Jupiter: the "King" and His Moons
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Jupiter_Storm.jpgThe Dark S.E.B. of Jupiter is back!97 visiteDalla Rubrica "NASA - Picture of the Day" del giorno 29 Npvembre 2010:"Why are planet-circling clouds disappearing and reappearing on Jupiter?
Although the ultimate cause remains unknown, planetary meteorologists are beginning to better understand what is happening. Earlier this year, unexpectedly, Jupiter's Dark Southern Equatorial Belt (SEB) disappeared. The changes were first noted by amateurs dedicated to watching Jupiter full time. The South Equatorial Band has been seen to change colors before, although the change has never been recorded in such detail. Detailed professional observations revealed that high-flying light-colored Ammonia-based clouds formed over the planet-circling Dark Belt. Now those Light Clouds are dissipating, again unveiling the lower Dark Clouds.
Pictured above two weeks ago, far InfraRed images - depicted in false-color red - show a powerful storm system active above the returning Dark Belt. Continued observations of Jupiter's current cloud opera, and our understanding of it, is sure to continue".MareKromium
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Jupiter_from_New_Horizons-092606_1_hr.jpgJupiter, from New Horizons89 visiteBlazing along its path to Pluto, NASA's New Horizons has come within hailing distance of Jupiter. The first picture of the Giant Planet from the spacecraft's Long Range Reconnaissance Imager (LORRI), taken Sept. 4, 2006, is a tantalizing promise of what's to come when New Horizons flies through the Jupiter system early next year.
New Horizons was still 291 MKM (nearly 181 MMs) away from Jupiter when LORRI took the photo.
As New Horizons comes much closer, next January and February 2007, LORRI will take more-detailed images.
"These first LORRI images of Jupiter are awe-inspiring," says New Horizons Project Scientist Hal Weaver, of the Johns Hopkins University Applied Physics Laboratory (APL), where LORRI was designed and built. "New Horizons is speeding toward this majestic planet at 45,000 miles per hour, right on target for a close encounter on February 28 of next year. LORRI's resolution at Jupiter will be 125 times better than now, and we're really looking forward to getting the most detailed views of the Jovian system since Cassini's flyby in late 2000 and Galileo's final images in 2003."
Now on the outskirts of the asteroid belt, LORRI snapped this image during a test sequence to help prepare for the Jupiter encounter observations. It was taken close to solar opposition, meaning that the Sun was almost directly behind the camera when it spied Jupiter. This makes Jupiter appear blindingly bright, about 40 times brighter than Pluto will be for LORRI's primary observations when New Horizons encounters the Pluto system in 2015. To avoid saturation, the camera's exposure time was kept to 6 milliseconds. This image was, in part, a test to see how well LORRI would operate with such a short exposure time.
"LORRI's first Jupiter image is all we could have expected," says LORRI Principal Investigator Andy Cheng, of APL. "We see belts, zones and large storms in Jupiter's atmosphere. We see the Jovian moons Io and Europa, as well as the shadows they cast on Jupiter. It is most gratifying to detect these moons against the glare from Jupiter."
LORRI wasn't the only New Horizons instrument peeking at Jupiter on Sept. 4; the Ralph imager also performed some important calibrations. "We rapidly scanned Ralph's Multispectral Visible Imaging Camera [MVIC] across Jupiter to test a technique we plan to employ near closest approach next February. We also observed Jupiter in the infrared using Ralph's Linear Etalon Imaging Spectral Array [LEISA]," says Ralph Program Manager Cathy Olkin, of the Southwest Research Institute. "Everything worked great."
New Horizons won't observe Jupiter again until early January 2007, when periodic monitoring will begin, followed by intensive observations at the end of February. The spacecraft will also continue to look at the Jovian magnetosphere for several months after closest approach.
"New Horizons is headed to a spectacular science encounter with the Jupiter system early next year," says mission Principal Investigator Alan Stern, of the Southwest Research Institute. "The first LORRI images of Jupiter just whet our appetite for the observations to come."
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Jupiter_s Aurora-HST-PIA03155_modest.jpgJupiter's Aurora - HST103 visiteCaption NASA originale:"Auroras are curtains of light resulting from high-energy electrons racing along the planet's magnetic field into the upper atmosphere.
The electrons excite atmospheric gases, causing them to glow.
The image shows the main oval of the aurora, which is centered on the magnetic north pole, plus more diffuse emissions inside the polar cap. The HST image shows also unique emissions from the magnetic "footprints" of 3 of Jupiter's largest moons.
Auroral footprints can be seen in this image from Io (along the lefthand limb), Ganymede (near the center), and Europa (just below and to the right of Ganymede's auroral footprint).
These emissions, produced by electric currents generated by the satellites, flow along Jupiter's magnetic field, bouncing in and out of the upper atmosphere".
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Jupiter_s New Spot.jpgThe "New Red Spot" of Jupiter75 visiteJupiter's "Great Red Spot" is a swirling storm seen for over 300 years, since the begining of telescopic observations of the Solar System's ruling gas giant. But over the last month, the Great Red Spot has been joined by a new one (informally named "Red Spot Jr."). Thought to be similar to the Great Red Spot itself, this smaller Red Spot was actually seen to form as smaller whitish oval-shaped storms merged and then developed the remarkable reddish hue. This webcam image showing the two red tinted Jovian storms was recorded on the morning of March 12, 2006, from the Central Coast of New South Wales, Australia - part of a series showing Jupiter's rotation. Similar in diameter to planet Earth, Red Spot Jr. is expected to last for a while and trails the Great Red Spot by about an hour as the Planet rotates. Astronomers still don't exactly understand why Jupiter's red spots...are red.
