| Risultati della ricerca nelle immagini - "Asteroids:" |
Asteroids-1992-CO.jpgAsteroid 1992 CO58 visitenessun commento
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Asteroids-Annefrank_Asteroid-PIA02885_modest.jpgAsteroid Annefrank from Stardust64 visiteAsteroid Annefrank is seen as irregularly shaped, cratered body in an image taken by NASA's Stardust spacecraft during a Nov. 2 flyby of the asteroid.
Stardust flew within about 3.300 Km (about 2.050 miles) of the asteroid as a rehearsal for the spacecraft's encounter with its primary target, comet Wild 2, in January 2004. The camera's resolution was sufficient to show that Annefrank is about 8 Km (5 miles) in length, twice the predicted size from Earth-based observations. The surface reflects about 0,1 to 0,2% of sunlight, slightly less than anticipated. A few craters that are hundreds of meters across can be seen. The straight edge in the right side of the image may be an artifact of processing.
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Asteroids-Hygiea.jpgAsteroid 10 Hygiea78 visiteGrazie al lavoro della "Two Micron All Sky Survey - 2MASS" siamo in grado di offrirvi le immagini di qualche asteroide del tutto sconosciuto (crediamo) a coloro che non siano - in qualche modo - direttamente "addetti ai lavori" nei Campi dell'Astronomia e/o dell'Astrofisica (Studenti delle due Discipline inclusi).
Si tratta di immagini che non ci dicono molto, dal punto di vista di un eventuale studio delle caratteristiche superficiali di questi oggetti (a dire il vero una cosa sembrano dirla: si tratta di oggetti davvero molto luminosi!), ma che, in ogni caso, rimangono molto suggestive e sono capaci di mostrarci dei "frammenti" di Cielo che contengono, oltre ai cosiddetti "corpi fissi" (cioè stelle e galassie), anche degli oggetti "mutevoli e transitori" (almeno dal punto di vista di chi li osserva).
Gli Asteroidi, appunto.
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Asteroids-Pallas.jpgAsteroid 2 Pallas54 visitenessun commento
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DACTYL-PIA00297.jpgAsteroid Dactyl59 visiteThis image is the most detailed picture of the recently discovered natural satellite of asteroid 243 Ida taken by the Galileo Solid-State Imaging camera during its encounter with the asteroid on August 28, 1993. Shuttered through the camera's broadband clear filter as part of a 30-frame mosaic designed to image the asteroid itself, this frame fortuitously captured the previously unknown moon at a range of about 3,900 kilometers (2,400 miles), just over 4 minutes before the spacecraft's closest approach to Ida. Each picture element spans about 39 meters (125 feet) on the surface of the moon. More than a dozen craters larger than 80 meters (250 feet) in diameter are clearly evident, indicating that the moon has suffered numerous collisions from smaller Solar System debris during its history. The larger crater on the terminator is about 300 meters (1,000 feet) across.
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DACTYL-PIA00298.jpgAsteroid Dactyl57 visiteWithin seconds of its closest approach to the asteroid 243 Ida on August 28, 1993, the Galileo spacecraft's Solid State Imaging camera caught this glimpse of Ida's previously unknown moon orbiting the asteroid. One frame of a 15-image set designed to capture a view of Ida at the highest possible resolution landed by chance with its edge right on the little moon. The range from the spacecraft was about 2.400 Km and each picture element spans about 24 meters (80 feet) on the surface of the moon. Only a small sliver of the sunlit crescent is visible at the edge of the frame (which was shifted inward toward the center in this frame). Dactyl is approximately egg-shaped, measuring about 1.2 x 1.4 x 1.6 Km (0.75 x 0.87 x 1 mile). At the time this image was shuttered, Ida was about 90 Km (56 miles) away from the moon, outside this frame to the left and slightly below center. The smoothly curving shape of the dark edge of Ida's moon can be seen on the left. The moon's observed darkside was just barely detectable.
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EROS-G-TouchDown.jpg433 Eros: 4 years after the "touch-down"!57 visiteCaption da "NASA - Picture of the Day" del 12.02.2005:"On 12 February, 2001, the NEAR-Shoemaker spacecraft gently touched-down on the the surface of Eros - the first ever landing on an asteroid. During the descent, the spacecraft's camera recorded successive images of the diminutive world's surface, revealing fractured boulders, dust filled craters, and a mysterious collapsed channel. The last frame, seen in the above montage at the far left, was taken at a range of 128 meters. Expanded in the inset, it shows surface features a few centimeters across. Stereo experimenter Patrick Vantuyne, constructed this montage from the final images in the landing sequence, carefully identifying the overlapping areas in successive frames. Frames which overlap were taken by the spacecraft from slightly different viewpoints, allowing Vantuyne to construct close-up stereo images of the surface of asteroid 433 Eros".
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EROS-PIA02492.jpgEros in true colors85 visiteAs the NEAR Shoemaker spacecraft descends into lower orbits around Eros, it continually returns higher spatial resolution images of the asteroid. The true color image at left was taken February 12, 2000, from a range of 1.748 Km and shows details only as small as 180 meters (590 feet) across. It was taken two days before orbit insertion, as part of an image sequence designed to provide moderate-resolution color mapping of Eros at a near-constant viewing geometry. The true color image inset at right was taken February 29 from a range of 283 Km and shows much smaller details only 27 meters (89 feet) across.
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EROS-PIA02493_modest.jpgSunset on Eros55 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)138 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-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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