[Moogs]

I didn't think vortices had sides.

[Kickaha]

Read the article. That's the neat part.

Stable vortices that aren't round, but polygonal.

[billybobsky]

Originally Posted by Kickaha Naw. It's a REALLY HUGE example of a steadystate polygonal vortex. http://www.physorg.com/news66924222.html

Probably due to a smooth solid like core rotating much much faster than the clouds above...

[drewprops]

HOLY MOLY!!!!
That hexagon is bigger than three Earths!!!

[Kickaha]

Originally Posted by billybobsky Probably due to a smooth solid like core rotating much much faster than the clouds above...

Yeah, I love that the running theory is that it is tidal-locked with the core at a 10+hr period, when according to the polygonal vortex experiment, that core should be frickin' flying.

[curiousuburb]

But this story on Enceladus outgassing getting ionized and apparently borking the rotation of the magnetic field implies that we still don't know the actual rotation period of Saturn itself.

Originally Posted by Cassini Enceladus Geysers Mask the Length of Saturn's Day March 22, 2007 (Source: Jet Propulsion Laboratory) In a David and Goliath story of Saturnian proportions, the little moon Enceladus is weighing down giant Saturn's magnetic field so much that the field is rotating slower than the planet. This phenomenon makes it nearly impossible to measure the length of the Saturn day using techniques that work at the other giant planets. <--- Not to scale, obviously Geysers on Saturn's little moon Enceladus are throwing off Saturn's internal clock, making it hard to measure the length of the Saturn day. Hear Sounds from Saturn "No one could have predicted that the little moon Enceladus would have such an influence on the radio technique that has been used for years to determine the length of the Saturn day," said Dr. Don Gurnett of the University of Iowa, Iowa City. Gurnett is the principal investigator on the radio and plasma wave science experiment onboard NASA's Cassini spacecraft. The radio technique measures the rotation of the planet by taking its radio pulse rate -- the rhythm of natural radio signals from the planet. A new study of Cassini data reported this week in the online version of the journal Science determined that Saturn's magnetic field lines, invisible lines originating from the interior of a magnetized planet, are being forced to slip relative to the rotation of the planet by the weight of electrically charged particles originating from geysers spewing water vapor and ice from Enceladus. These results are based on joint observations by two Cassini instruments -- the radio and plasma wave instrument and the magnetometer. The neutral gas particles ejected from the geysers on Enceladus form a donut-like torus around Saturn. As these particles become electrically charged, they are captured by Saturn's magnetic field, forming a disk of ionized gas, or plasma, which surrounds the planet near the equator. The particles weigh down the magnetic field so much that the rate of rotation of the plasma disk slows down slightly. This slippage causes the radio period, controlled by the plasma disk rotation, to be longer than the planet's actual rotation period. Scientists conclude the period Cassini has been measuring from radio emission is not the length of the Saturn day, but rather the rotation period of the plasma disk. At present, because of Saturn's cloud motion, no technique is known that can accurately measure the planet's actual internal rotation. Finding out the length of Saturn's day has been a challenge because the gaseous planet has no surface or fixed point to clock its rotation rate. Initially, the approach was to use periodic regular radio signals, as has been done for Jupiter, Uranus and Neptune. However, Saturn's radio period has turned out to be troubling in two ways. It seems to be a pulsed signal rather than a rotating, lighthouse-like beam. Secondly, the period seems to be slowly changing over months to years. The day measured by Cassini is some six minutes longer than the day recorded by NASA's Voyager spacecraft in the early 1980s, a change of nearly 1 percent. "We have linked the pulsing radio signal to a rotating magnetic signal. Once each rotation of Saturn's magnetic field, an asymmetry in the field triggers a burst of radio waves," said Dr. David Southwood, co-author, Imperial College London, and director of science at the European Space Agency. "We have then linked both signals to material that has come from Enceladus." Based on the new observations, scientists now think there are two possible reasons for the change in radio period. The first theory is that the geysers on Enceladus could be more active now than in Voyagers' time. The second is that there may be seasonal variations as Saturn orbits the sun once every 29 years. "One would predict that when the geysers are very active, the particles load down the magnetic field and increase the slippage of the plasma disk, thereby increasing the radio emission period even more. If the geysers are less active, there would be less of a load on the magnetic field, and therefore less slippage of the plasma disk, and a shorter period," said Gurnett. "The direct link between radio, magnetic field and deep planetary rotation has been taken for granted up to now. Saturn is showing we need to think further," said Michele Dougherty, principal investigator on Cassini's magnetometer instrument, Imperial College London. The Saturn radio emissions detected by Cassini have been converted into an audio file available at: http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov .

[Moogs]

That is bad-ass, I must say...

Also I caught part of a show on M-theory last night where they've apparently decided it's possible that the big-bang was nothing more than the "membranes" of two parallel universes touching at a specific point, as a result of "ripples" or waves. And that therefore time does not have to halt at the big bang but can keep on tracking backwards, and that also there are possibly countless such universal planes, floating around out there...

...because you know this cosmological stuff isn't mind-boggling enough already! We need to be more baffled!

[Moogs]

Thought I would borrow your thread for a bit... seems we'd better get cracking on the NGT and near-light-speed propulsion. There may now be a destination about 20 light years away, in case we need to start a human colony outside earth. Maybe in 60 or 70 years the technology will exist to contemplate going there. Assuming there are no locals and assuming if there are, that we're welcome. I know I wouldn't invite us over for dinner.

[curiousuburb]

Two new stunners from the spacecraft. Next Titan Flyby under 9 days.

Originally Posted by Cassini An Icy Composition May 4, 2007 Full-Res: PIA08933 The Cassini spacecraft looks across Saturn's cloud-dotted north and shadowed pole, and out across the lanes of ice that compose its rings. Prometheus (102 kilometers, or 63 miles across) is visible between the A and F rings near the center of the image. This view looks toward the unilluminated side of the rings from about 42 degrees above the ringplane. The planet's shadow stretches toward the lower right corner. The image was taken in visible light with the Cassini spacecraft wide-angle camera on April 1, 2007 at a distance of approximately 2 million kilometers (1.2 million miles) from Saturn. Image scale is 119 kilometers (74 miles) per pixel. My Blue Heaven May 3, 2007 Full-Res: PIA08932 In Saturn's bluish north, day ends for the dreamy white clouds that stretch here into twilight. This natural color scene shows middle latitudes in Saturn's north at excellent resolution, and with little detectable blur due to spacecraft motion. North on Saturn is up and rotated 22 degrees to the right. Images taken using red, green and blue spectral filters were combined to create this color view. The image was taken with the Cassini spacecraft narrow-angle camera on April 1, 2007 at a distance of approximately 2 million kilometers (1.2 million miles) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 86 degrees. Image scale is about 12 kilometers (7 miles) per pixel.

