Jupiter: the "King" and His Moons
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Jupiter_s System-PIA01481.jpgJupiter's (Main) System61 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 Galileo53 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 Galileo66 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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Jupiter_sMap00-PIA07782-1.jpgSuper-detailed Jupiter's Map (1)57 visiteThis map is part of a group release of cylindrical and polar stereographic projections of Jupiter.
This color map of Jupiter were constructed from images taken by the narrow-angle camera onboard NASA's Cassini spacecraft on Dec. 11 and 12, 2000, as the spacecraft neared Jupiter during its flyby of the giant planet. Cassini was on its way to Saturn. They are the most detailed global color maps of Jupiter ever produced. The smallest visible features are about 120 Km (approx. 75 miles) across.
The maps are composed of 36 images: a pair of images covering Jupiter's Northern and Southern Hemispheres was acquired in two colors every hour for nine hours as Jupiter rotated beneath the spacecraft. Although the raw images are in just two colors, 750 nanometers (near-infrared) and 451 nanometers (blue), the map's colors are close to those the human eye would see when gazing at Jupiter.
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Jupiter_sMap00-PIA07782-2.jpgSuper-detailed Jupiter's Map (2)59 visiteThe map shows a variety of colorful cloud features, including parallel reddish-brown and white bands, the Great Red Spot - frame 1), multi-lobed chaotic regions, white ovals and many small vortices. Many clouds appear in streaks and waves due to continual stretching and folding by Jupiter's winds and turbulence. The bluish-gray features along the north edge of the central bright band are equatorial "hot spots" meteorological systems such as the one entered by NASA's Galileo probe. Small bright spots within the orange band north of the Equator are lightning-bearing thunderstorms. The Polar Regions are less clearly visible because Cassini viewed them at an angle and through thicker atmospheric haze.
Pixels in the rectangular map cover equal increments of planetocentric latitude (which is measured relative to the center of the Planet) and longitude, extending to 180° of latitude and 360° of longitude.
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Jupiter_s_Aurorae.jpgJovian Aurorae53 visiteNASA's HST has recently taken images of Jupiter in support of the New Horizons Mission. The images were taken with Hubble's Wide Field Planetary Camera 2 and the Advanced Camera for Surveys. Hubble will continue to photograph Jupiter, as well as its volcanically active moon, Io, over the next month as the New Horizons spacecraft flies past Jupiter. New Horizons is en route to Pluto, and made its closest approach to Jupiter on February 28, 2007. Through combined remote imaging by Hubble and in situ measurements by New Horizons, the two missions will enhance each other scientifically, allowing scientists to learn more about the Jovian atmosphere, the Aurorae, and the charged-particle environment of Jupiter and its interaction with the Solar Wind.
For this photo, the combined ultraviolet- and visible-light images of Jupiter were taken with Hubble from February 17-21. The image segments in the boxes, obtained using the Advanced Camera for Surveys's ultraviolet camera, show auroral emissions that are always present in Jupiter's polar regions. The equatorial regions of Jupiter were imaged in blue light by the Wide Field Planetary Camera 2. Cloud features in Jupiter's main atmosphere are revealed. In the ultraviolet views, the atmosphere looks more hazy because sunlight is reflected from higher in the atmosphere.MareKromium
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Jupiter_sofiawesley.jpgJupiter from the Stratosphere145 visiteDalla Rubruica "NASA - Picture of the Day", del giorno 3 Giugno 2010:"SOFIA, the Stratospheric Observatory for InfraRed Astronomy, captured its "first light" images on May 26, from an altitude of 35.000 feet.
While flying above most of planet Earth's InfraRed-absorbing water vapor, SOFIA's premier IR views of the cosmos included this remarkable false-color image (right panel) of Jupiter.
For comparison, on the left is a recent, ground-based visible light image. Both show our Solar System's ruling gas giant without its dark Southern Equatorial Belt (normally seen in the upper Hemisphere in this orientation). That familiar feature faded from view early in May. But the bright white stripe in SOFIA's image is a region of Jupiter's clouds transparent to IR Light, offering a glimpse below the cloud tops".MareKromium
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Jupitercrescent_cassini_big.jpgJupiter from Cassini65 visiteLa "falce" di un Giove crescente, ripresa dalla Sonda Cassini mentre si avvicinava e si apprestava ad effettuare il "fly-by" del Gigante Gassoso.
Una splendida immagine che ci ricorda alcune sequenze del capolavoro di Stanley Kubrick, "2001 - A Space Odyssey" in cui Giove appariva agli occhi di Dave Bowman proprio come lo vediamo in questo frame.
