| Piú votate - SOLAR SYSTEM |
EnceladusFountains-PIA07762.gifThe "Fountains" of Enceladus133 visiteJets of icy particles burst from Enceladus in this GIF sequence of 4 images taken on Nov. 27, 2005. The sensational discovery of active eruptions on a third outer Solar System body (after Jupiter's moon, Io, and Neptune's moon, Triton) is one of the great highlights of the Cassini mission.
Images taken in January 2005, appeared to show the plume originating from the fractured South Polar Region of Enceladus, but the visible plume was only slightly brighter than the background noise in the image because the lighting geometry was not suitable to reveal the true details of the feature. This potential sighting, in addition to the detection of the icy particles in the plume by other Cassini instruments, prompted imaging scientists to target Enceladus again with exposures designed to confirm the validity of the earlier plume sighting.
The new views show individual jets, or plume sources, that contribute to the plume with much greater visibility than the earlier images.
The full plume towers over the 505-kilometer-wide (314-mile) moon, and is at least as tall as the moon's diameter.
The four, 10-second exposures were taken over the course of about 36 minutes at approximately 12-minute intervals. Enceladus rotates about 7.5 degrees in longitude over the course of the frames, and most of the observed changes in the appearances of the jets are likely due to changes in the viewing geometry. However, some of the changes may be due to actual variation in the flow from the jets on a time scale of tens of minutes.
Additionally, the shift of the sources seen here should provide information about their location in front of and behind the visible limb (edge) of Enceladus.
These images were obtained using the Cassini spacecraft narrow-angle camera at distances between 144,350 and 149,520 kilometers (89,695 and 92,907 miles) from Enceladus and at a phase angle of about 161 degrees. Image scale is about 900 meters (2,950 feet) per pixel on Enceladus.
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Itokawa-06.jpgOrbiting around Itokawa (3)65 visiteSpecifically, at the time of arrival at Itokawa, Hayabusa had driven its proprietary new ion engines for 26.000 hours, including their operation during an Earth flyby.
It has also perfectly completed a period of hybrid optical navigation followed by
precise guidance and navigation of the spacecraft during its station keeping period around Itokawa.
These engineering achievements are the primary mission of Hayabusa and their successful completion is a great achievement.
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Itokawa-05.jpgOrbiting around Itokawa (2)70 visiteHayabusa is a technology demonstration spacecraft focusing on key technologies that are required for future large-scale sample and return missions, yet is also making new scientific observations and discoveries. The technology demonstration component of the mission consists of 5 goals:
1) ion engine propulsion in interplanetary cruise;
2) ion engine propulsion in combination with an Earth gravity assist;
3) autonomous guidance and navigation using optical measurements;
4) collection of surface samples in an ultra-low gravity environment and
5) the direct recovery of these samples on the ground after its return from interplanetary flight.
To date the Hayabusa project has accomplished these demonstrations up through
the third goal.
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Itokawa~0.jpgClosing on Itokawa64 visiteItokawa: un asteroide che sembra contraddire tutto quanto viene dato per acquisito nel campo delle forme esteriori e dei rilievi superficiali dei corpi (teoricamente) esposti a pesantissimi azioni di impatto sin dagli albori della loro esistenza. Pensate a 433-Eros, oppure a Ceres, o Dactyl o a qualsiasi altro corpo similare che abbiamo avuto occasione di vedere da distanza ravvicinata. Forse il solo asteroide AnneFrank non sembra presentare una particolare craterizzazione (ma le immagini, di cattiva qualità, non possono essere considerate definitorie) e quindi si viene a porre nel novero delle rarità. Tuttavia, quello che vediamo adesso, è ben più che un'eccezione e molto di più di un'Anomalìa: Itokawa NON ha alcun cratere superficiale visibile e le sue forme, spigolose ed a tratti aguzze, costituiscono una novità assoluta per i Ricercatori e gli Studiosi di Scienze Planetarie.
