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EROS-PIA02493_modest.jpgSunset on Eros53 visiteEros' irregular shape gives rise to some stunning vistas at the time of sunrise or sunset. On March 6, 2000, the imager on the NEAR Shoemaker spacecraft caught this view of a stunning sunset. In the pitch black foreground the Sun has already set, but just over the horizon another part of the asteroid remains lit. Eros' rotation period is just 5 hours, 16 minutes, so in the course one 24-hour Earth day an observer on Eros would be treated to four full cycles of sunrises and sunsets.
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EROS-PIA02901_modest.jpgCraters on the limb of Eros55 visiteIn this image, taken April 17, 2000, from a height of 101 Km (63 miles), the shadows highlight small-scale surface features. The surface is pockmarked with craters ranging in size up to the 2,8 Km (1,74 mile) diameter crater in the center of the image. The smallest craters which can be resolved are about 20 meters (65 feet) across. In lower right corner of the image, 20-meter boulders can be seen that were not evident in images from higher altitudes.
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EROS-PIA02905-0.jpgEros (the BIG Pseudo-Anomaly)135 visiteThis image of Eros, taken from the NEAR Shoemaker spacecraft on May 1, 2000, is among the first to be returned from "low orbit." Between May and August, the spacecraft orbited at altitudes near 50 Km or less. This will be the prime period of activity for some of the spacecraft's science instruments. The X-ray / gamma-ray spectrometer will build up maps of chemical abundances, while the laser rangefinder measures the shape of Eros to within meters (a few feet). At the same time the magnetometer will watch for indications of Eros' magnetic field and the near-infrared spectrometer will map rock types. The imager will take pictures of the entire surface of Eros that capture features as small as 4 meters (13 feet) across. This particular image, taken from an orbital altitude of 53 Km, shows a scene about 1.8 Km across. Numerous craters and boulders as small as 8 meters (26 feet) across dot the landscape. The large, rectangular boulder at the upper right is about 45 meters across.
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EROS-PIA02905-1.jpgEros (Position of the BIG Pseudo-Anomaly)53 visitenessun commentoMareKromium
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EROS-PIA02906_modest.jpgHorizon view56 visiteThis image of Eros, taken from the NEAR Shoemaker spacecraft on May 2, 2000, from an orbital altitude of 52 kilometers (32 miles), shows a view toward Eros' horizon. The section shown is about 1.8 kilometers (1.1 miles) across. This particular view provides a snapshot of three of the most common types of features seen on the asteroid: craters whose rims have been rounded by erosion due to smaller impacts and blanketing by the impact debris, or regolith (impact debris); variations in the brightness of material on the walls of the craters; and a scattering of boulders ranging in size from nearly 100 meters (328 feet) down to about 8 meters (26 feet).
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EROS-PIA02907_modest.jpgA strange drawing made by lights and shadows...56 visiteEros' irregular shape creates interesting and beautiful scenes where the Sun shines obliquely on the surface. In the absence of an atmosphere, and hence no secondary illumination reflecting from atmospheric molecules, shade appears nearly as black as space. This image, taken from the NEAR Shoemaker spacecraft on May 2, 2000, from an orbital altitude of 50 kilometers (31 miles), shows one of the more telling and yet comical combinations of light and shadow. The entire scene is about 1.8 kilometers (1.1 miles) across. High spots near the edges of shadows, like the 35-meter (115-foot) diameter boulder just below the center of the frame, seem almost to "float" above the surface. With a little imagination, the shadow dominating the right side of the frame could be seen as a small, long-eared terrier bending over to sniff his dinner!
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EROS-PIA02927.jpgEros' Boulders121 visiteNEAR Shoemaker images have shown many large boulders on Eros' surface, but seldom are the boulders as big and as close as the ones in this image taken on June 20, 2000, from an altitude of 51 Km. Nestled within the 700-meter (2300-foot) diameter crater at the center of the picture are four particularly large rocks whose tops protrude out from the shadowed crater interior and into sunlight. The center boulder, the largest, is about 100 meters (330 feet) across. The whole scene is approximately 1.9 Km across.
