Saturn: the "Ringed Beauty" and His Moons
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Aldebaran-PIA08300.jpgThrough the B-Ring82 visiteThese side-by-side views of a star (Aldebaran?) seen through Saturn's densely populated B-Ring show marked contrast between the region where spokes - the ghostly radial features periodically seen in it - are produced and regions where no spokes are seen.
In the view at left, the B-Ring displays an uneven grainy texture, with a great deal of variability in brightness along the direction of the particle motion. In the view at right, the B-Ring is far smoother and more uniform along the same longitudinal direction.
Ring scientists on the Cassini Imaging Team are studying images such as these to understand the processes by which spokes are created. This difference in appearance from one location to another on the Ring could provide the researchers with helpful insights into the features' formation.
These views were acquired about half an hour apart as the Cassini spacecraft looked toward the unlit side of the Rings from about 33° above the Ring-Plane.
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Alpha_Centauri-PIA10406.jpgStellar Horizon (MULTISPECTRUM; credits: Lunexit)54 visiteCaption NASA:"The nearest Star System, the Trinary Star Alpha Centauri, hangs above the horizon of Saturn. Both Alpha Centauri A and B -- stars very similar to our own -- are clearly distinguishable in this image. (The third star in the Alpha Centauri System, the red dwarf Proxima Centauri, is not visible here).
From the orbit of Saturn, light (as well as Cassini's radio signal) takes a little more than an hour travel to Earth. The distance to Alpha Centauri is so great that light from these stars takes more than 4 years to reach our Solar System.
Thus, although Saturn seems a distant frontier, the nearest star is almost 30.000 times farther away.
This image is part of a stellar occultation sequence, during which Cassini watches as a star (or stars) as it passes behind Saturn. Light from the stars is attenuated by the uppermost reaches of Saturn's gaseous envelope, revealing information about the structure and composition of the Planet's Atmosphere.
The view was captured from about 66° above the Ring-Plane and faces southward on Saturn. Ring shadows mask the Planet's Northern Latitudes at bottom.
The image was taken in visible red light with the Cassini spacecraft narrow-angle camera on May 17, 2008. The view was obtained at a distance of approx. 534.000 Km (such as about 332000 miles) from Saturn. Image scale on Saturn is about 3 Km (approx. 2 miles) per pixel".MareKromium
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Anthe-PIA11100.jpgThe "Anthe Arc"66 visiteCaption NASA:"Caption NASA:"Cassini images reveal the existence of a faint "Arc of material" orbiting with Saturn's small moon Anthe.
The moon is moving downward and to the right in this perspective. In this image, most of the visible material in the Arc lies ahead of Anthe (2 Km, or a little more than 1 mile across) in its orbit. However, over time the moon drifts slowly back and forth with respect to the Arc.
The Arc extends over about 20° in Longitude (about 5,5% of Anthe's orbit) and appears to be associated with a gravitational resonance caused by the moon Mimas). Micrometeoroid impacts on Anthe are the likely source of the Arc material.
The orbit of Anthe lies between the larger moons Mimas and Enceladus. Anthe shares this region with two other small moons, Pallene (4 Km, or about 3 miles across) and Methone (3 Km, or approx. 2 miles across).
Methone also possesses an Arc (see PIA11102), while Pallene is known to orbit within a faint, complete ring of its own (see PIA08328).
Cassini imaging scientists believe the process that maintains the Anthe and Methone Arcs is similar to that which maintains the Arc in the G-Ring (see PIA08327). The general brightness of the image (along with the faint horizontal banding pattern) results from the long exposure time of 32" required to capture the extremely faint ring arc and the processing needed to enhance its visibility (which also enhances the digital background noise in the image). The image was digitally processed to remove most of the background noise. The long exposure also produced star trails in the background.
