterparts and originate from huge thunderstorms in Saturn's Atmosphere with diameters of about 1900 miles (3057,746 Km).
The observations of this latest thunderstorm will be presented by Georg Fischer of the Austrian Academy of Sciences at the European Planetary Science Congress in Potsdam, Germany, on Sept. 15. "These lightning storms are not only astonishing for their power and longevity, the radio waves that they emit are also useful for studying Saturn's Ionosphere, the charged layer that surrounds the planet a few thousand kilometers above the cloud tops," Fischer said. "The radio waves have to cross the Ionosphere to get to Cassini and thereby act as a natural tool to probe the structure of the layer and the levels of ionization in different regions."
Results from Cassini's RPWS instrument have confirmed previous studies of the Voyager spacecraft indicating that levels of ionization are approx. 100 times higher on the day-side than the night side of Saturn's Ionosphere.
Lightning storms on Saturn usually occur in a region that nicknamed "Storm Alley" by scientists. The region lies 35° South of Saturn's Equator.
"The reason why we see lightning in this peculiar location is not completely clear," Fischer said. "It could be that this latitude is one of the few places in Saturn's Atmosphere that allow large-scale vertical convection of water clouds, which is necessary for thunderstorms to develop. However, it may be a seasonal effect. Voyager observed lightning storms near the Equator, so now that Saturn has passed its Equinox on Aug. 11, we may see the storms move back to Equatorial Latitudes."
The lightning's presence was confirmed in another way: During Cassini's last close flyby of Titan on Aug. 25, Cassini's view of Saturn was obscured by Titan for a half-hour, and no lightning was observed. "Although we know from Cassini images where Saturn lightning comes from, this unique event was another nice proof for their origin," Fischer also said.MareKromium
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Saturnian_Lightnings-01.jpgSaturnian Storm and Lightnings (EDM - credits: NASA/JPL/SSI)133 visiteA monster storm spawning bolts of lightning 10.000 times more powerful than any seen on Earth is raging on the Ringed Planet Saturn.
The powerful electrical storm cropped up in Saturn's Southern Hemisphere five months ago, when it was first spotted by NASA's Cassini Spacecraft, and has persevered to become the Planet's longest continuously recorded tempest to date.
"We saw similar storms in 2004 and 2006 that each lasted for nearly a month, but this storm is longer-lived by far, said Georg Fischer, an associate with Cassini's radio and plasma wave science team at the University of Iowa, Iowa City, in a statement. And it appeared after nearly two years during which we did not detect any electrical storm activity from Saturn."
Cassini's radio and plasma wave science instrument first picked up signals from the storm's lightning bursts on Nov. 27, 2007, with the probe's cameras catching their first visual glimpse on Dec. 6. Images of the storm show it as a smudge on Saturn's otherwise creamy cloud bands.
"The electrostatic radio outbursts have waxed and waned in intensity for five months now," Fischer said.
Electrical storms on Saturn are similar to thunderstorms on Earth, but much larger. They can span thousands of miles and generate radio bursts from lightning that can be thousands of times more powerful than Earthly lightning bolts, said mission scientists, who named a massive lightning storm in 2004 "Dragon".
The current electrical tempest is mired in a region of Saturn that mission scientists have dubbed "Storm Alley" because of its frequent and intense storms. Every few seconds the storm belches intense radio pulses consistent with lightning that can be detected even when the weather itself is over the horizon and out of direct view from Cassini.
Researchers hope that by tracking the Saturnian weather, they may gain new insights into the processes behind the Planet's lightning, as well as how it changes as the seasons shift from Summer to Autumn in Saturn's Southern Hemisphere.
In order to see the storm, the imaging cameras have to be looking at the right place at the right time, and whenever our cameras see the storm, the radio outbursts are there," said Ulyana Dyudina, a Cassini imaging team associate at the California Institute of Technology in Pasadena, Calif.
Cassini's onboard instruments have tracked the storm every 10 hours and 40 minutes, when Saturn's rotation brings it into view, though amateur astronomers are also watching over the tempest from Earth.
"Since Cassini's camera cannot track the storm every day, the amateur data are invaluable," said Fischer. "I am in continuous contact with astronomers from around the world."
Launched in 1997, Cassini arrived at Saturn in 2004 and has spotted a series of odd storms while studying the Ringed Planet and its many moons. The probe has captured views of a hurricane-like storm near the South Pole of Saturn and recorded a massive lightning storm about 2175 miles wide (3500,3145 Km) wide in 2006.MareKromium
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Saturnian_Lightnings-02.jpgSaturnian Storm and Lightnings (EDM - credits: NASA/JPL/SSI)161 visiteScientists are tracking the strongest lighting storm ever detected at Saturn. The storm is larger than the continental United States, with electrical activity about 1000 times stronger than the lightning on Earth. Radio outbursts were first detected by NASA's Cassini Spacecraft on Jan. 23. The storm is about 2175 miles wide (approx. 3500 Km). "It's really the only large storm on the whole planet," said Andrew Ingersoll, a member of the Cassini imaging team.