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EROS-PIA02951.jpgEros from above (1)57 visiteIn NEAR Shoemaker's long-awaited close-up images of Eros, the asteroid's small-scale features are revealing their fascinating diversity. This picture, taken July 8, 2000, from an orbital altitude of only 36 Km, shows a variety of differently shaped boulders. Some are nearly round, whereas others are elongated or even blade-shaped. Such varied shapes might arise from differences in the strength and fracturing of preexisting rock. The whole scene is about 1.4 Km across.
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EROS-PIA03129.jpgEros from above (2)63 visiteNEAR Shoemaker photographed this area of Eros on December 18, 2000, from an orbital altitude of 33 Km. This part of the asteroid's surface, like many others, appears vaguely "sculptured" due to its low, elongated ridges and depressions with seemingly consistent orientations. Some of the low spots also contain accumulations of smooth, pond-like materials. Neither the surface sculpturing nor the pond-like materials are well understood, and both will be investigated in detail using even higher-resolution images from NEAR Shoemaker's low passes over Eros in early 2001. The whole scene is about 1 Km across.
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EROS-PIA03143.jpgEros: NEAR-Shoemaker's Probe landing site75 visiteThe location of NEAR Shoemaker's landing site is shown in this image mosaic taken on December 3, 2000, from an orbital altitude of about 200 Km (approx. 124 miles). In this view, south is to the top and the terminator (the imaginary line dividing day from night) lies near the equator. The landing site (at the tip of the arrow) is near the boundary of two distinctly different provinces, both of which the spacecraft will photograph as it descends. To the south and east (above and to the left) lies older, cratered terrain, while to the north (down) is the saddle-shaped feature Himeros, whose lesser density of superposed craters indicates relatively recent resurfacing by geologic processes.
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EnckeCometTailRipoff_movie_short.gifComet Encke encounters a CME54 visiteCaption NASA:"Swinging inside the orbit of Mercury, on April 20th, 2007, periodic comet Encke encountered a blast from the Sun in the form of a Coronal Mass Ejection (CME). When CMEs, enormous clouds of energetic particles ejected from the Sun, slam into Earth's magnetosphere, they often trigger auroral displays.
But in this case, the collison carried the tail of the comet away.
The tail was likely ripped off by interacting magnetic fields rather than the mechanical pressure of the collision.
This a GIF-movie showing the remarkable event as recorded by the Heliospheric Imager onboard the STEREO A spacecraft. In the movie, the time between frames is about 45 minutes, while the frames span about 14x20 MKM at the distance of the comet. Of course, similar collisions have happened before as the ancient comet loops through its 3,3 year solar orbit. So don't worry, Encke's tail will grow back!".MareKromium
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Eris.jpgAnother "Dwarf Planet" with satellite: 136199-Eris and Dysnomia53 visiteDa "NASA - Picture of the Day" del 18 Settembre 2006:"Is Pluto the largest Dwarf Planet? No! Currently, the largest known dwarf planet is 136199-Eris, renamed last week from 2003 UB313. Eris is just slightly larger than Pluto, but orbits as far as twice Pluto's distance from the Sun. Eris is shown above in an image taken by a 10-meter Keck Telescope from Hawaii, USA.
Like Pluto, Eris has a moon, which has been officially named by the International Astronomical Union as (136199) Eris I (Dysnomia). Dysnomia is visible above just to the right of Eris. Dwarf Planets Pluto and Eris are Trans-Neptunian Objects that orbit in the Kuiper belt of objects past Neptune. Eris was discovered in 2003, and is likely composed of frozen water-ice and methane. Since Pluto's recent demotion by the IAU from planet to dwarf planet status, Pluto has recently also been given a new numeric designation: 134340-Pluto.
Currently, the only other officially designated Dwarf Planet is 1-Ceres".
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