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Neptune-PIA01982.jpgClouds near the "Eye" of Neptune (Natural Colors; credits: Lunexit)82 visiteCaption NASA:"The bright cirrus-like clouds of Neptune change rapidly, often forming and dissipating over periods of several to tens of hours. In this sequence, Voyager 2 observed cloud evolution in the region around the Great Dark Spot (GDS).
The surprisingly rapid changes which occur separating each panel shows that in this Region Neptune's weather is perhaps as dynamic and variable as that of the Earth. However, the scale is immense by our standards -- the Earth and the GDS are of similar size -- and in Neptune's frigid Atmosphere, where temperatures are as low as 55 degrees Kelvin (-360 F), the cirrus clouds are composed of frozen Methane rather than Earth's crystals of water ice".MareKromium
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Neptune-PIA01995.jpgSouth Polar Clouds and Shadows (Natural Colors; credits: Lunexit)55 visiteCaption NASA:"This image of Neptune's South Polar Region was obtained by the NASA Voyager 2 Probe narrow-angle camera on Aug. 23, 1989, when it was at a distance of about 25 MKM (about 1,6 MMs).
The smallest cloud features are 45 Km (about 28 miles) in diameter. Also this image shows the discovery of shadows in Neptune's Atmosphere, shadows cast onto a deep cloud bank by small elevated clouds. Located at about 68° South Lat., they are the first cloud shadows ever seen by the Voyager on any Planet.
The dark regions adjacent to the small bright clouds are believed to be shadows, because they are on the side of the cloud that is opposite to the incoming Sunlight and also because they lengthen in places where the Sun lies closer to the horizon".MareKromium
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Neptune-PIA01998.jpgNeptune, from FAR away...54 visiteCaption NASA originale:"This image of Neptune was taken through the clear filter of the narrow-angle camera, when the Voyager 2 spacecraft was at a range of 57 MKM (about 35 MMs). The image was processed by computer to show the newly resolved dark oval feature embedded in the middle of the dusky southern collar. The large dark spot nearer the equator is also prominent on the left edge of the disk. The new small dark spot rotates faster than the large dark spot indicating that the winds on Neptune have different velocities at different latitudes as is the case for Jupiter, Saturn and Uranus".
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Neptune-PIA02209_modest.jpgNeptune from 176.000.000 Km - Voyager 261 visiteCaption NASA originale:"These pictures of Neptune were obtained by Voyager 2 on April 26,1989, at a distance of 176 MKM. At the center of the Neptune disc, each pixel covers a square 4° by 4° in latitude. (Each Voyager image contains 800 pixels, picture elements, per line and 800 lines.) Resolution here was 3256 Km per line pair. The violet, clear and orange filters of Voyager's narrow-angle camera were used to produce the color pictures. Image processing enhances contrast of the features. The picture on the right was taken five hours after that at left, during which time the planet rotated 100°. The dark spot visible in the left picture appeared in clear filter images obtained three months earlier. A much brighter, white spot, prominent in the earlier images, has now apparently faded. The white spot near the south pole in the right picture is new. It was visible only faintly in a picture taken 18 hours earlier at the same longitude. This evidence of dynamic activity was unexpected in Neptune's atmosphere because Neptune receives only one-tenth of one percent as much solar energy as does the Earth".
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Neptune-PIA02220.jpgSouth Polar Clouds and Shadows (Natural Colors; credits: Lunexit)55 visiteCaption NASA:"This image of Neptune shows the discovery of shadows in Neptune's Upper Atmosphere, shadows cast onto a deep cloud band by small elevated clouds. They are the first cloud shadows ever seen by Voyager on any Planet. Estimates of the height of these discrete clouds above the underlying cloud bank can be obtained by careful analysis of this data".MareKromium
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Neptune-PIA02245.jpgNeptune from 16.000.000 Km55 visiteCaption NASA originale:"This color image, produced from a distance of about 16 MKM, shows several complex and puzzling atmospheric features. The Great Dark Spot (GDS) seen at the center is about 13.000 Km by 6.600 km in size - as large along its longer dimension as the Earth. The bright, wispy "cirrus-type" clouds seen hovering in the vicinity of the GDS are higher in altitude than the dark material of unknown origin which defines its boundaries".
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Neptune-PIA09927.jpgThe "Hot" South Pole of Neptune54 visiteCaption NASA:"These thermal images show a "hot" South Pole on the Planet Neptune. These warmer temperatures provide an avenue for Methane to escape out of the deep atmosphere.
The images were obtained with the Very Large Telescope in Chile, using an imager/spectrometer for mid-infrared wavelengths on Sept. 1 and 2, 2006.
The telescope is operated by the European Organization for Astronomical Research in the Southern Hemisphere (known as ESO).
Scientists say Neptune's South Pole is "hotter" than anywhere else on the Planet by about 10° Celsius (50 degrees Fahrenheit). The average temperature on Neptune is about -200° Celsius (-392 degrees Fahrenheit).
The upper left image samples temperatures near the top of Neptune's troposphere (near 100 millibar pressure, which is 1/10th the Earth atmospheric pressure at sea level). The hottest temperatures are indicated at the lower part of the image, at Neptune's south pole (see the graphic at the upper right).
The lower two images, taken 6.3 hours apart, sample temperatures at higher altitudes in Neptune's stratosphere. They do show generally warmer temperatures near, but not at, the south pole. They also show a distinct warm area which can be seen in the lower left image and rotated completely around the back of the planet and returned to the earth-facing hemisphere in the lower right image".MareKromium
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Neptune-PIA21629.jpgNeptune from the Saturnian Sky (Natural Colors; credits: NASA/JPL-Caltech/Space Science Institute)118 visiteCaption NASA:"On August 25, 1989, NASA's Voyager 2 made its historic Fly-By of Neptune and its largest moon, Triton. The Cassini Spacecraft took this image to celebrate the anniversary of that event.