Earth-based amateur astronomers were able view Saturn's dayside with their telescopes when Cassini could not. The amateurs' images of Saturn provided the first visual confirmation of the storm.
The storm is in a Region of the Southern Hemisphere referred to as "Storm Alley" by scientists because of the high level of storm activity observed there. The latitude of the new storm matches that of the "Dragon Storm", which was a powerful emitter of radio noise and was imaged by Cassini in 2004. It may be a reemergence of that storm or a new storm, scientists said.
Sunlight reflected from Saturn's Rings (called "Ringshine") provided illumination needed to allowing the storm and other cloud features to be seen in a new Cassini image.MareKromium
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Saturnian_Lightnings-03.jpgSaturnian Lightnings146 visiteNASA's Cassini Spacecraft captured images of lightning at Saturn that allowed scientists to create the first movie showing lightning flashing on another Planet.
"The Visible Light images tell us a lot about the lightning," said Ulyana Dyudina, a Cassini imaging team associate based at the California Institute of Technology (Caltech) in Pasadena, Calif., who was the first to see the flashes. "Now we can begin to measure how powerful these storms are, where they form in the cloud layer and how the optical intensity relates to the total energy of the thunderstorms."
After waiting years for Saturn to dim enough for the Spacecraft's cameras to be able to detect bursts of light, scientists were able to create the movie, complete with an accompanying soundtrack that features the crackle of radio waves emitted when lightning bolts struck.
"This is the first time we have the visible lightning flash together with the radio data," said Georg Fischer, a radio and plasma wave science team associate based at the Space Research Institute in Graz, Austria. "Now that the radio and visible light data line up, we know for sure we are seeing powerful lightning storms."
Cassini, launched in 1997, and NASA's Voyager mission, launched in 1977, had previously captured radio emissions from storms on Saturn.
A belt around the gas giant, where Cassini previously detected radio emissions and bright, conservative clouds, even earned the nickname "storm alley." Cassini's cameras, however, had been unable to obtain pictures of lightning flashing.
Since the Robotic Spacecraft's arrival at Saturn in 2004, it has been difficult for Cassini to see lightning because the planet is very bright and reflective. Sunlight that shines off of Saturn's enormous Rings makes even the night side of Saturn brighter than a full-moon night on Earth.
The Equinox period around August 2009 finally brought enough darkness needed for Cassini's cameras. During Equinox, the Sun shone directly over the Planet's Equator, lighting the Rings edge-on only, leaving the bulk of the Rings in shadow.
The movie and radio data collected by the scientists suggest extremely powerful storms, with lightning that flashes as brightly as the brightest super-bolts of lightning on Earth, according to Andrew Ingersoll, a Cassini imaging science subsystem team member at Caltech.
"What's interesting is that the storms are as powerful or even more powerful at Saturn as on Earth," Ingersoll said. "But they occur much less frequently, with usually only one happening on the planet at any given time, though it can last for months."
The first images of lightning on Saturn were captured in August 2009, during a storm that lasted from January to October 2009, longer than any other observed lightning storm in the Solar System.
In order to make a video, scientists needed more pictures with brighter lightning and strong radio signals. Data collected during a shorter subsequent storm, which occurred from November through mid-December 2009, was also used.
The frames in the video were obtained over a period of 16 minutes on Nov. 30, 2009. The flashes lasted less than one second. The images also show a cloud as long as 1900 miles (3057,746 Km) across, with the regions illuminated by the lightning flashes reaching approx. 190 miles (305,7746 Km) in diameter. Scientists used the width of the lightning flashes to gauge the depth of the bolts below the cloud tops.
Lightning that strikes on Earth and Saturn emit radio waves at a frequency that can cause static on an AM radio. The audio in the video approximate that static sound, based on Saturn's electrostatic discharge signals that were detected by Cassini's radio and plasma wave science instrument.
Scientists monitoring the Cassini Orbiter were busy during this Equinox period, having already observed clumps in Saturn's Rings that are as high as the Rocky Mountains.
The Cassini-Huygens mission is a joint project involving NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of Caltech, manages the Cassini-Huygens mission for NASA's Science Mission Directorate in Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at the Jet Propulsion Laboratory.MareKromium
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Saturnian_Sky-N00166739-47-EB-LXTT.jpgSaturnian Sky (Superdefinition - credits for the additional process.: Elisabetta Bonora - Lunexit Team)55 visitenessun commentoMareKromium
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Saturnian_Sky.gifIn the Sky of Saturn (GIF-Movie; credits: Dr M. Faccin)54 visitenessun commentoMareKromium
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Saturnian_Space-N00156094-N00156177.gifCosmic Shower (GIF-Movie; credits: Dr Gianluigi Barca - Lunexit Team)54 visitenessun commentoMareKromium
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