Cassini spacecraft obtains best views of Saturn hexagon
NASA’s Cassini spacecraft has obtained the highest-resolution movie yet of a unique six-sided jet stream, known as the hexagon, around Saturn’s north pole.
This is the first hexagon movie of its kind, using color filters, and the first to show a complete view of the top of Saturn down to about 70 degrees latitude. Spanning about 20,000 miles (30,000 kilometers) across, the hexagon is a wavy jet stream of 200-mile-per-hour winds (about 322 kilometers per hour) with a massive, rotating storm at the center. There is no weather feature exactly, consistently like this anywhere else in the solar system.
"The hexagon is just a current of air, and weather features out there that share similarities to this are notoriously turbulent and unstable," said Andrew Ingersoll, a Cassini imaging team member at the California Institute of Technology in Pasadena. "A hurricane on Earth typically lasts a week, but this has been here for decades—and who knows—maybe centuries."…
From scientist’s understanding of fluid dynamics, Jupiter’s famous Great Red Spot should have disappeared many centuries ago. It has been losing energy by radiating heat and experiences much turbulence which drains the energy of the spot’s winds. So why has it survived for so long?
Pedram Hassanzadeh who is a postdoctoral fellow at Harvard University and Philip Marcus, a professor of fluid dynamics at the University of California have built their own model to try and explain why, and according to their research, the secret lies in the vertical motion of the Red Spot: ”As the vortex loses energy, the vertical flow transports hot gases from above and cold gases from below the vortex toward its center, restoring part of its lost energy.” (phys.org, 13th Nov 2013)
Both scientists are aware that their model is not complete and cannot completely explain the life of the spot however "they believe the occasional absorption of smaller vortices, consistent with observation, may provide the extra energy needed for hundreds of years of life. They have begun modifying their computer model to test this thesis.” (phys.org, 13th Nov 2013)
Read the full article here on the phys.org website
This scene shows a section of Ismeniae Fossae that straddles the southern highlands–northern lowlands of Mars. The 2 km-wide curvilinear trough that runs through this image contains numerous parallel grooves and ridges comprising material from the trough walls and material that has been dragged along the floor by ancient glaciers and ice-rich flows.
In the left portion of the scene the channel truncates a roughly 25 km-wide crater. Material in the crater walls has slumped down into the channel, smoothing over the grooved floor. Around this crater, and elsewhere in Ismeniae Fossae, clusters of circular to elliptical, partially interconnected depressions are observed. These may be either secondary impact craters from debris flung out by larger impact craters, or collapse pits caused by the sublimation of subsurface ice…
A quintet of Saturn’s moons dance elegantly above the planet’s famed rings in this photo taken by the Cassini spacecraft and released November 4.In orbit around the ringed planet since 2004, Cassini has offered unparalleled views of Saturn’s rings and moons, including this picture shot from slightly above the plane of the rings.
On the right, the closest moon is Rhea, which is Saturn’s second-largest satellite, and in the center is Enceladus, shining brightly with frost vented from its south pole geysers.
Kepler Telescope Finds Plethora of Earth-Size Planets
NASA’s premier planet-hunting scope turns up 647 possible Earth-size worlds in the Milky Way
By Clara Moskowitz
A little more than two decades ago, no planets had ever been detected outside the solar system. Now, more than 1,000 extrasolar planets have been confirmed, and on Monday the team behind the Kepler Space Telescope announced a haul of 833 more candidate planets to consider adding to the tally.
This embarrassment of riches is far beyond what scientists dared to hope for before NASA launched the Kepler mission in 2009. The telescope, in permanent orbit around the sun, identifies planets by watching them “transit,” or pass in front of, their stars, briefly dimming the stars’ light. “When I first started working with Kepler right before launch, I thought there would be maybe a thousand planets that Kepler would find,” Jason Rowe, an astronomer at the Search for Extraterrestrial Intelligence Institute in Mountain View, Calif., said during a press conference Monday at the Kepler Science Conference in Moffett Field, Calif.
In actuality, Kepler has uncovered more than 3,500 candidate exoplanets in its first three years, including large and small planets, rocky and gaseous worlds, and a total of 647 possible planets that appear to be Earth-sized…
Terra-Forming: Should We Remake Mars in Earth’s Image?
by Ray Villard
We will eventually have the technology to make Mars a more habitable planet — but for whom? Earthlings, or Martians?
By definition, Mars terraforming would make it more Earth-like. Alternatively, Mars renovation would seek to resuscitate any native life that might have survived in environmental niches for billions of years. Astrobiologist Chris McKay, of NASA’s Ames Research Center, favors a non-geocentric term: planetary ecosynthesis, for establishing a robust biosphere on a planet’s surface.
Mars is certainly a prize for colonization. The Red Planet has as much surface area as all of Earth’s continents combined, making it the focus of several grassroots space pioneering groups.