[Moogs]

Man... that is one mind-bogglingly large planet. Hard to believe there's nothing under there but gas and a metallic core.

[curiousuburb]

Huygens discovers evidence of hidden ocean on Titan

Originally Posted by ESA Titan’s mysterious radio wave Titan's full disk 1 June 2007 Huygens scored a first in 2005 by measuring the electrical conductivity of Titan’s atmosphere. The results hint at a new way to investigate the subsurface layers of Titan and could provide insight into whether or not Titan has a subsurface ocean. The Permittivity, Waves and Altimetry (PWA) sensor on the Huygens Atmosphere Structure Instrument (HASI) detected an extremely low frequency (ELF) radio wave during the descent. It was oscillating very slowly for a radio wave, just 36 times a second, and increased slightly in frequency as the probe reached lower altitudes. If the PWA team confirms that the signal is a natural phenomenon and not an artefact of the way the instrument worked, they will have discovered a powerful new way to probe not just the atmosphere of Titan but its subsurface as well. The only other world on which ELF waves were detected before was Earth. They are reflected by both the surface of the Earth and its ionosphere, the rarefied region of the atmosphere where most particles are electrically charged. This turns the atmosphere into a giant ‘sound box’ where certain frequencies of ELF waves resonate and are reinforced, whilst other die away. On Titan, however, the surface is a poor reflector because of its low conductivity and so these waves penetrate the interior. “The wave could have been reflected by the liquid-ice boundary of a subsurface ocean of water and ammonia predicted by theoretical models,” says Fernando Simões, CETP/IPSL-CNRS, France, and a member of the PWA team. Sketch of radio wave detected during Huygens' descent If Simões is right, successful modelling of how ELF waves resonate on Titan could lend support to the ocean’s existence and tell scientists about the depth at which it sits. Understanding the resonance however, is difficult. Above about 100 kilometres altitude on Earth, the ionosphere provides the upper reflecting layer of the resonating cavity. At Titan, PWA revealed that things are more complicated. Apart from the ionosphere, at a much higher altitude of about 1200 kilometres, Huygens found a layer of ionized particles consisting of electrons, at 63 kilometres. “This does not match any previous prediction for Titan,” says Simões. To some extent, it splits Titan’s atmosphere into two resonating chambers. With so much at stake, the PWA team are checking to make sure the detection is real and not an artefact generated by the spacecraft. They have already ruled out electrical interference from the instrument itself. Two small arms, one on either side of Huygens, create an antenna and the team’s next goal is to investigate whether the arms could have oscillated during the descent. Simões and colleagues are building a special chamber to hold a replica of the instrument at the low temperature of Titan’s atmosphere, between 100-200 degrees Kelvin (about -173 to -73 °C), in order to check whether the antenna resonates at 36 hertz. If it does, it probably means that the signal is an artefact. If it does not, confidence in the signal’s reality will increase and the investigation of the atmosphere and subsurface can begin. Graph of electron density in Titan's atmosphere But perhaps the biggest mystery is what generated the ELF wave in the first place. On Earth, they are initiated by lightning strikes that make electrons in the atmosphere oscillate, releasing the ELF waves. The PWA was designed to search for ELF waves on Titan while a microphone on Huygens kept an ear out for thunder – a sure sign of lightning. Cassini has also been watching for lightning using its cameras. However, Huygens suggests that there is no lightning, or very little. “If there is lightning on Titan, it is significantly less than the amount of lightning that Earth experiences,” says Simões. So what generated Titan’s ELF? No one is quite sure yet. “It might be generated by an interaction with Saturn’s magnetosphere or related to Titan’s intrinsic fields,” suggests Simões. “Titan is proving to be an intriguing environment.” One thing is certain: there is plenty to investigate. “The measurement of atmospheric electricity is something really new and exciting,” says Jean-Pierre Lebreton, ESA Huygens Project Scientist. “We could send similar instruments to study atmospheric electricity on other celestial bodies, in particular Venus, Mars, and the giant planets,” adds Simões. The PWA team expect to release more definitive results when their investigation is complete. Notes for editors This article is based on two papers that will appear in a special issue of the Planetary and Space Science magazine dedicated to Huygens results: ‘Electron conductivity and density profiles derived from the Mutual Impendence Probe measurements performed during the descent of Huygens through the atmosphere of Titan’, by M. Hamelin et al., and ‘A new numerical model for the simulation of ELF wave propagation and the computation of eigenmodes in the atmosphere of Titan: did Huygens observe any Schumann Resonance?’, by F. Simões et al.

[Mugge]

Cool. Now how do we get a submarine up there?

[curiousuburb]

Call the Moravecs... oh wait... wrong gas giant.

(Mahnmut in Illium is a Europan Submariner.)

[Mugge]

Originally Posted by curiousuburb Call the Moravecs... oh wait... wrong gas giant. (Mahnmut in Illium is a Europan Submariner.)

You confuse me with sci-fi, as if this space magnetism shit wasn't complicated enough to begin with.

[Moogs]

This stuff is a trip... how amazing that we're doing this kind of science. Gives me hope for mankind, if we can keep from asploding each other, dying from plagues, etc.

[curiousuburb]

Iapetus Bulge explained

Originally Posted by Space.com Walnut-Shaped Moon's Mystery Solved By Dave Mosher Staff Writer posted: 23 July 2007 06:46 am ET There's a strange moon whizzing around Saturn that's shaped, oddly, like a walnut. Now astronomers find that Iapetus got its nutty shape from a super-fast spin that was frozen into place early in the solar system's formation. When the Cassini spacecraft snapped close-ups of Saturn's moons in 2005, it revealed a bulging waistline of rock along the equator of the now slowly spinning Iapetus. Astronomers think this characteristic shape persists because Iapetus was cryogenically frozen in time about 3 billion years ago, during the moon's "teen" years. "Iapetus spun fast, froze young and left behind a body with lasting curves," said Julie Castillo, a Cassini scientist at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif. Unlike any other moon in the solar system, Iapetus (eye-APP-eh-tuss) has retained its immature figure. Running exactly along its midsection, a chain of mountains 808 miles (1,300 kilometers) long and 12 miles (19 kilometers) high adds to the moon's walnut-like appearance. "You would expect a very fast-spinning moon to have this bulge but not a slow-spinning moon, because the bulge would have been much flatter," said Dennis Matson, another Cassini project scientist at JPL. However, Mason said, "we've modeled how Iapetus formed its big, spin-generated bulge and why its rotation slowed down to its present, nearly 80-day period." Iapetus originally spun once every five to 16 hours, which was fast enough to buckle its surface at the equator, according to the new model detailed in an upcoming online edition of the journal Icarus. Scientists think radioactive elements heated the moon's interior to permit the crust to stretch and buckle, yet quickly froze the moon into shape as fuel ran out. "Iapetus' development literally stopped in its tracks," Castillo said of the 4.564 billion-year-old hunk of rock. In order to slow the young moon down its present once-per-80-days rotational speed, Castillo explained, "its interior had to be much warmer, close to the melting point for water ice." The finding should help astronomers better understand how the planets and their moon systems formed in the early solar system. "This is the first direct evidence of the early spin history for a satellite in the outer solar system," Matson said. "It ... broadens our knowledge of the early history of outer planet satellites."