Original caption:"Where are the craters on asteroid Itokawa? No one knows. The Japanese robot probe Hayabusa recently approached the Earth-crossing asteroid and is returning pictures showing a surface unlike any other Solar System body yet photographed -- a surface possibly devoid of craters. One possibility for the lack of common circular indentations is that asteroid Itokawa is a rubble pile -- a bunch of rocks and ice chunks only loosely held together by a small amount of gravity. If so, craters might be filled in whenever the asteroid gets jiggled by a passing planet -- Earth in this case. Alternatively, surface particles may become electrically charged by the Sun, levitate in the microgravity field, and move to fill in craters. Over the weekend, Hayabusa lowered itself to the surface of the strange asteroid in an effort to study the unusual body and collect surface samples that could be returned to Earth in 2007".
(10 voti)
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Calypso-PIA07633.jpgCalypso (in false colors)64 visiteThis color image provides the best look yet at Saturn's moon Calypso, a Trojan of the larger moon Tethys. Calypso trails Tethys in its orbit by 60°. Telesto is the other Tethys Trojan, orbiting Saturn 60°ahead of Tethys. Calypso is only 22 Km (about 14 miles) across. Calypso, like many other small Saturnian moons and small asteroids, is irregularly shaped by overlapping large craters. Although the resolution here is not as high as in Cassini's best images of Pandora and Telesto, this moon appears to also have loose surface material capable of smoothing the appearance of craters. (...) The images were taken with the Cassini spacecraft narrow-angle camera on Sept. 23, 2005, at a distance of approx. 101.000 Km (about 63.000 mi) from Calypso and at a phase angle of 61°. Resolution in the original image was 602 mt per pixel (...) ".
Nota: notiamo un'incredibile somiglianza fra Calypso e l'asteroide 433-Eros. Coincidenza, o c'è una sorta di "marchio di fabbrica" che unisce le piccole lune agli asteroidi?
(10 voti)
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Kuiper_s Belt.jpgRelationship of the Kuiper's Belt to the Oort's Cloud89 visiteThis illustration shows that the Kuiper Belt is shaped like a disk (see inset diagram) and resides within the shell-like structure of the Oort Cloud. Located on the outskirts of the Solar System, the Kuiper Belt is a "junkyard" of countless icy bodies left over from the Solar System's formation. The Oort Cloud is a vast shell of billions of comets.
The inset diagram compares Pluto's orbit with a Kuiper Belt binary object called 1998 WW31. The Kuiper Belt [the fuzzy disk] extends from inside Pluto's orbit to the edge of the Solar System.
(10 voti)
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ZU-2005-19-b-large_web.jpgPluto's System: the best images so far (2)61 visiteSemplifichiamo: la nostra speculazione dice che i due nuovi corpi (che chiameremo P1 e P2) NON orbitano attorno a Plutone in un rapporto riconducibile al modello classico "Satellite:Parent Planet", bensì costituiscono un Sistema Binario Indipendente il quale si trova in - semplice - equilibrio gravitazionale rispetto ad un altro Sistema Indipendente.
Le prove di una simile (azzardata, ma affascinante) costruzione, le potremmo trovare solo studiando in maniera ultra-dettagliata i movimenti di P1 e P2 rispetto a Plutone e Caronte. Movimenti che, se la nostra speculazione fosse corretta, configurerebbero percorsi orbitali - dal nostro punto di vista - "completamente anomali" e riassumibili in questo schema logico:
Plutone è Parent Planet di Caronte e SOLO di Caronte il quale gli orbita attorno assecondando un'orbita circolare; P1 e P2, invece, si muovono armonicamente l'uno rispetto all'altro e, nel farlo, "orbitano" (in senso ampio) attorno al Sistema Plutone-Caronte (che diventa "Parent System").
