Jupiter: the "King" and His Moons

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Inizio > SOLAR SYSTEM > Jupiter: the "King" and His Moons

Europa-PIA00578.jpgIce "floes" on Europa52 visiteJupiter's moon Europa, as seen in this image taken June 27, 1996 by NASA's Galileo spacecraft, displays features in some areas resembling ice floes (--->banchise) seen in Earth's Polar Seas. Europa has an icy crust that has been severely fractured, as indicated by the dark linear, curved, and wedged-shaped bands seen here. These fractures have broken the crust into plates as large as 30 Km (approx. 18,5 miles) across. Areas between the plates are filled with material that was probably icy slush contaminated with rocky debris. Some individual plates were separated and rotated into new positions. Europa's density indicates that it has a shell of water ice thicker than 100 Km, parts of which could be liquid. Currently, water ice could extend from the surface down to the rocky interior, but the features seen in this image suggest that motion of the disrupted icy plates was lubricated by soft ice or liquid water below the surface at the time of disruption. This image covers part of the Equatorial Region of Europa.

Europa-PIA00723.jpgBeautiful Europa...52 visiteThis global view of Europa shows the location of a four-frame mosaic of images taken by NASA's Galileo spacecraft, set into low-resolution data obtained by the Voyager spacecraft in 1979. Putting new data into its surrounding context is a technique that allows scientists to better understand features observed on planetary surfaces. The Galileo spacecraft obtained these images during its first orbit of Jupiter at a distance of about 156.000 km (such approx. 96.300 miles) on June 27, 1996. The finest details that can discerned in this picture are about 1,6 Km (1 mile) across. North is to the top.

Europa-PIA00874-PCF-LXTT.jpgEuropa's Leading Hemisphere (Absolute Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga - Lunexit Team)117 visitenessun commentoMareKromium

Europa-PIA00874.jpgEuropa's Leading Hemisphere52 visiteThis image of Europa's Leading Hmisphere was obtained by the Solid State Imaging (CCD) System on board NASA's Galileo spacecraft during its seventh orbit of Jupiter. In the upper left part of the image is Tyre, a multi-ringed structure that may have formed as a result of an ancient impact. Also visible are numerous lineaments that extend for over 1000 Km. The limb, or edge, of Europa in this image can be used by scientists to constrain the radius and shape of the satellite. North is to the top of the picture and the Sun illuminates the surface from the right. The image, centered at -40° Latitude and 180° Longitude, covers an area approx. 2000 by 1300 Km. The finest details that can be discerned in this picture are about 6,6 Km across. The images were taken on April 3, 1997 at 17 h, 42', 19" Universal Time when the spacecraft was at a range of about 318.000 Km from Europa.

Europa-PIA01101.jpgWhen the Sun sets...On Europa52 visiteThis image of Europa was taken by the Galileo spacecraft under "low-Sun" illumination - the equivalent of taking a picture from a high altitude at Sunrise or Sunset. Note that in this image the topography of the terrain is emphasized. Planetary geologists use information from images acquired under a variety of lighting conditions to identify different types of structures and interpret how they formed. For example, the length of the shadow cast by a feature (e.g. a ridge or knob) is indicative of that feature's height. In this recent image, ridges and irregularly shaped knobs ranging in size from 5 Km across down to the limit of resolution (0,44 Km/pixel) can be seen. Measurements from shadow lengths indicate that features in this image range from tens of meters up to approx. 100 mt in height. The Galileo spacecraft acquired this image of Europa's surface during its 3rd orbit around Jupiter. The image covers an area of approx. 40 by 75 Km, centered near 10° South and 190° West.

Europa-PIA01126.jpgEuropa's Lanscape (HR)54 visiteThis mosaic shows some of the highest resolution images obtained by the Solid State Imaging (SSI) System on NASA's Galileo spacecraft during its 11th orbit around Jupiter. North is to the top of the image. The Sun illuminates the scene from the left, showing hundreds of ridges that cut across each other, indicating multiple episodes of ridge formation either by volcanic or tectonic activity within the ice. Also visible in the image are numerous isolated mountains or "massifs". The highest of these, located in the upper right corner and lower center of the mosaic, are approx. 500 mt (about 1.640 feet) high. Irregularly shaped areas where the ice surface appears to be lower than the surrounding plains (e.g., in the left-center and lower left corner of the mosaic) may be related to the "chaos" areas of iceberg-like features seen in earlier SSI images of Europa.
The mosaic, centered at 35,4° North Lat. and 86,8° West Long., covers an area of 108 by 90 Km (about 66 x 55 miles).
The smallest distinguishable features in the image are about 68 meters (223 feet) across. These images were obtained on November 6, 1997, when the Galileo spacecraft was approximately 3,250 kilometers (1,983 miles) from Europa.

Europa-PIA01144.jpgCold, cold world...52 visiteThis infrared image of Europa, showing heat radiation from its surface at a wavelength of 27 microns (millionths of a meter), provides the best view yet of Europa's daytime temperatures. Temperatures, derived from the brightness of the infrared radiation, can be determined from the colors by reference to the scale at the bottom of the image. The image, taken by Galileo spacecraft, shows the full disk of Europa, highly distorted by the relative motion of Europa and the spacecraft, centered on longitude 190°, with North at the top. The data show that midday temperatures at Europa's Equator reach about 130° Kelvin (-225 F). The surface is even colder toward the Poles and before or after midday.
Small patches of different colors on Europa's disk show regions that are warmer or cooler than their immediate surroundings: the warm patches are generally relatively dark and thus absorb more sunlight, than neighboring Regions, while the cool patches are relatively bright. In the lower left corner, heat radiation from Jupiter itself, appearing orange-red in this representation, can be seen peeking out from behind Europa's disk.