Originally Posted by Cassini Saturn's Old Moon Iapetus Retains its Youthful Figure July 17, 2007 (Source: Jet Propulsion Laboratory) Press Release Saturn's distinctive moon Iapetus (eye-APP-eh-tuss) is cryogenically frozen in the equivalent of its teenage years. The moon has retained the youthful figure and bulging waistline it sported more than three billion years ago, scientists report. Unlike any other moon in the solar system, Iapetus is the same shape today as it was when it was just a few hundred million years old. "Iapetus spun fast, froze young, and left behind a body with lasting curves," said Julie Castillo, Cassini scientist at NASA's Jet Propulsion Laboratory, Pasadena, Calif. Unlike any other moon in the solar system, Iapetus is the same shape today as it was when it was just a few hundred million years old; a well-preserved relic from the time when the solar system was young. These results appear in the online version of the journal Icarus. Cassini flew by Iapetus in early 2005 and discovered the moon had a walnut shape, bulging at its midsection. On top of that it has a chain of mountains located exactly along its equator. Scientists now think the moon's bulging midriff and slow spin rate point to heating from long-extinct radioactive elements present when the solar system was born. "We've modeled how Iapetus formed its big, spin-generated bulge and why its rotation slowed down to its present nearly 80-day period. As an unexpected bonus, Iapetus also told us how old it was," said Dennis Matson, Cassini project scientist at JPL. "You would expect a very fast-spinning moon to have this bulge, but not a slow-spinning moon, because the bulge would have been much flatter." Scientists calculate Iapetus originally rotated much faster -- at least five hours, but less than 16 hours per revolution. The fast spin gave the moon an oblate shape that increased the surface area (in the same way the surface area of a round balloon stretches when the balloon is pressed into an oblate shape). By the time the rotation slowed down to a period of 16 hours, the outer shell of the moon had frozen. Furthermore, the surface area of the cold moon was now smaller. The excess surface material was too rigid to go back smoothly into the moon. Instead, it piled up in a chain of mountains at the equator. "Iapetus' development literally stopped in its tracks," said Castillo. "In order for tidal forces to slow Iapetus to its current spin rate, its interior had to be much warmer, close to the melting point for water ice." The challenge in developing a model of how Iapetus came to be "frozen in time" has been in deducing how it ever became warm enough to form a bulge in the first place, and figuring out what caused the heat source to turn off, leaving Iapetus to freeze. The heat source had to have a limited life span, to allow the moon's crust to rapidly become cold and retain its immature shape. After looking at several models, scientists concluded that the heat came from its rocks, which contain short-lived radioactive isotopes aluminum-26 and iron-60 (which decay very rapidly on a geologic timescale). Since these elements decay at a known rate, this allowed scientists to "carbon date" Iapetus by using aluminum-26 instead of carbon. Scientists calculate the age of Iapetus to be roughly 4.564 billion years old. Evidence for these same isotopes (aluminum-26 and iron-60) has been found in meteorites formed in the inner solar system. Therefore, there is a possibility of comparing the early chronology of the outer solar system with other objects in the inner solar system, such as Earth, Earth's moon and asteroids. "This is the first direct evidence of the early spin history for a satellite in the outer solar system. It teaches us more about how the speed of a body's rotation influenced its evolution, and broadens our knowledge of the early history of outer planet satellites," said Matson. Cassini's next close encounter with Iapetus will occur on Sept. 10, 2007, at 1,000 kilometers (620 miles) from the surface. The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA's Science Mission Directorate, Washington, D.C. More information on the Cassini mission is available at: http://saturn.jpl.nasa.gov and http://www.nasa.gov/cassini .

Saturnian Moon count reaches 60

Originally Posted by Cassini Saturn Turns 60 Jul. 19, 2007 (Source: JPL) Scientists have recently discovered that the planet Saturn is turning 60 -- not years, but moons. Initial calculations show the moon to have a width of approximately 2 kilometers (1.2 miles), with an orbit that lies between those of the moons Methone and Pallene. View QT Movie The 60th moon of Saturn reveals itself in a sequence of images. The discovery suggests that the new moon, along with its neighbors Methone and Pallene (discovered by the Cassini imaging team in 2004), may form part of a larger group of moons in this region. The movie spans six hours. Initial calculations show the moon to have a width of approximately 2 kilometers (1.2 miles), with an orbit that lies between those of the moons Methone and Pallene. The moon's orbit is in resonance with another moon, Mimas, also seen in this sequence as a very bright, moving object. The new moon's location is indicated by a red box. The (narrow) ring visible in the images is the G ring, and the G ring arc passes through the field of view during the course of the movie. Calypso, a Trojan moon of Tethys, is also visible in the sequence. Trojan moons are found near gravitationally stable points ahead or behind a larger moon. This view looks toward the non-illuminated side of the rings from about 3 degrees above the ringplane. The series of images was taken in visible light with the Cassini spacecraft wide-angle camera on May 30, 2007, at a distance of approximately 1.76 million kilometers (1.09 million miles) from Saturn. Image scale is about 105 kilometers (65 miles) per pixel. The ghostly shape that stretches across the scene results from scattered light within the camera optics. "We detected the 60th moon orbiting Saturn using the Cassini spacecraft's powerful wide-angle camera," said Carl Murray, a Cassini imaging team scientist from Queen Mary, University of London. "I was looking at images of the region near the Saturnian moons Methone and Pallene and something caught my eye." The newly discovered moon first appeared as a very faint dot in a series of images Cassini took of the Saturnian ring system on May 30 of this year. After the initial detection, Murray and fellow Cassini imaging scientists played interplanetary detective, searching for clues of the new moon in the voluminous library of Cassini images to date. The Cassini imaging team's legwork paid off. They were able to locate numerous additional detections, spanning from June 2004 to June 2007. "With these new data sets we were able to establish a good orbit for the new moon," said Murray. "Knowing where the moons are at all times is important to the Cassini mission for several reasons." One of the most important reasons for Cassini to chronicle these previously unknown space rocks is so the spacecraft itself does not run into them. Another reason is each discovery helps provide a better understanding about how Saturn's ring system and all its billions upon billions of parts work and interact together. Finally, a discovery of a moon is important because with this new knowledge, the Cassini mission planners and science team can plan to perform science experiments during future observations if and when the opportunity presents itself. What of this new, 60th discovered moon of Saturn? Cassini scientists believe "Frank" (the working name for the moon until another, perhaps, more appropriate one is found) is about 2 kilometers (1.2 miles) wide and, like so many of its neighbors, is made mostly of ice and rock. The moon's location in the Saturnian sky is between the orbits of Methone and Pallene. It is the fifth moon discovered by the Cassini imaging team. "When the Cassini mission launched back in 1997, we knew of only 18 moons orbiting Saturn," said Murray. "Now, between Earth-based telescopes and Cassini we have more than tripled that number -- and each and every new discovery adds another piece to the puzzle and becomes another new world to explore." Murray and his colleagues may get the chance to explore Saturn's 60th moon. The Cassini spacecraft's trajectory will put it within 11,700 kilometers (7,300 miles) in December of 2009.

