| Piú viste |
The Rings-PIA08288.jpgSpokes!55 visiteA group of bright spokes tightly cluster together in Saturn's B ring. The spokes seen here generally all exhibit the same degree of shearing, or tilting, but some deviations are apparent. In this image, the direction to Saturn is downward; orbital motion is to the left.
Ring scientists are eager for data to help them understand and eventually explain how these mysterious ring features are created. To that end, Cassini has been directed to acquire movie sequences, like the one this image is part of, that watch for these elusive radial structures.
This observation focused on the morning side of the rings, the side where the rings are rotating out from Saturn's shadow. Spokes appear most frequently at this location.
Also barely visible in this image are broader, much fainter but still bright radial regions that extend over larger radial distances than the spokes in the upper left. Where these fainter features cross ringlets in the lower part of the image, slight variations in brightness are apparent. These are probably due to tiny particles, possibly part of a former spoke, that haven't yet settled down onto the ring plane.
Although their formation is still a subject of inquiry, scientists are confident that the microscopic spoke particles are slightly electrically charged and therefore are influenced by Saturn's magnetic field.
The brightness of the spokes, when combined with viewing geometry information and estimates of their particle sizes can help researchers determine the amount of material in the spokes--a crucial quantity to constrain theories of spoke formation.
The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Sept. 28, 2006, at a distance of approximately 1.3 million kilometers (800,000 miles) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 147 degrees. Scale in the original image was about 32 kilometers (20 miles) per pixel. The view has been magnified by a factor of two.
|
|
OPP-SOL959-1N213321927EFF76POP0663R0M1.jpgShall we get in?... (2) - Sol 95955 visitenessun commento
|
|
OPP-SOL959-1N213321978EFF76POP0663L0M1.jpgShall we get in?... (2) - Sol 95955 visitenessun commento
|
|
OPP-SOL959-1N213322030EFF76POP0663R0M1.jpgShall we get in?... (3) - Sol 95955 visitenessun commento
|
|
OPP-SOL952-PIA08809-1.jpgCape Verde (1)55 visiteCaption NASA originale:"This view of Victoria Crater is looking North from Duck Bay towards the dramatic promontory called Cape Verde. The dramatic cliff of layered rocks is about 50 mt (about 165 feet) away from the Rover and is about 6 mt (about 20 feet) tall. The taller promontory beyond that is about 100 mt (about 325 feet) away, and the vista beyond that extends away for more than 400 mt (about 1300 feet) into the distance. This is an approximately true color rendering of images taken by the PanCam on NASA's Mars Exploration Rover Opportunity during the rover's 952nd Sol (Sept. 28, 2006) using the camera's 750-nanometer, 530-nanometer and 430-nanometer filters".
|
|
OPP-SOL952-PIA08807-1.jpgCabo Frio (1)55 visiteCaption NASA originale:"This view of Victoria Crater is looking South-East from Duck Bay towards the dramatic promontory called Cabo Frio. The small crater in the right foreground, informally known as Sputnik, is about 20 mt (about 65 feet) away from the Rover, the tip of the spectacular, layered, Cabo Frio promontory itself is about 200 mt (about 650 feet) away from the Rover, and the exposed rock layers are about 15 mt (about 50 feet) tall. This is an approximately true color rendering of images taken by the PanCam on NASA's Mars Exploration Rover Opportunity during the rover's 952nd Sol (Sept. 28, 2006) using the camera's 750-nanometer, 530-nanometer and 430-nanometer filters".
|
|
OPP-SOL952-PIA08807-2.jpgCabo Frio (2)55 visitenessun commento
|
|
The Rings-PIA01940.jpgInfrared Rings55 visiteThis mosaic of Saturn's rings was acquired by Cassini's VIMS (Visual and Infrared Mapping Spectrometer) on Sept. 15, 2006, while the spacecraft was in the shadow of the Planet looking back towards the Rings from a distance of about 2,16 MKM (approx. 1,34 MMs).
Data at wavelengths of 1,0, 1,75 and 3,6 microns were combined in the blue, green and red channels to make the pseudo-color image shown here. The brightest feature in the mosaic is the F-Ring, located at the outer edge of the main Rings. The F-Ring is overexposed and appears white in this image. Of the main A, B and C Rings; the C-Ring is the most prominent and reddish in color, becoming saturated close to the Sun. The more opaque A and B Rings are muddy in color and very dark in this geometry.
By contrast, the normally faint D-Ring, located just interior to the C-Ring, is quite bright and blue, indicating the presence of very small ring particles. Similarly, a narrow, green ringlet in the Cassini Division, as well as the greenish G-Ring and blue E-Ring - located at increasing distances outside the F-Ring - are predominantly composed of small particles.
The faint reddish band immediately outside the F-Ring is likely to be an artifact caused by the extremely bright F-Ring.
|
|
Phoebe-PIA06401.jpgFrozen water on Phoebe55 visiteCaption NASA originale:"On the right, the ultraviolet image of Saturn's moon Phoebe, taken from a distance of approx. 31.000 Km (such as about 19.263 miles) shows an irregular surface and bright crater region (white area). The bright areas indicate water frost on Phoebe's surface.
The image was taken by Cassini's UltraViolet Imaging Spectrograph during the spacecraft's closest approach to Phoebe, on June 11, 2004.
The large crater shows clearly in the image on the left".
|
|
Enceladus-PIA08286.jpgCrescent Enceladus55 visiteCaption NASA originale:"A world whose mysteries are just coming to light, Enceladus has enchanted scientists and non-scientists alike. With its potential for near-surface liquid water, the icy moon may be the latest addition to the list of possible abodes for life (!).
The view was acquired about two-and-a-half hours after PIA08280, during one of the many encounters with Enceladus.
The image was taken using a combination of spectral filters sensitive to wavelengths of polarized ultraviolet light. The Cassini spacecraft narrow-angle camera acquired the view on Sept. 9, 2006 at a distance of approx. 141.000 Km (about 87.000 miles) from Enceladus and at a Sun-Enceladus-spacecraft, or phase, angle of 96°.
Image scale is roughly 850 mt (about 0,5 mile) per pixel".
|
|
The Rings-PIA08285.jpgNot the Sun, but Aldebaran!55 visitenessun commento
|
|
The Rings-PIA08287.jpgNot the Sun, but Aldebaran!55 visiteCaption NASA originale:"Cassini took a series of images on Sept. 9, 2006 as it watched the bright red giant star Aldebaran slip behind Saturn's Rings.
This type of observation is known as a "stellar occultation" and uses a star whose brightness is well known. As Cassini watches the rings pass in front, the star's light fluctuates, providing information about the concentrations of ring particles within the various radial features in the Rings.
Here, Cassini watches the star through the part of the Rings masked by Saturn's shadow. The view looks toward the sunlit side of the Rings from about 20° below the Ring-Plane. Bright Aldebaran is over exposed, creating thin vertical lines ("effetto goccia") on its image.
The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Sept. 9, 2006 at a distance of approx. 351.000 Km (such as about 218.000 miles) from Saturn. Image scale on the sky at the distance of Saturn is 2 Km (a little more than 1 mile) per pixel".
|
|
| 25353 immagini su 2113 pagina(e) |
 |
|
|
|
|
2042 | |
|
|
|
|
