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| Ultimi arrivi - Jupiter: the "King" and His Moons |
Io-050107_08.jpgVolcanic Lights In the Night of Io54 visiteThis unusual image shows Io glowing in the darkness of Jupiter's shadow. It is a combination of eight images taken by the New Horizons Long Range Reconnaissance Imager (LORRI) between 14:25 and 14:55 Universal Time on February 27, 2007, about 15 hours before the spacecraft's closest approach to Jupiter. North is at the top of the image.
Io's surface is invisible in the darkness, but the image reveals glowing hot lava, auroral displays in Io's tenuous atmosphere and volcanic plumes across the moon. The three bright points of light on the right side of Io are incandescent lava at active volcanoes - Pele and Reiden (south of the equator), and a previously unknown volcano near 22 degrees north, 233 degrees west near the edge of the disk at the 2 o'clock position.
An auroral glow, produced as intense radiation from Jupiter's magnetosphere bombards Io’s atmosphere, outlines the edge of the moon’s disk. The glow is patchy because the atmosphere itself is patchy, being denser over active volcanoes. In addition to the near-surface glow, there is a remarkable auroral glow suspended 330 kilometers (200 miles) above the edge of the disk at the 2 o'clock position; perhaps this glowing gas was ejected from the new volcano below it. Another glowing gas plume, above a fainter point of light, is visible just inside Io's disk near the 6 o'clock position; this plume is above another new volcanic eruption discovered by New Horizons.
On the left side of the disk, near Io's equator, a cluster of faint dots of light is centered near the point on Io that always faces Jupiter. This is the region where electrical currents connect Io to Jupiter's magnetosphere. It is likely that electrical connections to individual volcanoes are causing the glows seen here, though the details are mysterious.
Total exposure time for this image was 16 seconds. The range to Io was 2.8 million kilometers (1.7 million miles), and the image is centered at Io coordinates 7 degrees south, 306 degrees west. The image has been heavily processed to remove scattered light from Jupiter, but some artifacts remain, such as dark patches in the background.
MareKromiumMag 02, 2007
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JupiterSystem-050107_09.jpgThe "Galilean Family" of Jupiter86 visiteThis montage shows the best views of Jupiter's four large and diverse "Galilean" satellites as seen by the Long Range Reconnaissance Imager (LORRI) on the New Horizons spacecraft during its flyby of Jupiter in late February 2007. The four moons are, from left to right: Io, Europa, Ganymede and Callisto. The images have been scaled to represent the true relative sizes of the four moons and are arranged in their order from Jupiter.
Io, 3,640 kilometers (2,260 miles) in diameter, was imaged at 03:50 Universal Time on February 28 from a range of 2.7 million kilometers (1.7 million miles). The original image scale was 13 kilometers per pixel, and the image is centered at Io coordinates 6 degrees south, 22 degrees west. Io is notable for its active volcanism, which New Horizons has studied extensively.
Europa, 3,120 kilometers (1,938 miles) in diameter, was imaged at 01:28 Universal Time on February 28 from a range of 3 million kilometers (1.8 million miles). The original image scale was 15 kilometers per pixel, and the image is centered at Europa coordinates 6 degrees south, 347 degrees west. Europa's smooth, icy surface likely conceals an ocean of liquid water. New Horizons obtained data on Europa’s surface composition and imaged subtle surface features, and analysis of these data may provide new information about the ocean and the icy shell that covers it.
New Horizons spied Ganymede, 5,262 kilometers (3,268 miles) in diameter, at 10:01 Universal Time on February 27 from 3.5 million kilometers (2.2 million miles) away. The original scale was 17 kilometers per pixel, and the image is centered at Ganymede coordinates 6 degrees south, 38 degrees west. Ganymede, the largest moon in the solar system, has a dirty ice surface cut by fractures and peppered by impact craters. New Horizons’ infrared observations may provide insight into the composition of the moon’s surface and interior.
Callisto, 4,820 kilometers (2,995 miles) in diameter, was imaged at 03:50 Universal Time on February 28 from a range of 4.2 million kilometers (2.6 million miles). The original image scale was 21 kilometers per pixel, and the image is centered at Callisto coordinates 4 degrees south, 356 degrees west. Scientists are using the infrared spectra New Horizons gathered of Callisto’s ancient, cratered surface to calibrate spectral analysis techniques that will help them to understand the surfaces of Pluto and its moon Charon when New Horizons passes them in 2015.