Cheers to the new moon named... Frank.

[curiousuburb]

Cassini's only close (1600 km) flyby of the curious moon Iapetus (discovered by the original Giovanni Cassini in 1671) is done.

Despite a cosmic ray hit that put the spacecraft into safe mode and delayed downlink of the data, there are some impressive new images of the 'yin-yang moon' with the walnut ridge.

Originally Posted by Cassini Scientists on the Cassini mission to Saturn are poring through hundreds of images returned from the Sept. 10 flyby of Saturn's two-toned moon Iapetus. Pictures returned late Tuesday and early Wednesday show the moon's yin and yang -- a white hemisphere resembling snow, and the other as black as tar. Cassini's Closest Visit of Iapetus On Sept. 10, the Cassini spacecraft performs its closest flyby during the entire mission of the odd moon Iapetus, passing by about 1,640 kilometers (1,000 miles). Iapetus is a world of sharp contrasts. The leading hemisphere is as dark as a freshly-tarred street, and the white, trailing hemisphere resembles freshly-fallen snow. Scientists want to know more about the composition of the dark material that coats Iapetus. They also want to learn more about Iapetus' distinctive walnut shape and the chain of mountains along its equator.

Originally Posted by Cassini Saturn's Moon Iapetus is the Yin-and-Yang of the Solar System September 12, 2007 (Source: NASA/JPL/Space Science Institute) This close-up view shows mountainous terrain that reaches about 10 kilometers (6 miles) high along the unique equatorial ridge of Iapetus. PASADENA, Calif. -- Scientists on the Cassini mission to Saturn are poring through hundreds of images returned from the Sept. 10 flyby of Saturn's two-toned moon Iapetus. Pictures returned late Tuesday and early Wednesday show the moon's yin and yang -- a white hemisphere resembling snow, and the other as black as tar. Images show a surface that is heavily cratered, along with the mountain ridge that runs along the moon's equator. Many of the close-up observations focused on studying the strange 20-kilometer high (12 mile) mountain ridge that gives the moon a walnut-shaped appearance. "The images are really stunning," said Tilmann Denk, Cassini imaging scientist at the Free University in Berlin, Germany, who was responsible for the imaging observation planning. "Every new picture contained its own charm. I was most pleased about the images showing huge mountains rising over the horizon. I knew about this scenic viewing opportunity for more than seven years, and now the real images suddenly materialized." This flyby was nearly 100 times closer to Iapetus than Cassini's 2004 flyby, bringing the spacecraft to about 1,640 kilometers (1,000 miles) from the surface. The moon's irregular walnut shape, the mountain ridge that lies almost directly on the equator and Iapetus' brightness contrast are among the key mysteries scientists are trying to solve. This image shows terrain in the transition region between the moon's dark leading hemisphere and its bright trailing hemisphere. "There's never a dull moment on this mission," said Bob Mitchell, Cassini program manager, NASA's Jet Propulsion Laboratory, Pasadena, Calif. "We are very excited about the stunning images being returned. There's plenty here to keep many scientists busy for many years." "Our flight over the surface of Iapetus was like a non-stop free fall, down the rabbit hole, directly into Wonderland! Very few places in our solar system are more bizarre than the patchwork of pitch dark and snowy bright we've seen on this moon," said Carolyn Porco, Cassini imaging team leader at the Space Science Institute, Boulder, Colo. The return of images and other data was delayed early Tuesday due to a galactic cosmic ray hit which put the spacecraft into a precautionary state called safe mode. This occurred after the spacecraft had placed all of the flyby data on its data recorders and during the first few minutes after it began sending the data home. The data flow resumed later that day and concluded on Wednesday. The spacecraft is operating normally and its instruments are expected to return to normal operations in a few days. "Iapetus provides us a window back in time, to the formation of the planets over four billion years ago. Since then its icy crust has been cold and stiff, preserving this ancient surface for our study," said Torrence Johnson, Cassini imaging team member at JPL. Cassini's multiple observations of Iapetus will help to characterize the chemical composition of the surface; look for evidence of a faint atmosphere or erupting gas plumes; and map the nighttime temperature of the surface. These and other results will be analyzed in the weeks to come. The 'Voyager' Mountains Coated Craters Inky Stains on a Frozen Moon The Himalayas of Iapetus Eyes on Iapetus! Exposing Iapetus' Dark Side More Iapetus flyby images are available at: http://saturn.jpl.nasa.gov and http://www.nasa.gov/cassini and http://ciclops.org.

And Arthur C Clarke webcast a message (click pic above for link) for the JPL/Cassini folks to mark the flyby of the moon he actually chose for the big Monolith in 2001. The clip explains why Kubrick switched to Jupiter in the film when the book used Saturn.

Space science and film trivia connected by a brilliantly prescient author... trifecta!

[Moogs]

Sorta related

http://news.bbc.co.uk/2/hi/science/nature/7082257.stm

Seems the Cancri system is uber-planetized.

[Moogs]

More Astro-news.... we're always talking about planets getting pummeled by asteroids and such. How about every planetary system on the edge of an entire galaxy getting wiped out by a SMBH "jet"?

http://news.bbc.co.uk/2/hi/science/nature/7148671.stm

[curiousuburb]

Meanwhile, the boffins are bickering over the composition of the Enceladus jets.

