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Pluto-421596main_s1006ay-1.jpgSurface Color-Variations on Pluto57 visiteSince its discovery in 1930, Pluto has been a speck of light in the largest ground-based telescopes. But NASA's Hubble Space Telescope has now mapped the Dwarf Planet in never-before-seen detail. The new map is so good, astronomers have even been able to detect changes on the Dwarf Planet's Surface by comparing Hubble images taken in 1994 with the newer images taken in 2002-2003. The task is as challenging as trying to see the markings on a soccer ball 40 miles away.
Hubble's view isn't sharp enough to see craters or mountains, if they exist on the surface, but Hubble reveals a complex-looking and variegated world with white, dark-orange, and charcoal-black terrain. The overall color is believed to be a result of UltraViolet radiation from the distant Sun breaking up Methane that is present on Pluto's Surface, leaving behind a dark, molasses-colored, carbon-rich residue.
Astronomers were very surprised to see that Pluto's brightness has changed — the Northern Pole is brighter and the Southern Hemisphere is darker and redder. Summer is approaching Pluto's North Pole, and this may cause surface ices to melt and refreeze in the colder shadowed portion of the Planet. The Hubble pictures underscore that Pluto is not simply a ball of ice and rock but a dynamic world that undergoes dramatic atmospheric changes.MareKromium
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Pluto-421596main_s1006ay-2.jpgSurface Color-Variations on Pluto57 visiteNASA today released the most detailed set of images ever taken of the distant dwarf planet Pluto. The images taken by NASA's Hubble Space Telescope show an icy and dark molasses-colored, mottled world that is undergoing seasonal changes in its surface color and brightness. Pluto has become significantly redder, while its illuminated Northern Hemisphere is getting brighter. These changes are most likely consequences of surface ices sublimating on the sunlit Pole and then refreezing on the other Pole as the dwarf planet heads into the next phase of its 248-year-long seasonal cycle. The dramatic change in color apparently took place in a two-year period, from 2000 to 2002.
The Hubble images will remain our sharpest view of Pluto until NASA's New Horizons probe is within 6 months of its Pluto flyby. The Hubble pictures are proving invaluable for picking out the planet's most interesting-looking hemisphere for the New Horizons spacecraft to swoop over when it flies by Pluto in 2015.
Though Pluto is arguably one of the public's favorite planetary objects, it is also the hardest of which to get a detailed portrait because the world is small and very far away. Hubble resolves surface variations a few hundred miles across, which are too coarse for understanding Surface Geology. But in terms of surface color and brightness Hubble reveals a complex-looking and variegated world with white, dark-orange, and charcoal-black terrain. The overall color is believed to be a result of UltraViolet radiation from the distant Sun breaking up Methane that is present on Pluto's Surface, leaving behind a dark and red carbon-rich residue.
When Hubble pictures taken in 1994 are compared with a new set of images taken in 2002 to 2003, astronomers see evidence that the northern polar region has gotten brighter, while the southern hemisphere has gotten darker. These changes hint at very complex processes affecting the visible surface, and the new data will be used in continued research.
The images are allowing planetary astronomers to better interpret more than three decades of Pluto observations from other telescopes, says principal investigator Marc Buie of the Southwest Research Institute in Boulder, Colo. "The Hubble observations are the key to tying together these other diverse constraints on Pluto and showing how it all makes sense by providing a context based on weather and seasonal changes, which opens other new lines of investigation."
The Hubble pictures underscore that Pluto is not simply a ball of ice and rock but a dynamic world that undergoes dramatic atmospheric changes. These are driven by seasonal changes that are as much propelled by the Planet's 248-year elliptical orbit as its axial tilt, unlike Earth where the tilt alone drives seasons. The seasons are very asymmetric because of Pluto's elliptical orbit. Spring transitions to Polar Summer quickly in the Northern Hemisphere because Pluto is moving faster along its orbit when it is closer to the Sun.
Ground-based observations, taken in 1988 and 2002, show that the mass of the atmosphere doubled over that time. This may be due to warming and sublimating Nitrogen ice. The new Hubble images from 2002 to 2003 are giving astronomers essential clues about how the seasons on Pluto work and about the fate of its atmosphere.