MareKromiumMag 02, 2007
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Io_Europa-040207.jpgIo and Europa, from New Horizons83 visiteThis beautiful image of the crescents of volcanic Io and more sedate Europa was snapped by New Horizons' color Multispectral Visual Imaging Camera (MVIC) at 10:34 UT on March 2, 2007, about two days after New Horizons made its closest approach to Jupiter.
The picture was one of a handful of the Jupiter System that New Horizons took primarily for their artistic, rather than scientific value. This particular scene was suggested by space enthusiast Richard Hendricks of Austin, Texas, in response to an Internet request by New Horizons scientists for evocative, artistic imaging opportunities at Jupiter.
This image was taken from a range of 4,6 MKM (about 2,8 MMs) from Io and 3,8 MKM (about 2,4 MMs) from Europa. Although the moons appear close in this view, a gulf of 790.000 Km (490.000 miles) separates them. The night side of Io is illuminated here by light reflected from Jupiter, which is out of the frame to the right. Europa's night side is completely dark, in contrast to Io, because that side of Europa faces away from Jupiter.
Here, Io steals the show with its beautiful display of volcanic activity. Three volcanic plumes are visible. Most conspicuous is the enormous 300-Km(190-mile) -high plume from the Tvashtar volcano at the 11 o'clock position on Io's disk. Two much smaller plumes are barely visible: one from the volcano Prometheus, at the 9 o'clock position on the edge of Io's disk, and one from the volcano Amirani, seen between Prometheus and Tvashtar along Io's Terminator (the line dividing day and night). The plumes appear blue because of the scattering of light by tiny dust particles ejected by the volcanoes, similar to the blue appearance of smoke. In addition, the contrasting red glow of hot lava can be seen at the source of the Tvashtar plume.
The images are centered at 1° North, 60° West on Io, and 0° North and 149° West on Europa.
The color in this image was generated using individual MVIC images at wavelengths of 480, 620 and 850 nanometers. The human eye is sensitive to slightly shorter wavelengths, from 400 to 700 nanometers, and thus would see the scene slightly differently. For instance, while the eye would notice the difference between the yellow and reddish brown colors of Io's surface and the paler color of Europa, the two worlds appear very similar in color to MVIC's longer-wavelength vision.
The night side of Io appears greenish compared to the day side, because methane in Jupiter's atmosphere absorbs 850-nanometer light and makes Jupiter-light green to MVIC's "eyes."
MVIC is a component of the Ralph imaging instrument. MareKromiumApr 14, 2007
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Callisto-040507.jpgCallistus, from New Horizons55 visiteThe New Horizons Long Range Reconnaissance Imager (LORRI) captured these two images of Jupiter's outermost large moon, Callisto, as the spacecraft flew past Jupiter in late February.
New Horizons' closest approach distance to Jupiter was 2,3 MKM (about 1,4 MMs), not far outside Callisto's orbit, which has a radius of 1,9 MKM (about 1,2 MMs). However, Callisto happened to be on the opposite side of Jupiter during the spacecraft's pass through the Jupiter System, so these images, taken from 4,7 MKM (about 3 MMs) and 4,2 MKM (about 2,6 MMs) away, are the closest of Callisto that New Horizons obtained.
Callisto's ancient, crater-scarred surface makes it very different from its three more active sibling satellites, Io, Europa and Ganymede. Callisto, 4800 Km (about 3000 miles) in diameter, displays no large-scale geological features other than impact craters and every bright spot in these images is a crater. The largest impact feature on Callisto, the huge basin Valhalla, is visible as a bright patch at the 10 o'clock position. The craters are bright because they have excavated material relatively rich in water ice from beneath the dark, dusty material that coats most of the surface.
The two images show essentially the same side of Callisto - the side that faces Jupiter - under different illumination conditions. The images accompanied scans of Callisto's infrared spectrum with New Horizons' Linear Etalon Imaging Spectral Array (LEISA).
The New Horizons Science Team designed these scans to study how the infrared spectrum of Callisto's water ice changes as lighting and viewing conditions change, and as the ice cools through Callisto's late afternoon.
The infrared spectrum of water ice depends slightly on its temperature, and a goal of New Horizons when it reaches the Pluto system (in 2015) is to use the water ice features in the spectrum of Pluto's moon Charon, and perhaps on Pluto itself, to measure surface temperature.
