|
|
016-1-Ceres-Occator-Black_Shadow-01.jpgDark "Spot" inside Occator Crater (CTX Frame)118 visiteMareKromium
|
|
017-1-Ceres-Occator-Black_Shadow-02.jpgDark "Spot" inside Occator Crater (EDM)135 visiteMareKromium
|
|
018-1-Ceres-PIA22764.jpgOccator Crater on the Limb...125 visitenessun commentoMareKromium
|
|
018-Vesta-6-PIA13428.jpgSome of the "Faces" of 4-Vesta, from Hubble Space Telescope97 visiteNASA's Hubble Space Telescope snapped these images of the Asteroid 4-Vesta in preparation for the Dawn Spacecraft's visit in 2011. Each of the 4 Hubble images captures views of Vesta during its 5,34-hour rotation period. Hubble's sharp "eye" can see features as small as about 40 Km (24,84 miles) across in these images. Vesta was 211 MKM (approx. 131 MMs) from Earth when Hubble made the observations.
The images show the difference in brightness and color on the Asteroid's Surface. These characteristics hint at the large-scale features that the Dawn Spacecraft will see when it visits the potato-shaped asteroid.
Astronomers used the images, taken with Hubble's Wide Field Camera 3, to better determine 4-Vesta's Spin Axis. Based on the HST observations, astronomers calculated a slightly different, and more precise, Rotation Axis for Vesta. The new calculation will change the pattern of sunlight expected to illuminate the Asteroid when Dawn arrives.
Determining a more accurate Spin Axis for 4-Vesta will also help scientists refine the Dawn Spacecraft's orbit around the Asteroid. Dawn will orbit the rocky object for a year, beginning in July 2011. The Spacecraft will then travel to the "Dwarf Planet" 1-Ceres, arriving in 2015.
Hubble has kept its "eye" on 4-Vesta for more than 15 years, beginning in 1994. Hubble images of 4-Vesta in 1997 helped astronomers discover the Asteroid's very large Impact crater. Astronomers combined views of 4-Vesta in Near-UltraViolet and blue light to construct these images and the images were taken on Feb. 25, 2010.MareKromium
|
|
019-Vesta-5-PIA13427.jpg4-Vesta from Hubble Space Telescope104 visiteThe Asteroid 4-Vesta is somewhat like our Moon, with ancient Lava Beds (the dark patches) and powdery Debris (or Regolith), such as the pulverized remains of impacts (the orange-colored areas). A flattened area on one end of 4-Vesta is a giant Impact Crater formed by a collision that perhaps occurred billions of years ago.
The crater is approx. 460 Km (285,66 miles) across, which makes it close to 4-Vesta's roughly 530-Km (329,13-mile) diameter. The asteroid is about the size of Arizona.
4-Vesta is one of the largest of a reservoir of about 100.000 Asteroids, the leftover material from the formation of our Solar System.
Astronomers combined images of Vesta in Near-UltraViolet and blue light to make this picture movie. The Hubble observations were made on Feb. 25 and Feb. 28, 2010.MareKromium
|
|
020-1-Ceres-PIA22641.jpgUnusually-looking Surface Feature on 1-Ceres108 visiteCaption NASA Originale:"This image was obtained by NASA's Dawn Spacecraft on July 17, 2018 from an altitude of about 25 miles (such as approx. 40,23 Km).
The center of this picture is located at about 31,0° South Latitude and 248,9° East Longitude".MareKromium
|
|
021-1-Ceres-Cerealia_Facula-Occator_Crater-PIA21924.jpgCerealia Facula111 visiteCaption NASA Originale"This mosaic of Cerealia Facula is based on images obtained by NASA's Dawn Spacecraft in its second extended mission, from an altitude as low as about 21 miles (such as approx. 33,79 Km). The contrast in resolution obtained by the two phases is visible here, reflected by a few gaps in the high-resolution coverage. This image is superposed to a similar scene acquired in the low-altitude mapping orbit of the mission from an altitude of about 240 miles (i.e. approx. 386,24 km).
The increased resolution afforded by the low altitude is revealing intimate details about the relationships between bright and dark materials across the Facula (---> Bright Spot), which will help resolve the mystery of its origin.
Cerealia Facula is located at about 19,7° North Latitude and 239,6° East Longitude".MareKromium
|
|
021-Vesta-2.jpg4-Vesta, from HST55 visiteHubble observation of Vesta: picture taken with the Wide Field Planetary Camera 2 on May 14 and 16, 2007.