Grains of salt should be taken when reading this story... but might not be detected.

http://news.bbc.co.uk/1/hi/sci/tech/7145530.stm

Sodium issue clouds Enceladus By Molly Bentley Science reporter, San Francisco Dec 16, 2007 Next year, Cassini will attempt to fly through the jets An ocean is not the source of the jets emanating from Saturn's moon Enceladus, a new study concludes. The research questions the moon's promise as a target in the search for life beyond Earth and has stirred controversy among scientists who dispute its conclusions. A chemical analysis of Enceladus, led by University of Colorado planetary scientist Nick Schneider, failed to detect sodium, an element scientists say should be in a body of water that has had billions of years of contact with rock. "If you have a long-lived ocean, it's going to have salt in it," said Dr Schneider, at the American Geophysical Union (AGU) meeting in San Francisco this week, "but that ocean, if it exists on Enceladus, isn't leaking out into space." Spectral analysis with the Keck Telescope found no sodium in the plumes or in the vapour that's in orbit around the moon. The source of the plumes is "very, very pure water," Dr Schneider concluded, and proposed clean ice, melt water or clathrates - a crystal of water, carbon dioxide and ammonia - as alternative sources. Heated debate The fountains on Enceladus tantalise scientists by suggesting an ocean beneath the moon's icy crust. An ancient sea is the best bet for where life might evolve off Earth, scientists say. At stake is whether Saturn's moon could support alien life and is a worthy target for a US space agency (Nasa) exploratory mission to detect it. Such a mission to Enceladus is one of four currently under review for further development. If you took salt from a salt-shaker and threw it into the air, the telescope wouldn't see any sodium, even though half the salt is sodium Torrence Johnson, Cassini Imaging Team Dr Schneider didn't rule out the possibility of an ocean on Enceladus, only that it is the source of the spraying water. Critics of the study accept his observations, but disagree with his conclusion; and it has led to some robust exchanges here at the AGU meeting this past week. "There is tremendous dispute about his interpretation of the results," said Carolyn Porco, the Imaging Team leader on the Cassini spacecraft. He may not have detected sodium, she said, but it did not follow that the plumes were not connected to an ocean. The absence of detectable sodium might mean only that; it's not detectible, said Dr Porco. It could be in a solid form that eludes detection by this method, she said. Salty secrets Dr Schneider used the Keck Telescope to look for a glow from sodium atoms, the same colour found in sodium streetlights. He failed to detect it in the plume or in the ring of particles that encircle Saturn at Enceladus' orbit. ENCELADUS ORBITER CONCEPT To look at biological potential, composition and structure Instruments to image and sample surface and jets Lander to provide unique close-up view of surface processes Probable cost about $3bn; 2018 launch on biggest Delta rocket Yet sodium is quite abundant in the Solar System, said Torrence Johnson, Cassini Imaging Team member at Nasa's Jet Propulsion Laboratory. "It's a very surprising result not to find sodium at all," he explained. "So the question is: can you hide the sodium?" One way to hide sodium is to put it in a salt crystal that becomes the nucleus of a water particle. If a sodium atom were tied up in a solid form, the Keck Telescope would not detect it. It only detects liberated sodium atoms, he said. "If you took salt from a salt-shaker and threw it into the air, the telescope wouldn't see any sodium, even though half the salt is sodium," added Dr Johnson. Dr Schneider said that the molecules would release sodium as they made their way into the particles that encircle Saturn. Near fly-by Scientists have detected sodium around Jupiter's moons Io and Europa. Volcanoes produce Io's sodium and their heat liberates it. Scientists believe Jupiter's energetic radiation belt kicks the sodium out of minerals that entrap it on Europa. But Saturn is cooler in temperature and its radiation levels may also be too weak to free sodium. At any rate, said Dr Johnson, the sodium-free test results do not rule out the existence of an ocean on the moon or an ocean as the source of the plumes. The Cassini spacecraft is scheduled to fly close to the jets in March of next year. It will analyse the water further, but is not able to test for sodium. Nonetheless, the discovery of water spewing from cracks - dubbed "tiger stripes" -on Enceladus in 2006, has promoted the moon into an elite club of outer Solar System bodies that are considered high priority for future Nasa missions. Design competition The possibility that the plumes tap directly into a lunar ocean is the impetus behind a flagship mission that would explore Enceladus further. A spacecraft that flew through the spray might be designed to sample the water directly and run tests to detect the presence of alien microbes. The tiger stripes, or sulci, are now the focus of intense study More details The mission is much more difficult - and expensive - if the data is not obtainable at altitude and a lander has to be put on the icy surface to reach it. The Enceladus flagship mission is one of four - along with those to Europa, Titan and Jupiter - competing for funding and currently under review by Nasa. Dr Johnson says Dr Schneider's study might influence how inclined people are to send a spacecraft to Enceladus and fly through the plumes. "If Nick is right," he said, "all they'd see is pure water." Nasa is scheduled to select which flagship missions will advance at the end of December. The concept that eventually emerges in the process will launch no earlier than 2015 and is likely to include sizeable input from the Europeans.

[curiousuburb]

Cassini at Saturn Interactive Explorer (CASSIE)


Real data... handy web 3D browser plugin.

Welcome to NASA's first 3-d interactive mission experience using a web browser. Using "Cassini at Saturn Interactive Explorer"(CASSIE) you can observe or ride along with the Cassini spacecraft as it explores Saturn and its moons using real mission data. The first time you click on the button below it will automatically download and install the needed software (a free plug-in to your web-browser) and the real Cassini mission data. The download is about 15 megabytes so it should only take a minute or two. (If you use a Mac you may need to install the software after it downloads and then restart your web-browser.) Once the plug-in is installed and the mission data is loaded you're ready for your trip to the Saturn System. When CASSIE appears in your web browser, you'll see three clickable windows. The Cassini at Saturn Interactive Explorer, or CASSIE, visualizes the real Cassini mission data in these three windows. (WINDOW 1) The "Where is Cassini Now?" expedition shows exactly where the Cassini spacecraft is, and what it is doing each moment over a 24-hour period in real time. Viewers can see the spacecraft move along its course and maneuver according to instructions from mission scientists and navigators. (WINDOW 2) The "Mission Overview" expedition, shows the spacecraft as it orbits the Saturn system over the last 3.5 years and fast-forward into the future to see where it is going. Users can switch between two camera angles to see Cassini fly by Saturn and its moons. (WINDOW 3) The "Saturn's Moons" expedition gives an in-depth peek at seven of Saturn's moons, providing useful facts and interactive surface views of each moon.