Callisto provided an ideal opportunity to test this technique on a much better-known body.
The left image, taken at 05:03 Universal Time on February 27, 2007, is centered at 5° South, 5° West, and has a Solar Phase Angle of 46°. The right image was taken at 03:25 Universal Time on February 28, 2007. It is centered at 4° South, 356° West, and has a Solar Phase Angle of 76°.MareKromiumApr 14, 2007
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Io-New_Horizons.jpgIo (HR)54 visiteCaption NASA:"Spewed from a volcano, a complex plume rises over 300 Km above the horizon of Jupiter's moon Io in this image from cameras onboard the New Horizons spacecraft. The volcano, Tvashtar, is marked by the bright glow (about 1 o'clock) at the moon's edge, beyond the terminator or night/day shadow line. The shadow of Io cuts across the plume itself. Also capturing stunning details on the dayside surface, the high resolution image was recorded when the spacecraft was 2,3 MKM from Io. Later it was combined with lower resolution color data by astro-imager Sean Walker to produce this sharp portrait of the solar system's most active moon. Outward bound at almost 23 Km-per-second, the New Horizons spacecraft should cross the orbit of Saturn in June next year, and is ultimately destined to encounter Pluto in 2015".Apr 04, 2007
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Jupiter-033007.jpgStorm Spectra55 visiteThese images, taken with the LEISA infrared camera on the New Horizons Ralph instrument, show fine details in Jupiter's turbulent atmosphere using light that can only be seen using infrared sensors. These are "false color" pictures made by assigning infrared wavelengths to the colors red, green and blue. LEISA (Linear Etalon Imaging Spectral Array) takes images across 250 IR wavelengths in the range from 1.25 to 2.5 microns, allowing scientists to obtain an infrared spectrum at every location on Jupiter. A micron is one millionth of a meter.
These pictures were taken at 05:58 UT on February 27, 2007, from a distance of 2.9 million kilometers (1.6 million miles). They are centered at 8 degrees south, 32 degrees east in Jupiter "System III" coordinates. The large oval-shaped feature is the well-known Great Red Spot. The resolution of each pixel in these images is about 175 kilometers (110 miles); Jupiter's diameter is approximately 145,000 kilometers (97,000 miles).
The image on the left is an altitude map made by assigning the color red to 1.60 microns, green to 1.89 microns and blue to 2.04 microns. Because Jupiter's atmosphere absorbs light strongly at 2.04 microns, only clouds at very high altitude will reflect light at this wavelength. Light at 1.89 microns can go deeper in the atmosphere and light at 1.6 microns can go deeper still. In this map, bluish colors indicate high clouds and reddish colors indicate lower clouds. This picture shows, for example, that the Great Red Spot extends far up into the atmosphere.
In the image at right, red equals 1.28 microns, green equals 1.30 microns and blue equals 1.36 microns, a range of wavelengths that similarly probes different altitudes in the atmosphere. This choice of wavelengths highlights Jupiter's high-altitude south polar hood of haze. The edge of Jupiter's disk at the bottom of the panel appears slightly non-circular because the left-hand portion is the true edge of the disk, while the right portion is defined by the day/night boundary (known as the terminator).
These two images illustrate only a small fraction of the information contained in a single LEISA scan, highlighting just one aspect of the power of infrared spectra for atmospheric studies.
Apr 02, 2007
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Jupiter-lor_0035089864_0x630_sci_1.jpgJupiter's Ring56 visiteDescription: Jupiter's Ring - Main Ring vertical structure including ripples
Time: 2007-03-01 21:19:04 UTC
Exposure: 3000 msec
Target: Jupiter
Range: 3,6 MKM Apr 02, 2007
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Io-032807.jpgBurning Io!54 visiteNew Horizons captured this unique view of Jupiter's moon Io with its color camera - the Multispectral Visible Imaging Camera (MVIC) - at 00:25 UT on March 1, 2007, from a range of 2,3 MKM (about 1,4 MMs). The image is centered at Io coordinates 4°South lat. and 162° West Long., and was taken shortly before the complementary Long Range Reconnaissance Imager (LORRI) photo of Io released on March 13, which had higher resolution but was not in color.