The image was taken in visible light with the Cassini Spacecraft narrow-angle camera on April 4, 2008. The view was acquired at a distance of approx. 1,2 MKM (such as about 746.000 miles) from Anthe and at a Sun-Anthe-Spacecraft Angle of 23°. Image scale is roughly 7 Km (about 4 miles) per pixel".MareKromium
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Anthe-PIA11101.jpgThe "Anthe Arc"54 visiteCaption NASA:"Cassini images reveal the existence of a faint "Arc of material" orbiting with Saturn's small moon Anthe.
The moon is moving downward and to the right in this perspective. In this image, most of the visible material in the Arc lies ahead of Anthe (2 Km, or a little more than 1 mile across) in its orbit. However, over time the moon drifts slowly back and forth with respect to the Arc.
The Arc extends over about 20° in Longitude (about 5,5% of Anthe's orbit) and appears to be associated with a gravitational resonance caused by the moon Mimas). Micrometeoroid impacts on Anthe are the likely source of the Arc material.
The orbit of Anthe lies between the larger moons Mimas and Enceladus. Anthe shares this region with two other small moons, Pallene (4 Km, or about 3 miles across) and Methone (3 Km, or approx. 2 miles across).
Methone also possesses an Arc (see PIA11102), while Pallene is known to orbit within a faint, complete ring of its own (see PIA08328).
Cassini imaging scientists believe the process that maintains the Anthe and Methone Arcs is similar to that which maintains the Arc in the G-Ring (see PIA08327). The general brightness of the image (along with the faint horizontal banding pattern) results from the long exposure time of 32" required to capture the extremely faint ring arc and the processing needed to enhance its visibility (which also enhances the digital background noise in the image). The image was digitally processed to remove most of the background noise. The long exposure also produced star trails in the background.
This view looks toward the un-illuminated side of the Rings from about 3° above the Ring-Plane.
The image was taken in visible light with the Cassini spacecraft narrow-angle camera on July 3, 2008. The view was obtained at a distance of approx. 1,2 MKM (such as about 739.000 miles) from Anthe and at a Sun-Anthe-Spacecraft, or Phase, Angle of 12°. Image scale is roughly 7 Km (about 4 miles) per pixel".MareKromium
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Anthe_Methone-PIA11102.jpgSmall - but VERY bright - Companions: Anthe and Methone55 visiteCaption NASA:"Recent Cassini images show Arcs of Material co-orbiting with the Saturnian moons Anthe and Methone.
Arrows indicate the positions of Anthe, at top left, and Methone, at bottom right. Micrometeoroid impacts on the moons are the likely source of the Arc Material.
Cassini imaging scientists believe the process that maintains the Anthe and Methone arcs is similar to that which maintains the Arc in the G-Ring (see PIA08327). The general brightness of the image (along with the faint horizontal banding pattern) results from the long exposure time of 15" required to capture the extremely faint ring arc and the processing needed to enhance its visibility (which also enhances the digital background noise in the image).
The image was digitally processed to remove most of the background noise. This view looks toward the un-illuminated side of the Rings from about 2° above the Ring-Plane.
The image was taken in visible light with the Cassini Spacecraft narrow-angle camera on Oct. 29, 2007. The view was acquired at a distance of approx. 2,3 MKM (about 1,4 MMs) from Anthe and 2,2 MKM (approx. 1,4 MMs) from Methone.
Image scale is roughly 14 Km (about 9 miles) per pixel on Anthe and 13 Km (approx. 8 miles) on Methone".MareKromium
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Atlas and others-PIA06522_modest.jpgSaturn's Rings + Atlas, Prometheus and Janus75 visiteCaption NASA originale: "Saturn hosts its own miniature solar system with an entourage of more than 30 moons. This image shows Saturn's "A" and "F" Rings, along with 3 of the moons that orbit close to them. From innermost to outermost, tiny Atlas (32 Km across) orbits just outside of the bright "A-Ring" and is seen above center in this view. Prometheus (102 Km across) is visible near lower right. Prometheus and its smaller cohort, Pandora, shepherd the thin, knotted F-Ring. Janus (181 Km across) can be seen near lower left. Janus shares its orbit with the moon Epimetheus. Density waves due to Janus cause some of the bright bands seen in the A-Ring in this image. Prometheus and Atlas also produce waves in the rings, but their wave regions are too narrow to be seen here. The planet's shadow stretches all the way across the main rings in this view. The shadow has an oval shape now but over the next few years it will become more rectangular as the planet orbits the Sun and the angle Sunlight-Rings decreases".