The images, taken by the Advanced Camera for Surveys, are invaluable to planning the details of the New Horizons flyby in 2015. New Horizons will pass by Pluto so quickly that only one hemisphere will be photographed in the highest possible detail. Particularly noticeable in the Hubble image is a bright spot that has been independently noted to be unusually rich in carbon monoxide frost. It is a prime target for New Horizons. "Everybody is puzzled by this feature," says Buie. New Horizons will get an excellent look at the boundary between this bright feature and a nearby region covered in pitch-black surface material.
"The Hubble images will also help New Horizons scientists better calculate the exposure time for each Pluto snapshot, which is important for taking the most detailed pictures possible," says Buie. With no chance for re-exposures, accurate models for the surface of Pluto are essential in preventing pictures that are either under- or overexposed.
The Hubble images are a few pixels wide. But through a technique called dithering, multiple, slightly offset pictures can be combined through computer-image processing to synthesize a higher-resolution view than could be seen in a single exposure. "This has taken four years and 20 computers operating continuously and simultaneously to accomplish," says Buie, who developed special algorithms to sharpen the Hubble data.
The Hubble research results appear in the March 2010 issue of the Astronomical Journal. Buie's science team members are William Grundy of Lowell Observatory in Flagstaff, Ariz., and Eliot Young, Leslie Young, and Alan Stern of Southwest Research Institute in Boulder, Colo.
Buie plans to use Hubble's new Wide Field Camera 3 to make further Pluto observations prior to the arrival of New Horizons.MareKromium
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ZJ-Charon.gifCharon (the surface - speculation)56 visiteOriginal caption:"This image shows 4 views of Pluto's moon Charon.
The images are centered in 0° Lat. and 0° (top-left), 90° (top-right), 180° (bottom-left) and 270° (bottom-right) Long.
The images are based on photometric measurements of Marc Bouie/Lowell Observatory".
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ZV-Pluto System-HST~0.jpgHubble Space Telescope confirms NEW MOONS of Pluto!56 visiteAnxiously awaited follow-up observations with NASA's HST have confirmed the presence of two new moons around the distant planet Pluto. The moons were first discovered by Hubble in May 2005, but the science team probed even deeper into the Pluto System last week to look for additional satellites and to characterize the orbits of the moons.
Though the team had little doubt the moons are real, they were happy to see the moons show up very close to the locations predicted from the earlier Hubble observations. The initial discovery is being reported today in this week's edition of magazine "Nature".
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ZK-CharonMap.jpgThe surface of Charon (speculation)55 visiteOriginal caption:"This is the first surface map of Charon, the moon of the Solar System's most remote planet, Pluto. The map is only based on photometric measurements and it covers the entire surface of the moon. (Courtesy A.Tayfun Oner, based on pictures courtesy of Marc Buie/Lowell Observatory)
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ZO-Pluto System.jpgPluto's System: Facts, Data, Men and early Picture55 visiteFast Facts — Recent Technical information (Oct. 2005)
Object Name: Pluto
Object Description: Planet
Distance: Although its orbit is highly eccentric, Pluto's average distance from the Sun is 39,44 Astronomical Units (A.U.) or roughly 3,6 BMs (such as about 5,9 BKM).
Dimensions: Pluto has a diameter of roughly 1.475 miles (about 2.280 Km) at the equator.
About the Data Description: these HST data are from proposal 10427: H.A. Weaver (JHU/APL), M.W. Buie (Lowell Obs.), S.A. Stern, J.R. Spencer, E. Young, and L.A. Young (SwRI); and proposal 9391: M.W. Buie and W.M. Grundy (Lowell Obs.), E. Young, L.A. Young, and S.A. Stern (SwRI). M. Mutchler (STScI) and A.J. Steffl (SwRI) are also on the science team.
Instrument: ACS/WFC ACS/HRC
Exposure Date(s): May 15/18, 2005 various dates in 2002 and 2003
Filters: F606W (V) F475W (B) and F555W (V)
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ZQ-Pluto System 02.jpgPluto's System: the observations of June 200255 visiteA careful search of HST images taken with the ACS/HRC on June 14th, 2002, reveals two objects that are consistent with the expected locations of the newly-discovered satellites. One image (top) was taken in yellow light (555 nm) and the other (bottom) was taken in blue light (475 nm). The ellipse shows the orbital path of the new satellites derived from the May 2005 HST observations. The satellites should lie somewhere along this ellipse and, indeed, there are two objects along the predicted path, thus confirming the 2005 observations.