MareKromium
|
|
021-Vesta-3.jpgMoments of 4-Vesta55 visiteTo prepare for the Dawn spacecraft's visit to Vesta, astronomers used Hubble's Wide Field Planetary Camera 2 to snap new images of the asteroid. These images were taken on May 14 and 16, 2007. Each frame shows time in hours and minutes based on Vesta's 5,34-hour rotation period. Using Hubble, astronomers mapped Vesta's Southern Hemisphere, a Region dominated by a giant impact crater formed by a collision billions of years ago. The crater is 285 miles (456 Km) across, which is nearly equal to Vesta's 330-mile (530-Km) diameter.
Hubble's sharp "eye" can see features as small as about 37 miles (60 Km) across. The images show the difference in brightness and color on the asteroid's surface. These characteristics hint at the large-scale features that the Dawn spacecraft will see when it arrives at Vesta in 2011.
Hubble's view reveals extensive global features stretching longitudinally from the Northern Hemisphere to the Southern Hemisphere.
The images also show widespread differences in brightness in the east and west, which probably reflects compositional changes. Both of these characteristics could reveal volcanic activity throughout Vesta. The size of these different regions varies. Some are hundreds of miles across.
The brightness differences could be similar to the effect seen on the Moon, where smooth, dark regions are more iron-rich than the brighter highlands that contain minerals richer in calcium and aluminum. When Vesta was forming 4.5 billion years ago, it was heated to the melting temperatures of rock. This heating allowed heavier material to sink to Vesta's center and lighter minerals to rise to the surface.
Astronomers combined images of Vesta in two colors to study the variations in iron-bearing minerals. From these minerals, they hope to learn more about Vesta's surface structure and composition. Astronomers expect that Dawn will provide rich details about the asteroid's surface and interior structure.
MareKromium
|
|
022-Vesta-4.jpg4-Vesta (computer generated imaging - credits: Ben Zellner - Georgia Southern University -, Peter Thomas - Cornell University - and NASA)80 visiteUn'immagine decisamente bella, precisa, distinta. Ma è un'immagine "vera"? NO! Questa immagine dell'Asteroide 4-Vesta è "computer generated", così come sono "computer generated" TUTTE LE IMMAGINI CHE RITRAGGONO - IN CHIAVE PROSPETTICA - DELLE SEZIONI ISOLATE DELLA SUPERFICIE DI MARTE E CHE SONO STATE OTTENUTE DALLA SONDA ESA "MARS EXPRESS".
La differenza?
La differenza è nella "qualità" dell'immagine "computer generated": le immagini ESA sono - e lo ripeteremo sino alla nausea - alquanto dozzinali (Voi sapete che la pixellatura dei frames ESA ottenuti con questa tecnica è talmente grezza che, alla fine dell'opera, gli image-artifacts che li caratterizzano sono così tanti che, come è già accaduto tantissime volte, le sviste e le traveggole che essi ingenerano e suggeriscono sono davvero allucinanti); le immagini NASA, invece, sono di gran lunga più "smooth" (lisce, nel senso di prive di difettosità palesi ed artifacts) e, globalmente parlando, di fattura enormemente superiore.
Ma in ENTRAMBI I CASI SI TRATTA DI PSEUDO-IMMAGINI! Non lo dimenticate...
Caption NASA:"A 3-D computer model of the asteroid Vesta synthesized from Hubble topographic data. The crater's 8-mile high central peak can clearly be seen near the pole. The surface texture on the model is artificial, and is not representative of the true brightness variations on the asteroid. Elevation features have not been exaggerated". MareKromium
|
|
024-Vesta.jpg4-Vesta56 visite4-Vesta (o anche solo Vesta) è uno dei tanti asteroidi conosciuti da tantissimo tempo e che sembra, di quando in quando, avvicinarsi (in senso cosmico...) in maniera "perigliosa" al nostro pianeta.
Ma lo sanno tutti - gli Scienziati per primi - che, un giorno o l'altro, da oggi a fra qualche milione di anni nel futuro, qualche "roccia vagante" finirà con l'incrociare la sua orbita con quella della Terra e, quindi, con il produrre - con ogni probabilità - una catastrofe di dimensioni globali la quale sarà causa di sostanziali cambiamenti dell'intero ecosistema.
E' inevitabile, si sa.
Così come si sa che, quando questo momento arriverà, gli ultimi a prenderne atto saranno proprio quelli che, questo Pianeta, lo abitano...
|
|
039-Vesta-PIA14121.jpgApproaching 4-Vesta80 visitenessun commentoMareKromium
|
|
| 55 immagini su 5 pagina(e) |
2 |  |
|
|