Teh Coolness!

[curiousuburb]

Enceladus close pass in 1 hour.



50km above the surface and through the geysers at under 200km altitude to sample the contents.

Sadly, the imaging array will be turned out to space during the geyser dive so that the particle analyzers can get their best sniff.

Click for video
On March 12, NASA's Cassini spacecraft will make its closest flyby yet to Saturn's moon Enceladus. Cassini's goal: To scoop up samples of water-ice particles and gas spewing from Old-Faithful-like geysers.

Cassini Spacecraft to Dive Into Water Plume of Saturn Moon March 10, 2008 (Source: NASA/JPL) NASA's Cassini spacecraft will make an unprecedented "in your face" flyby of Saturn's moon Enceladus on Wed., March 12. The spacecraft, orchestrating its closest approach to date, will skirt along the edges of huge Old-Faithful-like geysers erupting from giant fractures on the south pole of Enceladus. Cassini will sample scientifically valuable water-ice, dust and gas in the plume. The source of the geysers is of great interest to scientists who think liquid water, perhaps even an ocean, may exist in the area. While flying through the edge of the plumes, Cassini will be approximately 200 kilometers (120 miles) from the surface. At closest approach to Enceladus, Cassini will be only 50 kilometers (30 miles) from the moon. This graphic shows the trajectory for the Cassini spacecraft during its close brush with the icy outpost of Enceladus on March 12, 2008. At closet approach Cassini will be 50 kilometers (30 miles) from the surface, while flying through the plume Cassini's altitude will be 200 kilometers (120) miles from the moon. "This daring flyby requires exquisite technical finesse, but it has the potential to revolutionize our knowledge of the geysers of Enceladus. The Cassini mission team is eager to see the scientific results, and so am I," said Alan Stern, associate administrator of NASA's Science Mission Directorate, Washington. Scientists and mission personnel studying the anatomy of the plumes have found that flying at these close distances poses little threat to Cassini because, despite the high speed of Cassini, the plume particles are small. The spacecraft routinely crosses regions made up of dust-size particles in its orbit around Saturn. Cassini's cameras will take a back seat on this flyby as the main focus turns to the spacecraft's particle analyzers that will study the composition of the plumes. The cameras will image Enceladus on the way in and out, between the observations of the particle analyzers. Images will reveal northern regions of the moon previously not captured by Cassini. The analyzers will "sniff and taste" the plume. Information on the density, size, composition and speed of the gas and the particles will be collected. This map of the surface of Saturn's moon Enceladus, generated from images taken by NASA's Cassini and Voyager spacecraft, illustrates the imaging coverage planned for Cassini's very close flyby of the geologically active moon on March 12, 2008. "There are two types of particles coming from Enceladus, one pure water-ice, the other water-ice mixed with other stuff," said Sascha Kempf, deputy principal investigator for Cassini's Cosmic Dust Analyzer at the Max Planck Institute for Nuclear Physics in Heidelberg, Germany. "We think the clean water-ice particles are being bounced off the surface and the dirty water-ice particles are coming from inside the moon. This flyby will show us whether this concept is right or wrong." In 2005, Cassini's multiple instruments discovered that this icy outpost is gushing water vapor geysers out to a distance of three times the radius of Enceladus. The moon is only 500 kilometers (310 miles) in diameter, but despite its petite size, it's one of the most scientifically compelling bodies in our solar system. The icy water particles are roughly one ten-thousandth of an inch, or about the width of a human hair. The particles and gas escape the surface at jet speed at approximately 400 meters per second (800 miles per hour). The eruptions appear to be continuous, refreshing the surface and generating an enormous halo of fine ice dust around Enceladus, which supplies material to one of Saturn's rings, the E-ring. Several gases, including water vapor, carbon dioxide, methane, perhaps a little ammonia and either carbon monoxide or nitrogen gas make up the gaseous envelope of the plume. "We want to know if there is a difference in composition of gases coming from the plume versus the material surrounding the moon. This may help answer the question of how the plume formed," said Hunter Waite, principal investigator for Cassini's Ion and Neutral Mass Spectrometer at the Southwest Research Institute, San Antonio. This is the first of four Cassini flybys of Enceladus this year. In June, Cassini completes its prime mission, a four-year tour of Saturn. Cassini's next flyby of Enceladus is planned for August, well into Cassini's proposed extended mission. Cassini will perform seven Enceladus flybys in its extended mission. If this encounter proves safe, future passes may bring the spacecraft even closer than this one. How close Cassini will be allowed to approach will be determined based on data from this flyby. The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL manages the Cassini-Huygens mission for NASA's Science Mission Directorate. The Cassini orbiter was designed, developed and assembled at JPL. For images, videos and a mission blog on the flyby, visit: http://www.nasa.gov/cassini . More information on the Cassini mission is also available at http://saturn.jpl.nasa.gov .

See also the groovy interactive Enceladus virtual tour.
(With new close up images of the Northern hemisphere due after this flyby).


Oh... and apparently, Rhea has Rings. First moon in the solar system to have them.

[curiousuburb]

Cassini picks up a mushroom... Extended mission!¡!