Like that LORRI picture, this processed image shows the nighttime glow of the Tvashtar volcano and its plume rising 330 kilometers (200 miles) into sunlight above Io's north pole. However, the MVIC picture reveals the intense red of the glowing lava at the plume source and the contrasting blue of the fine dust particles in the plume (similar to the bluish color of smoke), as well as more subtle colors on Io's sunlit crescent. The lower parts of the plume in Io's shadow, lit only by the much fainter light from Jupiter, are almost invisible in this rendition. Contrast has been reduced to show the large range of brightness between the plume and Io's disk.
A component of the Ralph imaging instrument, MVIC has three broadband color filters: blue (480 nanometers), red (620 nm) and infrared (850 nm); as well as a narrow methane filter (890 nm). Because the camera was designed for the dim illumination at Pluto, not the much brighter sunlight at Jupiter, the red and infrared filters are overexposed on Io's dayside. This image is therefore composed from the blue and methane filters only, and the colors shown are only approximations to those that the eye would see. Nevertheless, the human eye would easily see the red color of the volcano and the blue color of the plume.
Apr 02, 2007
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Jupiter-20070323.gifWatch Jupiter and some of His Moons rotate! (GIF-Movie)55 visiteCaption NASA:"South is toward the top in this frame from a stunning movie featuring Jupiter and moons recorded last Thursday from the Central Coast of New South Wales, Australia. In fact, three Jovian Moons and two red spots are ultimately seen in the full video as they glide around the Solar System's ruling gas giant. In the early frame above, Ganymede, the largest moon in the Solar System, is off the lower right limb of the Planet, while intriguing Europa is visible against Jupiter's cloud tops, also near the lower right. Jupiter's new Red Spot junior is just above the broad white band in the Planet's Southern (upper) Hemisphere. In later frames, as Planet and moons rotate (right to left), red spot junior moves behind Jupiter's left edge while the Great Red Spot itself comes into view from the right. Also finally erupting into view at the right, is Jupiter's volcanic moon, Io (...)".
Note: click on the frame to see the movieMar 29, 2007
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Io-lor_0034685519_0x630_sci_1.jpgIo: the "Sulphur World" from New Horizons94 visitenessun commentoMareKromiumMar 18, 2007
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Io-030107-01.jpgThe greatest Volcanic Plume in the Solar System!56 visiteThis dramatic image of Io was taken by the Long Range Reconnaissance Imager (LORRI) on New Horizons at 11:04 Universal Time on February 28, 2007, just about 5 hours after the spacecraft's closest approach to Jupiter. The distance to Io was 2.5 million kilometers (1.5 million miles) and the image is centered at 85 degrees west longitude. At this distance, one LORRI pixel subtends 12 kilometers (7.4 miles) on Io.
This processed image provides the best view yet of the enormous 290-kilometer (180-mile) high plume from the volcano Tvashtar, in the 11 o'clock direction near Io's north pole. The plume was first seen by the Hubble Space Telescope two weeks ago and then by New Horizons on February 26; this image is clearer than the February 26 image because Io was closer to the spacecraft, the plume was more backlit by the Sun, and a longer exposure time (75 milliseconds versus 20 milliseconds) was used. Io's dayside was deliberately overexposed in this picture to image the faint plumes, and the long exposure also provided an excellent view of Io's night side, illuminated by Jupiter. The remarkable filamentary structure in the Tvashtar plume is similar to details glimpsed faintly in 1979 Voyager images of a similar plume produced by Io's volcano Pele. However, no previous image by any spacecraft has shown these mysterious structures so clearly.
The image also shows the much smaller symmetrical fountain of the plume, about 60 kilometers (or 40 miles) high, from the Prometheus volcano in the 9 o'clock direction. The top of a third volcanic plume, from the volcano Masubi, erupts high enough to catch the setting Sun on the night side near the bottom of the image, appearing as an irregular bright patch against Io's Jupiter-lit surface. Several Everest-sized mountains are highlighted by the setting Sun along the terminator, the line between day and night.
This is the last of a handful of LORRI images that New Horizons is sending "home" during its busy close encounter with Jupiter - hundreds of images and other data are being taken and stored onboard. The rest of the images will be returned to Earth over the coming weeks and months as the spacecraft speeds along to Pluto.
Mar 05, 2007
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Jupiter_s_Aurorae.jpgJovian Aurorae54 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.MareKromiumMar 02, 2007
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