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Jupiter_s NorthPole-PIA07783.jpgThe North Pole of Jupiter84 visiteThe South Polar Regions shown here are less clearly visible because Cassini viewed them at an angle and through thicker atmospheric haze.
The round maps are polar stereographic projections that show the North or South Pole in the center of the map and the Equator at the edge.
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Jupiter_s Rings-PIA01529_modest.jpgColorful Jupiter's Rings880 visiteCaption NASA originale:"Jupiter's faint ring system is shown in this color composite as two light orange lines protruding from the left toward Jupiter's limb. This picture was taken in Jupiter's shadow through orange and violet filters. The colorful images of Jupiter's bright limb are evidence of the spacecraft motion during these long exposures. The Voyager 2 spacecraft was at a range of 1.450.000 kilometers about two degrees below the plane of the ring. The lower ring image was cut short by Jupiter's shadow on the ring itself".
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Jupiter_s Rings-PIA01627.jpgThe Rings of Jupiter (1)65 visiteOriginal caption:"This schematic cut-away view of the components of Jupiter's Ring System shows the geometry of the Rings in relation to Jupiter and to the small inner moons, which are the source of the dust forming the Rings themselves. The innermost and thickest Ring, shown in gray shading, is the halo that ends at the Main Ring. The thin, narrow Main Ring, shown with red shading, is bounded by the 16- Km-wide (10-miles) satellite Adrastea and shows a marked decrease in brightness near the orbit of Jupiter's innermost moon, Metis. It is composed of fine particles knocked off Adrastea and Metis. Although the orbits of Adrastea and Metis are about 1000 Km (about 600 miles) apart, that separation is not depicted in this drawing. Impacts by small meteoroids (fragments of asteroids and comets) into these small, low-gravity satellites feed material into the Rings. Thebe and Amalthea, the next 2 moons in increasing distance from Jupiter, supply dust which forms the thicker, disk-like 'Gossamer' Rings".
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Jupiter_s Rings-PIA01628.jpgThe Rings of Jupiter (2)64 visiteScientists studying data from Galileo spacecraft have found that the Ring System is made up of impact debris created when meteoroids, which are fragments of comets and asteroids, slam into Jupiter`s four smallest satellites. The top panel shows that the Main Ring (red) is formed mostly from meteoroid impact debris kicked up from the innermost moons, Metis (m) and Adrastea (a). Since both satellites orbit in paths not inclined to Jupiter's equator, the Main Ring appears as a narrow line. The middle panel shows the additional effect of dust ejected from the satellite Amalthea (A), responsible for producing 1 of the 2 moon components of the Gossamer Ring. Amalthea's orbit is inclined to Jupiter's equatorial plane and at different times the satellite's vertical position can range anywhere between the 2 extreme limits shown. Dust ejected from Amalthea (orange) produces a ring whose thickness equals Amalthea's vertical projections beyond Jupiter's equatorial plane. The lower panel shows the additional effect of dust ejected from Thebe (T), which makes up the second component (shown in green) of the gossamer ring. Again, the two positions shown represent the maximum projections of Thebe from Jupiter's equatorial plane. This component of the gossamer ring is thicker than the component due to Amaltheas dust because Thebe's orbit is more inclined than that of Amalthea.
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Jupiter_s SouthPole-PIA07784.jpgThe South Pole of Jupiter64 visiteThe South Polar Regions shown here are less clearly visible because Cassini viewed them at an angle and through thicker atmospheric haze.
The round maps are polar stereographic projections that show the North or South Pole in the center of the map and the Equator at the edge.
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Jupiter_s System-PIA01481.jpgJupiter's (Main) System86 visiteCaption NASA originale:"Jupiter and its four planet-size moons, called the Galilean Satellites, were photographed in early March by Voyager 1 and assembled into this collage. They are not to scale but are in their relative positions. (...) Nine other much smaller satellites circle Jupiter, one inside Io's orbit and the other millions of miles from the Planet.
Not visible is Jupiter's faint ring of particles, seen for the first time by Voyager 1".
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Jupiter_s limb-Gal-PIA00858_modest.jpgJupiter's limb and White Ovals, from Galileo62 visiteCaption NASA originale:"The oval shaped vortices in the upper half of the mosaic are two of the three long-lived White Ovals that formed to the south of the Red Spot in the 1930's and, like the Red Spot, rotate in a counterclockwise sense. The east to west dimension of the leftmost White Oval is 9000 Km. The White Ovals drift in longitude relative to one another, and are presently restricting the cyclonic structure. To the south, the smaller oval and its accompanying cyclonic system are moving eastward at about 0.4 degrees per day relative to the larger ovals. The interaction between these two cyclonic storm systems is producing high, thick cumulus-like clouds in the southern part of the more northerly trapped system".
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Jupiter_s limb-Gal-PIA00896_modest.jpgJupiter's limb, from Galileo78 visiteCaption NASA originale:"North is at the top. The images are projected on a sphere, with features being foreshortened towards the north. The planetary limb runs along the right edge of the mosaic. Cloud patterns appear foreshortened as they approach the limb. The smallest resolved features are tens of kilometers in size. These images were taken on April 3, 1997, at a range of 1.4 MKM by the Solid State Imaging system (CCD) on NASA's Galileo spacecraft".
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