And the CASSIE 3D explorer is updated to v2.0

Originally Posted by Cassini Cassini's Adventure Ends, and Begins Anew The Cassini Mission was an audacious idea from the start. Get the world's best space scientists and engineers to build the best and hardiest instruments that they can to study Saturn. Put everything on a spacecraft and launch it to the outer solar system. Loop twice around Venus, once around Earth, then pass Jupiter. When you get to Saturn, veer right and slam on the brakes. Pass through the rings. Look out for those ice particles! Start orbiting Saturn. Hang out a lot at Titan - it's smoggy but that's where the action is. Drop off the Huygens Probe there and tell us everything it has to say about what it finds. Check out Enceladus; something strange is going on there. Go by Iapetus. It is definitely weird. There are a bunch of little moons hiding in and around the rings, making waves and kicking up dust. Find them. And fly way up above Saturn a few times. We've never seen it from that view. Be open to the unexpected. Stay for at least four years. Report back on everything that you see, feel, smell and hear. Take lots of pictures! Astonishingly, Cassini's historic prime mission has successfully concluded. It may have looked easy, but the mission's success is owed to the careful and hard work of the dedicated international team that built and operates the spacecraft. Now, Cassini embarks on the new Equinox mission with a fresh set of scientific objectives. Since arriving at the ringed planet four years ago, Cassini has revealed wonder after wonder. The growing body of knowledge about Saturn, its rings, moons and magnetic environment is allowing scientists to link together clues to solve mysteries. For every puzzle solved, Cassini seems to raise 10 more new questions - a happy predicament for scientists. Cassini-Huygens Analysis and Results of the Mission (CHARM) View June 24, 2008 Presentation (PDF, 13MB) Some highlights of the prime, four-year Cassini mission: Geysers shoot water vapor and ice from warm fissures on Enceladus. The E-ring of Saturn is made of material from Enceladus' plumes. Material from Enceladus' plumes adds mass to Saturn's magnetosphere and slows the rotation of Saturn's magnetic field. Comet-like organic chemicals exist in Enceladus' plumes. Titan appears to be land of lakes, with hundreds of lake features, probably filled with hydrocarbons. Titan has a hydrological cycle like Earth's but substitutes methane for water in processes that include methane rain, clouds and apparently, lakes. Braided channels are carved in Titan's surface -- evidence of heavy flooding. Small moons, including Hyperion, are dazzlingly varied and strange. Sahara-like sand dunes exist on Titan, and the sand is probably made up of hydrocarbons that fall from the sky. An internal ocean likely exists on Titan. It causes Titan's crust to slip about "like cheese on pizza sauce." Evidence exists for a tenuous ring system around the moon Rhea. An odd mountain ridge runs around Iapetus' equator. Detailed studies of Iapetus, frozen in time, shed new light on the early formation of other bodies in the solar system. The Huygens Probe returned the first close-up views of Titan's haze-covered terrain. Landing onto damp, icy gravel or sand at edge of a dried-up methane lake, the Huygens Probe provided new insight into the makeup of Titan. Titan is losing its atmosphere due to bombardment by Saturn's magnetosphere. Extremely heavy organic compounds, up to 10,000 times heavier than hydrogen - were found high in Titan's atmosphere. These become aerosols and eventually rain down onto Titan's cold surface - they may be the "tholins" predicted by Carl Sagan that comprise a prebiotic chemical soup. Auroras at Saturn's north and south poles are unlike those found on Earth and Jupiter. Hot hurricane-like storms churn at both of Saturn's poles. The temperature structure of Saturn's and Titan's atmospheres were completely mapped, revealing their circulation and dynamics. The rings have their own atmosphere. Evidence was found that the rings may be a permanent rather than transitory feature of Saturn Enceladus geysers Titan, Land of Lakes. Spongy Hyperion. Titan's landscape, from Huygens Long-lived storm at Saturn's south pole.

Extended mission should include a ring eclipse in 2009 and fresh approach to a few moons for follow up.

[curiousuburb]

Cassini has captured Prometheus colliding with the F ring, which creates a "streamer;" material being pulled from the ring by the moon's gravity, leaving behind a dark channel.

Originally Posted by Cassini Streamer Channel The Cassini spacecraft focuses on a streamer-channel feature in Saturn's F ring. These features are created by the moon Prometheus as it closely approaches the ring once per orbit (see Soft Collision). This view looks toward the unilluminated side of the rings from about 36 degrees above the ringplane.The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Sept. 30, 2008. The view was acquired at a distance of approximately 970,000 kilometers (602,000 miles) from Saturn and at a Sun-ring-spacecraft, or phase, angle of 45 degrees. Image scale is 5 kilometers (3 miles) per pixel.

Even better, you can watch it happen...

Originally Posted by Cassini Soft Collision MPG of the event. QT version The moon Prometheus slowly collides with the diffuse inner edge of Saturn's F ring in this movie sequence of Cassini images. The oblong moon pulls a streamer of material from the ring and leaves behind a dark channel. Once 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. At this point, Prometheus' gravity is just strong enough to draw a "streamer" of material out of the core region of the F ring. Initially the dust-sized material drawn away from the ring appears to form a streamer pointing ahead of Prometheus in its orbit. (All orbital motion is towards the right in the movie.) Over time, the streamer falls increasingly farther behind Prometheus because material in the F ring is orbiting slower than the moon. The streamer gets longer and a darker "channel" starts to be seen (to the left of the streamer in the movie). The creation of such streamers and channels occurs in a cycle that repeats each Prometheus orbit: when Prometheus again reaches apoapse, it draws another streamer of material from the F ring. But since Prometheus orbits faster than the material in the ring, this new streamer is pulled from a different location in the ring about 3.2 degrees (in longitude) ahead of the previous one. In this way, a whole series of streamer-channels is created along the F ring. In some observations, 10 to 15 streamer-channels can easily be seen in the F ring at one time (see Shaping the Drapes). Eventually, a streamer-channel disappears as shearing forces (i.e., Keplerian shear) act to disperse the constituent dust particles. The movie shows just under half of a complete streamer-channel cycle. The dark frames in the movie represent the period during which Prometheus and the F ring pass through Saturn's shadow. The images in the movie were acquired by the Cassini spacecraft narrow-angle camera on Nov. 23 and 24, 2006. The movie sequence consists of 72 clear spectral filter images taken every 10.5 minutes over a period of about 12.5 hours. The original images were cropped to show only the region around Prometheus and the nearby portion of the F ring. The movie covers the region between 138,000 and 142,000 kilometers (86,000 and 88,000 miles) radially from Saturn and 1 degree in longitude from Prometheus on each side. Each frame was reprojected such that the vertical axis represents distance from Saturn and the horizontal axis represents longitude around Saturn. Image scale is 10 kilometers (6 miles) per pixel in the vertical direction; the images cover 0.005 degrees of longitude in the horizontal direction. Because of the reprojection, the F ring appears straight, rather than slightly curved, as it otherwise would. Since the F ring has an elliptical shape, its radial distance from Saturn varies by about 1,000 kilometers (620 miles) around the ring. This accounts for the apparent vertical movement of the ring over the course of the movie. Only a very small part of the ring appears in each of the reprojected frames, so the difference in the ring's radial distance from left to right across any single frame is small enough as to be effectively unnoticeable.

See also this shot of Prometheus and Pandora for another view of the channels



So the shepherds do their thing here... and apparently planets do it around other stars... Hubble just announced photos of an ExoPlanet around Fomalhaut (25ly away)...



Wo0t!

[Moogs]

Looks like a mandlebot image. Very cool!

[curiousuburb]

So in addition to updating the main Cassini mission site in honour of the extended 'Equinox' mission...

Two new true-colour photo releases that are candidates for awesome desktop pictures (I've tried to use thumbs to limit scroll, but extra res is available).