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Jupiter~0.jpgThe "true" colors of Jupiter (an interpretation)134 visiteJupiter has several narrow belts of distinct colors as well as reddish oval shaped stable cyclonic weather zones such as the 'Great Red Spot'. The overall albedo of the planet is 0,52. The colors shown in the strips are of the wider alternating belts and zones extending from either side of the often white Equatorial Zone.
This is a Voyager 1 image assembled from raw data and color balanced to approximate the colors and contrast of the Planet.
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Jupiter~1.jpgThe "Eyes" of Jupiter: a change of colors could mean a climate change?53 visiteJupiter's Great Red Spot is a swirling storm seen for over 300 years, since the beginning of telescopic observations. But in February 2006, planetary imager Christopher Go noticed it had been joined by Red Spot Jr - formed as smaller whitish oval-shaped storms merged and then developed the remarkable reddish hue. This sharp HST image showing the two salmon-colored Jovian storms was recorded in April 2006. About half the size of the original Red Spot, Red Spot Jr. is similar in diameter to planet Earth. Seen here below and left of the ancient storm system, it trails the Great Red Spot by about an hour as the planet rotates from left to right. While astronomers still don't exactly understand why Jupiter's red spots are red, they do think the appearance of Red Spot Jr. provides evidence for climate change on the Solar System's ruling Gas Giant.
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Metis-Galileo.jpgMetis (Natural Colors; credits: Ted Stryk)54 visiteMetis, o Metide, è il più interno fra i Satelliti Naturali di Giove. Appartiene al cosiddetto gruppo di Amaltea, che si compone dei piccoli satelliti interni del Pianeta. Il suo nome storico è Giove XVI.
La scoperta di Metis risale al 1979, quando fu individuato grazie alle immagini inviate a Terra dalla sonda spaziale statunitense Voyager 1 e gli venne attribuito il nome provvisorio S/1979 J3; nel 1983 l'Unione Astronomica Internazionale lo battezzò ufficialmente con il nome della titanide Metide, prima moglie di Zeus e madre di Atena secondo la Mitologia Greca.
Il colorito giallo-rossastro che è stato attribuito a questo Corpo Celeste da Ted Stryk potrebbe trovare una giustificazione negli accumuli (depositi superficiali) di Zolfo che Metis - periodicamente - "raccoglie" dallo Spazio durante i suoi passaggi ravvicinati ad Io.MareKromium
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Orbital_Resonance.gifThe "Orbital Resonance" (GIF-Movie; credits: http://fisicaondemusica.unimore.it.)53 visitePremessa: il moto di un Corpo Celeste in orbita attorno ad un altro Corpo Celeste di massa molto maggiore (ex.: un pianeta attorno ad una stella, o un satellite attorno ad un pianeta) è un "Moto Periodico Semplice" ("Moto Circolare Uniforme").
Ora, può accadere che due (o più) pianeti si trovino ad orbitare attorno alla medesima stella (o che due - o più - satelliti si trovino ad orbitare attorno al medesimo "Parent Planet") con tempi di rivoluzione (---> i "Periodi del loro Moto") i quali stanno tra loro in rapporto di due piccoli interi (come 2:1, 2:3, ecc. - si legge "due a uno", "due a tre" etc.).
In questo caso, anche la loro reciproca attrazione gravitazionale verrà ad assumere un carattere di periodicità: essa cioè aumenterà quando i due pianeti si avvicinano, e diminuirà quando essi si allontanano.
Se queste variazioni della forza attrattiva gravitazionale sentita da ciascun pianeta saranno significative per la sua orbita, questa potrà modificarsi. Ed a tal punto sarà possibile identficare due scenari:
1) il moto dei pianeti diviene instabile: le orbite cambiano lentamente finché i due corpi non si influenzano più sensibilmente. (nota: nel caso di un Corpo Celeste Maggiore ed uno minore, questo effetto si risolverà nello "scacciare" il corpo minore da certe zone dello spazio, "liberando" la strada al Corpo Maggiore)
2) i due pianeti non si avvicinano mai abbastanza da influenzarsi violentemente, e quindi entrano in risonanza stabile.
(nota: le loro orbite, in questo caso, subiranno delle modificazioni le quali verranno poi compensate - rectius: annullate - dal verificarsi di modificazioni contrarie nell'arco di ogni rivoluzione)
per maggiori info: http://fisicaondemusica.unimore.it.MareKromium
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