| Piú votate - Asteroids and Comets |
Comets-Borrelly_Comet-PIA03500_modest.jpgThe "Borrelly" Comet from Deep Space 154 visiteIn this highest resolution view of the icy, rocky nucleus of comet Borrelly, (about 45 meters or 150 feet per pixel) a variety of terrains and surface textures, mountains and fault structures, and darkened material are visible over the nucleus's surface. This was the final image of the nucleus of comet Borrelly, taken just 160 seconds before Deep Space1's closest approach to it. This image shows the 8-km (5-mile) long nucleus about 3417 kilometers (over 2,000 miles) away.
Smooth, rolling plains containing brighter regions are present in the middle of the nucleus and seem to be the source of dust jets seen in the coma. The rugged land found at both ends of the nucleus has many high ridges along the jagged line between day and night on the comet. This rough terrain contains very dark patches that appear to be elevated compared to surrounding areas. In some places the dark material accentuates grooves and apparent faults.
(13 voti)
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Xena.jpgXena: another "Tenth Planet"? (2003 UB313)55 visiteNASA's Hubble Space Telescope has resolved the Tenth Planet, now nicknamed Xena, for the first time and has found that it is only just a little larger than Pluto.
Though previous ground-based observations suggested that Xena was about 30% greater in diameter than Pluto, Hubble observations taken on Dec. 9 and 10, 2005, yield a diameter of 1.490 miles (with an uncertainty of 60 miles) for Xena. Pluto's diameter, as measured by Hubble, is 1.422 miles. Xena is the large object at the bottom of this artist's concept. A portion of its surface is lit by the Sun, located in the upper left corner of the image. Xena's companion, Gabrielle, is located just above and to the left of Xena.
(8 voti)
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Asteroids-Annefrank_Asteroid-PIA02885_modest.jpgAsteroid Annefrank from Stardust63 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.
(15 voti)
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DACTYL-PIA00297.jpgAsteroid Dactyl52 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.
(6 voti)
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Comets-Comet_Ikeya_Zhang_2.jpgComet Ikeya-Zhang (from Colorado)60 visiteThis lovely early evening view of the comet in Rocky Mountain skies looks northwest over ridges and low clouds. The time exposure was recorded on March 31st from an 8.000 foot elevation near Yampa, Colorado, USA. Sporting a sweeping yellowish dust tail and blue ion tail eight to ten degrees long, Ikeya-Zhang is nestled near the horizon in the northern constellation of Andromeda. To the comet's left is the bright star Mirach or Beta Andromedae while the stretched celestial fuzzball to the comet's right is M 31 or the Andromeda galaxy, the nearest bright spiral galaxy to our own Milky Way. As the days pass, Comet Ikeya-Zhang's apparent motion through the sky is towards the right in this image. Tonight, comet-watchers blessed with clear skies should find Ikeya-Zhang posing perfectly for binoculars and cameras just above M 31, less than two degrees from the center of the bright galaxy.
(16 voti)
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Tempel 1-PIA07879.jpgComet "Tempel 1"54 visiteCaption NASA originale:"Sixty-nine days before it gets up-close-and-personal with a comet, NASA's Deep Impact spacecraft successfully photographed its quarry, comet Tempel 1, at a distance of 39,7 MMs. The image, taken on April 25, 2005, is the first of many comet portraits Deep Impact will take leading up to its historic comet encounter on July 4, 2005".
(5 voti)
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DACTYL-PIA00298.jpgAsteroid Dactyl53 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.
(8 voti)
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Tempel1-q.jpg13 MKM from Comet Tempel 153 visiteDa "NASA - Picture of the Day" del 29 Giugno 2005:"The Deep Impact spacecraft continues to close on Comet Tempel 1, a comet roughly the size of Manhattan. Early on July 3 (EDT), the Deep Impact spacecraft will separate in to 2 individual robotic spaceships, one called Flyby and the other called Impactor. During the next 24 hours, both Flyby and Impactor will fire rockets and undergo complex maneuvers in preparation for Impactor's planned collision with Comet Tempel 1. On July 4 (1:52 am EDT) if everything goes as scheduled, the 370-Kg Impactor will strike Tempel 1's surface at over 14.000 Km p.h.. Impactor will attempt to photograph the oncoming comet right up to the time of collision, while Flyby photographs the result from nearby. The above image was taken on 19 June from about 13 MKM out and used to help identify the central nucleus of the comet inside the diffuse coma. Telescopes around the Earth, including the HST, will also be closely watching the distant silent space bullet".
(4 voti)
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Asteroids-Opportunity-041007163946.jpgThe path to immortality: an asteroid named "Opportunity"54 visiteL'immortalità (o quasi), in qualche modo, le Sonde Spirit ed Opportunity sono riuscite a guadagnarsela: il lavoro svolto dai due Rover, infatti, è stato (ed è tuttora) così prezioso e scientificamente significativo che si è pensato - ed è la prima volta in assoluto che accade una cosa simile - di dedicare ai due robot (e NON, quindi, ad un "essere umano"...) due asteroidi scoperti all'inizio degli anni '60, ma definitivamente riconosciuti e codificati - mediante l'assegnazione di un numero seriale ufficiale - solo nel 2002 (in questo caso, però, non si è trattato di inefficienza, bensì di ottemperanza alle rigide regole stabilite dalla IAU - International Astronomical Union - le quali "...require asteroids to be observed during 4 separate cycles around the Earth and Sun before they become eligible for numbering and naming...").
(19 voti)
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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.
(18 voti)
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Asteroids-1992-CO.jpgAsteroid 1992 CO57 visitenessun commento
(17 voti)
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Asteroids-Pallas.jpgAsteroid 2 Pallas54 visitenessun commento
(17 voti)
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