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Atlas from Voyager 1.jpgAtlas from Voyager 2108 visiteUna "roccia vagante" (forse un KBO---->Kuiper's Belt Object) catturato da Saturno mentre si dirigeva verso l'interno del Sistema Solare? Una "cometa mancata" dunque? Nessuno può saperlo, naturalmente...
L'unica cosa che possiamo notare e stigmatizzare è l'incredibile forma di questa piccolissima Luna Saturniana la quale, a dispetto della modestia delle sue dimensioni - e forse con un pizzico di ironia... -, è stata battezzata "Atlas".
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Atlas from Voyager2.jpgAtlas, from Voyager 2 (extra detail mgnf)67 visiteUn buon super detail-mgnf per evidenziare la forma (curiosa) della mini-luna Saturniana Atlas, sino ad ora mai ripresa in maniera soddisfacente dalle Sonde che sono passate (o sono tuttora in transito) nello Spazio di Saturno.
Il frame è stato portato a stretch estremi dal nostro Tecnico delle Immagini ed il risultato è più che decoroso; tuttavia, proprio perchè lo stretch estremo crea o concorre nella creazione di anomalìe ed artefatti, non commentiamo i dettagli "strani" che questo frame ora pare evidenziare.
O meglio: li commenteremo se anche Voi li vedrete e chi chiederete conto di essi...
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Atlas from appx. 23.685.000.jpgAtlas from approx. 23.685.000 Km63 visitenessun commento
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Atlas, Pandora and Janus-PIA06522_modest.jpgSaturn's Rings + Atlas, Pandora, Prometheus and Janus77 visiteCaption NASA originale: "Saturn hosts its own miniature solar system with an entourage of more than 30 moons. This image shows Saturn's "A" and "F" Rings, along with three of the moons that orbit close to them. From innermost to outermost, tiny Atlas (32 Km across) orbits just outside of the bright "A-Ring" and is seen above center in this view. Prometheus (102 Km across) is visible near lower right. Prometheus and its smaller cohort, Pandora, shepherd the thin, knotted F-Ring. Janus (181 Km across) can be seen near lower left. Janus shares its orbit with the moon Epimetheus. Density waves due to Janus cause some of the bright bands seen in the A-Ring in this image. Prometheus and Atlas also produce waves in the rings, but their wave regions are too narrow to be seen here. The planet's shadow stretches all the way across the main rings in this view. The shadow has an oval shape now but over the next few years it will become more rectangular as the planet orbits the Sun and the angle Sunlight-Rings decreases.
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Atlas,_Daphins_and_Pan-PIA21449.jpgAtlas, Daphnis and Pan155 visiteCaption NASA:"This montage of views from NASA's Cassini Spacecraft shows three of Saturn's Small Ring moons: Atlas, Daphnis and Pan at the same scale for ease of comparison.
Two differences between Atlas and Pan are obvious in this montage. Pan's Equatorial Band is much thinner and more sharply defined, and the central mass of Atlas (the part underneath the smooth Equatorial Band) appears to be smaller than that of Pan.
All of these images were taken using the Cassini Spacecraft Narrow-Angle Camera. The images of Atlas were acquired on April 12, 2017, at a distance of about 10.000 miles (approx. 16,0093 Km) and at a Sun-moons-Spacecraft angle (or Phase Angle) of 37°. All three images are oriented so that North is up".MareKromium
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