Detailed labels of the rings and gaps

A Full Sweep of Saturn's Rings (with labels) December 30, 2008 Full-Res: PIA11142 + Unlabeled Version Details of Saturn's icy rings are visible in this sweeping view from Cassini of the planet's glorious ring system. This natural color mosaic, taken from 10 degrees below the illuminated side of the rings, shows, from left to right, radially outward from Saturn, the C ring (with its Colombo and Maxwell gaps); the B ring and the Cassini division beyond, with the intervening Huygens gap; the A ring (with its Encke and Keeler gaps); and, on the far right, the narrow F ring. The total span covers approximately 65,700 kilometers (40,800 miles). Although it is too faint to be seen here, the D ring is located just to the left of the C ring. It is interesting to compare this view with Expanse of Ice, which shows the unilluminated side of the rings. The difference in brightness of the B ring relative to the other rings is striking. When illuminated directly by the sun, the B ring appears brighter than the adjacent A and C rings; however, when viewing the unlit side of the B ring, the A and C rings appear brighter. This phenomenon occurs because the density of the B ring is greater than that of the A or C rings. The mosaic was constructed from 45 narrow-angle-camera images -- 15 separate sets of red, green and blue images -- taken over the course of about four hours, as Cassini scanned across the rings. The images in this view were obtained by NASA's Cassini spacecraft on Nov. 26, 2008, at a distance of approximately 1.1 million kilometers (700,000 miles) from Saturn and at a sun-Saturn-spacecraft, or phase, angle of 28 degrees. Image scale in the radial (horizontal) direction is about 6 kilometers (3.5 miles) per pixel.

And a 'family portrait' with 6 moons, including Titan

Saturn ... Four Years On December 30, 2008 Full-Res: PIA11141 <-- 4800x2653 version Wo0t! As Saturn advances in its orbit toward equinox and the sun gradually moves northward on the planet, the motion of Saturn's ring shadows and the changing colors of its atmosphere continue to transform the face of Saturn as seen by Cassini. This captivating natural color view was created from images collected shortly after Cassini began its extended Equinox Mission in July 2008. It can be contrasted with earlier images from the spacecraft's four-year prime mission that show the shadow of Saturn's rings first draped high over the planet's northern hemisphere, then shifting southward as northern summer changed to spring (see Serenity of Saturn and Sliding Shadows ). During this time, the colors of the northern hemisphere have evolved from azure blue to a multitude of muted-colored bands. This mosaic combines 30 images -- 10 each of red, green and blue light -- taken over the course of approximately two hours as Cassini panned its wide-angle camera across the entire planet and ring system on July 23, 2008, from a southerly elevation of 6 degrees. Six moons complete this constructed panorama: Titan (5,150 kilometers, or 3,200 miles, across), Janus (179 kilometers, or 111 miles, across), Mimas (396 kilometers, or 246 miles, across), Pandora (81 kilometers, or 50 miles, across), Epimetheus (113 kilometers, or 70 miles, across) and Enceladus (504 kilometers, or 313 miles, across). NASA's Cassini spacecraft captured these images at a distance of approximately 1.1 million kilometers (690,000 miles) from Saturn and at a sun-Saturn-spacecraft, or phase, angle of 20 degrees. Image scale is 70 kilometers (43.6 miles) per pixel.

Earthbound observers will miss the Rings for a while, as orbital mechanics mean we see them almost edge on for a few months. Cassini to teh rescue.

[Kickaha]

Originally Posted by curiousuburb Earthbound observers will miss the Rings for a while, as orbital mechanics mean we see them almost edge on for a few months. Cassini to teh rescue.

Let me guess, we can't get the mechanics to hold off for a bit. Probably a union shop.



(Nice pics!)

[AWR]

Great posts, cs! Stunning stuff.

[curiousuburb]

On Aug 11th the Rings will 'vanish'.

Originally Posted by Cassini Saturn to Pull Celestial Houdini on Aug. 11 August 7,2009 In 1918, magician extraordinaire Harry Houdini created a sensation when he made a 10,000 pound elephant disappear before a mystified audience of over 5,200 at New York's famed Hippodrome theater. But a vanishing pachyderm is nothing compared to the magnificent illusion to be performed by our solar system's own sixth rock from the sun on Aug. 11. On that day, ladies and gentlemen, boys and girls, children of all ages, the planet Saturn, with no help from either Jupiter or Uranus, will make its 170,000-mile-wide ring system disappear. How does a mere gas giant planet, without the benefit of a magic wand, smoke and mirrors, or even sleeves for that matter, manage to hide an estimated 35 trillion-trillion tons of ice, dust and rock fragments? Saturn itself, perhaps adhering to the magician's code never to reveal how a trick is performed, is not talking. But fortunately for us, dear friends, Linda Spilker, deputy project scientist for the Cassini Saturn mission at NASA's Jet Propulsion Laboratory in Pasadena, Calif., is not in the magician's guild. Since Saturn's axis is tilted as it orbits the sun, Saturn has seasons, like those of planet Earth -- but each of Saturn's seasons last for over seven years. The Hubble Space Telescope took the above sequence of images about a year apart. Starting on the left in 1996 and ending on the right in 2000. Image credit: NASA/Hubble "Saturn has been performing the "ring plane crossing" illusion about every 15 years since the rings formed, perhaps as long as 4.5 billion years ago, so by now it is pretty good at it," said Spilker. "The magician's tools required to perform this trick are pure sunlight, a planet that wobbles, and a main ring system that may be almost 200-thousand miles wide, but only 30 feet thick." ... continues ...

On the upside, the optical effect means shadows will reveal new discoveries...

Cassini spots new moonlet

NASA’s Cassini spacecraft has discovered a new object in Saturn’s rings. By capitalizing on the angle of sunlight cast on the rings as the planet nears its August 11 equinox, Cassini captured the 25-mile long shadow cast on Saturn’s B ring by a tiny moonlet that is probably around 1,300 feet in diameter. It’s no coincidence that the spacecraft’s rendezvous with the planet coincides with its equinox, which occurs twice a Saturn year, or every 15 Earth years. The mission was planned to take advantage of the 27 months during which the sun is directly over the planet’s equator at noon. This positioning causes any three-dimensional object to cast a long shadow and stand out. Because Saturn’s main rings, A, B, C and D, are a scant 30 feet thick, Cassini’s cameras can’t even see them, which makes it tough to spot anything sticking out from them. The equinox is the only time these objects will be plainly visible.

[Bryson]

Wait, that's no moon.



Edit: Dammit! Low-res version of the same on page one of this thread! And I searched and everything. Move on, nothing to see here. Except a giant planet-destroying space station, obviously.