Neptune appears in this Natural Color composite as a pale blue disk (similar to Cassini's image of Uranus from 2014), just below and to the right of image center. Most of the faint specks in the image are background stars, although some are likely Cosmic Rays (charged particles that strike the camera detector).
By imaging Neptune, Cassini's Solar System family portrait-taking is complete. The Mission's Planetary Photojournal includes all of the major Planets except Mercury, which is too close to the Sun to be imaged, as well as dwarf planet Pluto.
This view was acquired by the Cassini narrow-angle camera on Aug. 10, 2017, at a distance of approximately 2,72 Billion Miles (such as approx. 4,38 BKM) from Neptune. Red, blue and green filter images were combined to create this Natural Color image".MareKromium
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Neptune-South_Hem-V2-PIA00050_modest.jpgThe Southern Polar Region of Neptune from approx. 4.200.000 Km65 visiteGli Scienziati, analizzando le immagini fornite dalla Sonda Voyager 2, si sono convinti che il sistema atmosferico di Nettuno sia molto simile a quello di Giove: queste grandi formazioni nuvolose bianche riprese dalle fotocamere della Sonda si formano, al pari dei venti che le sospingono, nelle zone equatoriali del Pianeta. Poi, spostandosi verso Sud, questi venti diventano sempre più veloci e violenti. Un sistema configurato in maniera interessante ma, probabilmente, piuttosto instabile.
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Neptune-StrechedNaturalColors.JPGNeptune and a few of His Moons (Voyager 2 - Natural, but enhanced, Colors; credits: NASA)69 visiteCaption NASA:"Voyager 2 was the first spacecraft to observe the planet Neptune and its two satellites: Triton, the largest, and Nereid.
The most obvious feature of the Planet is its blue color, the result of Methane in the Atmosphere. Research continues on Neptune's two largest satellites and the additional 6 that were discovered by Voyager 2's investigation". MareKromium
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Neptune-V2.jpgBright Neptunian Clouds92 visiteCaption NASA:"This Voyager 2 HR Natural Color image, taken about two hours before closest approach, provides obvious evidence of vertical relief in Neptune's bright Cloud Streaks. These clouds were observed at a latitude of 29° North near Neptune's Eastern Terminator. The linear cloud forms are stretched approximately along lines of constant latitude and the Sun is toward the lower left.
The bright sides of the clouds which face the sun are brighter than the surrounding cloud deck because they are more directly exposed to the Sun.
Shadows can be seen on the side opposite the Sun. These shadows are less distinct at short wavelengths (violet filter) and more distince at long wavelengths (orange filter). This can be understood if the underlying cloud deck on which the shadow is cast is at a relatively great depth, in which case scattering by moleculres in the overlying Atmosphere will diffuse light into the shadow. Because molecules scatter blue light much more efficiently than red light, the shadows will be darkest at the longest (reddest) wavelengths, and will appear blue under white light illumination.
The resolution of this image is roughly 11 Km (about 6,8 miles) per pixel and the range is only 157.000 Km (approx. 98.000 miles). The width of the Clouds Streaks range from about 50 to about 200 Km (approx. 31 to 124 miles), and their shadow widths range from about 30 to about 50 Km (approx. 18 up to 31 miles). Cloud heights appear to be of the order of approx. 50 Km (about 31 miles).MareKromium
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Neptune-V2.pngCrescent Neptune (August 1989)435 visite(ANSA) - ROMA, 18 AGOSTO 2022 - Compie 45 anni la sonda Voyager 2, la più longeva dell'era spaziale.
Lanciata il 20 agosto 1977, la sonda ha superato i confini del Sistema Solare nel 2018 ed è ancora attiva nello Spazio Interstellare, dal quale ha recentemente inviato dati mai visti (vedi Nota 1). Con la sua gemella Voyager 1, lanciata 15 giorni più tardi, la Voyager 2 è la protagonista di una missione da record. Gestite dal Jet Propulsion Laboratory (Jpl) della Nasa, le due sonde sono anche messaggeri molto speciali, che stanno portando nello spazio interstellare un biglietto da visita della Terra e dei suoi abitanti: un disco placcato in oro progettato per durare oltre un miliardo di anni, che contiene le immagini e suoni della vita sul nostro pianeta, diagrammi di leggi scientifiche fondamentali e saluti in molte lingue.
Entrambe le Sonde Voyager hanno attraversato il Sistema Solare rincorrendosi, con la Voyager 1 che ha raggiunto Giove e Saturno prima della sua compagna, mentre la Voyager 2 è stata la prima e finora l'unica sponda ad avvicinarsi a Urano, nel 1986, e poi a Nettuno, nel 1989, inviando a Terra le prime immagini ravvicinate di quei pianeti lontani, Nel 2013 la Voyager 1 era stata la prima a inoltrarsi nello spazio interstellare, seguita sei anni dopo dalla sua gemella. "Entrambe le sonde continuano a inviare all'umanità osservazioni da territori inesplorati", osserva la vice-responsabile scientifica del progetto, Linda Spilker, del Jpl. Le due Voyager "continuano a fare scoperte soprendenti", ha aggiunto la responsabile della missione Suzanne Dodd. "Non sappiamo per quanto tempo ancora la missione proseguirà, ma siamo sicuri che continuerà a regalarci molte sorprese scientifiche" (vedi Nota 2).
Nota 1: quali?
Nota 2: quali?
Come al solito: sensazionalismo di portata, condito dal nulla. Bellissima immagine comunque. L'aura più luminosa e bluastra che copre la porzione Sx del frame potrebbe essere un effetto del Sole. Ma non ho info al riguardo.MareKromium
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