The image was taken with Galileo's PPR (Photopolarimeter-Radiometer) instrument on the spacecraft's seventh orbit around Jupiter, from a range of about 65,000 kilometers (40,389 miles). Surface temperatures derived from the strength of infrared radiation, as was done here, are called "brightness temperatures", and may be slightly in error.

The PPR instrument builds up an image by slowly scanning across the target over a period of up to one hour. The motion of Galileo relative to Europa during this time causes distortions in the satellite shape on the image, which therefore does not appear circular. The small overlapping circles that make up the image show the size of the area, about 160 kilometers (99 miles) across, covered by each individual PPR measurement. Blue spots in the dark sky in the right-hand portion of the image are due to noise.

Europa-PIA01212.jpgEuropa's terminator103 visiteThis image of Europa was obtained by the Solid State Imaging (CCD) System on board NASA's Galileo spacecraft during its 4th orbit of Jupiter. Linear features with bright central stripes referred to as "Triple Bands" (TB) are seen to transect the surface of Europa. Several of these TBs are over 700 Km in length. In the left side of the image the surface of Europa is seen to be locally pitted and irregular. Ridges less than 100 Km in length are also visible in this Region.
The area seen in this image, centered near 27° South and 300° West, is 760 (456 miles) by 850 Km (510 miles) across, which is approximately the size of the state of Texas or the country of France. North is to the top of the image, with the sun illuminating the surface from the left. The image which has a resolution of 1,3 Km per picture element (e cioè "per pixel") was obtained on December, 19th, 1996.

Europa-PIA01295.jpgEuropa in natural colors (Sn) and enhanced colors (Dx)61 visiteThis color composite view combines violet, green, and infrared images of Jupiter's intriguing moon, Europa, for a view of the moon in natural color (left) and in enhanced color designed to bring out subtle color differences in the surface (right). The bright white and bluish part of Europa's surface is composed mostly of water ice, with very few non-ice materials. In contrast, the brownish mottled regions on the right side of the image may be covered by hydrated salts and an unknown red component. The yellowish mottled terrain on the left side of the image is caused by some other unknown component. Long, dark lines are fractures in the crust, some of which are more than 3,000 kilometers (1,850 miles) long.
North is to the top of the picture and the sun fully illuminates the surface. Europa is about 3,160 kilometers (1,950 miles) in diameter, or about the size of Earth's moon. The finest details that can be discerned are 25 kilometers across. The images in this global view were taken in June 1997 at a range of 1.25 million kilometers by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft, during its ninth orbit of Jupiter.

Europa-PIA01401.jpgThe frozen Ocean of Europa53 visiteThis complex area on the side of Europa which faces away from Jupiter shows several types of features that are formed by disruptions of Europa's icy crust. North is to the top of the image, taken by NASA's Galileo spacecraft, and the Sun illuminates the surface from the left. The prominent wide, dark bands are up to 20 Km (about 12 miles) wide and over 50 Km (appx. 30 miles) long. They are believed to have formed when Europa's icy crust fractured, separated and filled in with darker, "dirtier" ice or slush from below. A relatively rare type of feature on Europa is the 15-Km-diameter (about 9,3-mile) impact crater in the lower left corner. The small number of impact craters on Europa's surface is an indication of its relatively young age. A region of chaotic terrain south of this impact crater contains crustal plates which have broken apart and rafted into new positions. Some of these "ice rafts" are nearly 1 Km (about 1/2 a mile) across.
Other regions of chaotic terrain are visible and indicate heating and disruption of Europa's icy crust from below. The youngest features in this scene are the long, narrow cracks in the ice which cut across all other features. One of these cracks is about 30 kilometers (18 miles) to the right of the impact crater and extends for hundreds of miles from the top to the bottom of the image.

Europa-PIA01404.jpgConamara Chaos Region (HR)52 visiteThis HR view of the Conamara Chaos Region on Jupiter's moon Europa, reveals craters which range in size from about 30 to over 450 mt (slightly over 1/4 of a mile) in diameter. The large number of craters seen here is unusual for Europa. This section of Conamara Chaos lies inside a bright ray of material which was ejected by the large impact crater, Pwyll, about 1000 Km (620 miles) to the South. The presence of craters within the bright ray suggests that many are secondaries which formed from chunks of material that were thrown out by the enormous energy of the impact which formed Pwyll. North is to the upper right of the picture and the Sun illuminates the surface from the East. The image, centered at 9° Latitude and 274° Longitude, covers an area of approx. 8 by 4 Km (such as about 5 by 2,5 miles). The finest details that can be discerned in this picture are about 20 mt (66 feet) across. The images were taken on December 16, 1997 from a distance of 960 Km from Europa.

Europa-PIA01405.jpgDark Region on Europa52 visiteThis view taken by NASA's Galileo spacecraft of Jupiter's icy moon Europa focuses on a dark, smooth Region whose center is the lowest area in this image. To the West (left), it is bounded by a cliff and terraces, which might have been formed by normal faulting. The slopes toward the East (right) leading into the dark spot are gentle. Near the center of the dark area, it appears the dark materials have covered some of the bright terrain and ridges. This suggests that when the dark material was deposited, it may have been a fluid or an icy slush. Only a few impact craters are visible, with some of them covered or flooded by dark material. Some appear in groups, which may indicate that they are secondary craters formed by debris excavated during a larger impact event. A potential source for these is the nearby crater Mannann`an.
North is to the top of the picture which is centered at 1° South Latitude and 225° West Longitude. The images in this mosaic have been re-projected to 50 mt/pixel.

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