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ZW-Pluto & Companions.jpgNix and Hydra!55 visiteDa "NASA - Picture of the Day" del 24 Giugno 2006:"Discovered in mid-2005, Pluto's small moons were provisionally designated S/2005 P1 and S/2005 P2.
They have now been officially christened Nix and Hydra.
Compared to Pluto and its large moon Charon, at 2.360 and 1.210 Km in diameter respectively, Nix (inner moon) and Hydra (outer moon) are tiny, estimated to be only 40 to 160 Km across. Pluto and Charon are bright enough to create diffraction spikes in this HST image, but Nix and Hydra are some 5.000 times fainter than Pluto and appear only as small points of light. Still, their new names are appropriate for the distant Pluto System. In mythology, Nix was the goddess of Darkness and Night and the mother of Charon, while Hydra was a nine headed monster and is now orbiting the Solar System's 9th planet.
Of course Nix and Hydra also share initials with the pluto-bound spacecraft New Horizons".
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ZZ-New_Horizons-02.jpgOn the way to Pluto: through the Jupiter System (3)55 visiteCaption NASA:"This image shows New Horizons' path through the Jupiter System; the inset shows the location of Jupiter's four largest moons, Io, Ganymede, Europa and Callisto.
New Horizons will turn its science instruments toward the moons as well as the giant planet".
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ZZ-Pluto-PIA09234.gifPluto! From New Horizons (GIF-Movie)55 visiteCaption NASA:"The Long Range Reconnaissance Imager (LORRI) on New Horizons acquired images of the Pluto field 3 days apart in late September 2006, in order to see Pluto's motion against a dense background of stars. LORRI took 3 frames at 1-second exposures on both Sept. 21 and Sept. 24.
Because it moved along its predicted path, Pluto was detected in all six images.
These images are displayed using false-color to represent different intensities: the lowest intensity level is black, different shades of red mark intermediate intensities, and the highest intensity is white. The images appear pixilated because they were obtained in a mode that compensates for the drift in spacecraft pointing over long exposure times. LORRI also made these observations before operators uploaded new flight-control software in October; the upgraded software package includes an optical navigation capability that will make LORRI approximately three times more sensitive still than for these Pluto observations".MareKromium
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ZL-The Moons of Pluto.jpgNew "moons" for Pluto? Early news (first picture at LR)54 visiteTwo small moons have been discovered orbiting Pluto, bringing the Planet's retinue of known satellites to 3 and leaving scientist to wonder how it could be.
The newfound moons orbit about 27.000 miles (44.000 Km) from Pluto, more than twice as far as Charon, Pluto's other satellite, and they are 5000 times dimmer than Charon.
Preliminary observations suggest they are in circular orbits around Pluto and in the same plane as Charon, said Hal Weaver of the Johns Hopkins Applied Physics Laboratory.
"That suggests they probably formed at the same time as Charon" Weaver told SPACE.com in a telephone interview. NASA planned a teleconference with reporters to announce the discovery.
While scientists had predicted there might be more moons, the newfound setup is surprising nonetheless, in part because Pluto is smaller than our own Moon.
"It's almost like a mini Solar System" Weaver said.
How can something about 70% the size of Earth's Moon have all these satellites? How can that happen?".
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ZM-The Moons of Pluto.jpgNew "moons" for Pluto? Early news54 visiteThe leading theory for the formation of Charon involves a large object striking Pluto. The debris from that collision could have formed the two smaller moons, Weaver speculates. It can't be ruled out that they might have been captured into the System, but that seems very unlikely, he said. The two new moons are between 30/40 and 100/125 miles (48/64 to 160/200 Km) in diameter. There is not enough data to pin their size down exactly, however. The moons were found using the HST.
The moons are catalogued as S/2005 P1 and S/2005 P2 for now.
Once they are confirmed, the discoverers will suggest names, to be approved by the IAU (International Astronomical Union).
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