(10 voti)
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ZE-Pluto-fict-map.jpgFictional Map of Pluto95 visiteLa superficie di Plutone - così ben dettagliata - è frutto dell'immaginazione dell'Artista; altrettanto, invece, non si può dire del colore del paesaggio il quale - a quanto ci è stato detto - è coerente con quanto pensano gli Scienziati che hanno osservato e fotografato Plutone usando le spettacolari ottiche dell'HST, nonchè le tecniche di ripresa maggiormente efficaci ed all'avanguardia. Le stesse tecniche, guarda caso, che ci permettono di dire che la superficie della lontanissima Sedna è rossiccia, ma che non risultano adeguate a chiarire il mistero dei "colori" del vicino - in tutti i sensi - Marte.
Curioso, non credete?!?
(10 voti)
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Io-GalaiPatera-PIA00324.jpgGalai Patera63 visiteIo's volcanic plains are shown in this Voyager 1 image, which spans an area about 1030 km (640 miles) from left to right. North is about the 1:30 position. Numerous volcanic calderas and lava flows are visible here. The brown teardrop-shaped feature at left center is Galai Patera, a 100-km-long (62 mi) lava-flooded caldera (collapsed vent) of a volcano. The composition of Io's volcanic plains and lava flows has not been determined. The prevalent yellow, brown, and orange material may consist dominantly of sulfur with surface frosts of sulfur dioxide or of silicates (such as basalt) encrusted with sulfur and sulfur dioxide condensates. The whitish patches probably are freshly deposited SO2 frost.
(10 voti)
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Io-LokiPatera-PIA00320.jpgLoki patera: an everlasting eruption...67 visiteA huge area of Io's volcanic plains is shown in this Voyager 1 image mosaic. Numerous volcanic calderas and lava flows are visible here. Loki Patera, an active lava lake, is the large shield-shaped black feature. Heat emitted from Loki can be seen through telescopes all the way from Earth. These telescopic observations tell us that Loki has been active continuously (or at least every time astronomers have looked) since the Voyager 1 flyby in March 1979. The composition of Io's volcanic plains and lava flows has not been determined, but they could consist dominantly of Sulphur (S) with surface frosts of S dioxide or of silicates (such as basalts) encrusted with S and S dioxide condensates. The bright whitish patches probably consist of freshly deposited SO2 frost. The black spots, including Loki, are probably hot sulfur lava, which may remain molten by intrusions of molten silicate magma, coming up from deeper within Io. The ultimate source of heat that keeps Io active is tidal frictional heating due to the continual flexure of Io by the gravity of Jupiter and Europa, another of Jupiter's satellites.
(10 voti)
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Janus-N00041468.jpgJanus and Prometheus61 visiteN00041468.jpg was taken on October 13, 2005 and received on Earth October 14, 2005. The camera was pointing toward JANUS - distant approximately 876.959 Km away - and the image was taken using the CL1 and CL2 filters. This image has not been validated or calibrated.
(10 voti)
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ZZ-ZZ-Annular_seip_big.jpgThe "Annular Eclipse" of October, 3rd, 2005 (HR)66 visiteDa "NASA - Picture of the Day" del 5 Ottobre 2005:"On Monday, part of the Sun went missing. The missing piece was no cause for concern because the Moon was only momentarily in the way. The event was not a total eclipse of the Sun for any Earth-bound sky enthusiast but rather, at best, an annular eclipse, where the Moon blocked most of the Sun. Because of the relatively large distance to the Moon during this Earth-Moon-Sun alignment, the Moon did not have a large enough angular size to block the entire Sun. Those who witnessed the solar eclipse from a narrow path through Spain and Africa, however, were lucky enough to see the coveted Ring of Fire, a dark Moon completely surrounded by the brilliant light of the distant Sun. Pictured above is a Ring of Fire captured two days ago in unusually HR above Spain. The resulting image shows details of the granular solar surface as well as many prominences around the Sun".
(10 voti)
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