But this presents a conundrum. McKay asks if a biologically rich and diverse Mars is more valuable than largely preserving the beautiful, but seemingly dead, world we are exploring today…
(Phys.org) —With the sun now shining down over the north pole of Saturn’s moon Titan, a little luck with the weather, and trajectories that put the spacecraft into optimal viewing positions, NASA’s Cassini spacecraft has obtained new pictures of the liquid methane and ethane seas and lakes that reside near Titan’s north pole. The images reveal new clues about how the lakes formed and about Titan’s Earth-like “hydrologic” cycle, which involves hydrocarbons rather than water… (read more)
Image: NASA/JPL-Caltech/University of Arizona/Univ. of Idaho
This portrait looking down on Saturn and its rings was created from images obtained by NASA’s Cassini spacecraft on Oct. 10, 2013. It was made by amateur image processor and Cassini fan Gordan Ugarkovic. This image has not been geometrically corrected for shifts in the spacecraft perspective and still has some camera artifacts.
The mosaic was created from 12 image footprints with red, blue and green filters from Cassini’s imaging science subsystem. Ugarkovic used full color sets for 11 of the footprints and red and blue images for one footprint.
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 mission for NASA’s Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo. For more information about the Cassini-Huygens mission visit http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov.
It’s been a long time since anyone paid ice giant Uranus a visit. Only one spacecraft has been there: Voyager 2 in 1986, which sped past the planet when it was oriented pole-on to the Sun.
Unlike Jupiter and Saturn with their numerous distinct cloud bands and churning storms, Uranus presented an almost featureless pale blue disk to Voyager. Processing of the images reveals a few discrete clouds, but at first appearance, the planet was disappointingly bland.
Two key things have happened since the Voyager 2 encounter to dramatically change our perception of this planet. As equinox approached in 2007, the atmosphere became more active. Second, our ability to observe Uranus from Earth, has undergone a revolution. Adaptive optics now allow numerous atmospheric features to be tracked, revealing the planet to be much more similar to Jupiter and Saturn in appearance when it’s heated at lower latitudes…
(Phys.org) —An international team of astronomers has discovered an exotic young planet that is not orbiting a star. This free-floating planet, dubbed PSO J318.5-22, is just 80 light-years away from Earth and has a mass only six times that of Jupiter. The planet formed a mere 12 million years ago—a newborn in planet lifetimes… (read more)
Big calderas point to early magma outbursts that shaped the red planet.
by Dan Vergano
Massive “supervolcanoes” erupted across the northern face of Mars some 3.7 billion years ago, planetary scientists suggest. The eruptions likely blasted lava, sulfur, and ash across the red planet, altering its atmosphere and surface.
The planets of the inner solar system—Earth, Mars, Venus, and Mercury—started their lives as boiling-hot balls of rock, which cooled to feature thin crusts battered by asteroid and comet impacts. On Mars, that early crust was perhaps also punctured by supersize volcanoes with calderas more than 30 mi (50 km) wide, a newly identified kind of volcanism on the red planet…
Carlson reported that new methods for dating rocks from the Moon’s crust or regolith have placed its birth between 4.4 and 4.45 billion years ago. Previously, scientists placed its origin at 4.56 billion years ago. The Moon was formed when a Mars-sized body smashed into the Earth, reducing part of our planet to liquid rock and shooting debris into orbit that slowly cooled and coalesced into the Moon…
This composite is assembled from separate images of Jupiter and comet Shoemaker-Levy 9, as imaged by the NASA/ESA Hubble Space Telescope in 1994. Comet Shoemaker-Levy 9 was discovered by astronomers Carolyn and Eugene M. Shoemaker and David Levy on 24 March 1993. It was the first comet observed to be orbiting a planet — in this case, Jupiter — rather than the sun. The effect of Jupiter’s tidal forces tore the comet apart on its approach and, eventually, the fragments collided with Jupiter between 16 and 22 July 1994.
The image of the comet, showing 21 fragments, was taken on 17 May 1994. The image of Jupiter was taken on 18 May 1994; the dark spot on the planet’s disc is the shadow of the inner moon lo. The apparent angular size of Jupiter relative to the comet and its angular separation from the comet when the images were taken have been modified for illustration purposes.
Image: NASA, ESA, H. Weaver & E. Smith (STScI) and J. Trauger & R. Evans (Jet Propulsion Laboratory) [high-resolution]
Squinting At Saturn Through 17th Century Technology
by Amanda Alvarez
A team of French researchers has shed light on an important moment of astronomical history by testing the old lenses used by astronomer Jean-Dominique Cassini when he observed a minuscule gap between two of Saturn’s rings in 1675. Questions have lingered over whether it was possible to see this gap, which was later named the “Cassini Division,” with the optics he had at his disposal.
"I don’t think I’ve ever been able to see the Cassini Division clearly with my own backyard telescope," said Laird Close, an astronomer at the University of Arizona’s Steward Observatory. The 3000-mile wide gap “is not a trivial thing to see.”
At its closest, Saturn is nearly 750 million miles from Earth. At this distance, the Cassini Division has an angular size of 0.65 seconds of arc, or about 3,000 times smaller than the moon, which spans about half a degree of visual angle…