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| Ultimi arrivi - Pluto and Charon: The "Double Planet" |
ZZ-ZZ-ZZ-ZZ-ZZ-20110401_0515.jpgWhere's New Horizons? April 2011 (1) - Current Position (beyond Uranus' Orbit)120 visiteThis image shows New Horizons' "Current Position". The green segment of the line shows where New Horizons has traveled since launch; the red indicates the Spacecraft's path toward Jupiter, Pluto and beyond. Positions of stars with magnitude 12 or brighter are shown from this perspective, which is above the Sun and "north" of Earth's orbit.
Notes: what Is an AU? The graphics on these pages note New Horizons' distance from Earth, Jupiter and Pluto in AU, or Astronomical Units. One AU is the average distance between the Sun and Earth, such as about 93 Million Miles (MMs) or 149,6 Million Kilometers (MKM).
Heliocentric Velocity. The Current Position graphic also notes the Spacecraft's "Heliocentric Velocity" - such as its speed with respect to the Sun - in Kilometers per second (Km/sec). One Km/sec is equivalent to 0,62 miles per second (Mi/sec), or 2237 miles per hour (mph).
New Horizons crossed the orbit of Uranus at approximately 18:00 EDT on March 18, 2011, with the Spacecraft more than 1,8 Billion Miles (nearly 2,9 Billion Kilometers) from Earth. Uranus was 2,4 BMs (3,8 BKM) from New Horizons at the time and the Spacecraft was cruising in "Electronic Sleep Mode".MareKromiumApr 23, 2011
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ZZ-ZZ-ZZ-ZZ-ZZ-Nhov20110401_0515.jpgWhere's New Horizons? April 2011 (2) - Full Trajectory: Overhead View 113 visiteThis image shows New Horizons' Current Position along its full planned trajectory. The green segment of the line shows where New Horizons has traveled since launch; the red indicates the Spacecraft's future path. Positions of stars with magnitude 12 or brighter are shown from this perspective, which is above the Sun and "north" of Earth's orbit.MareKromiumApr 23, 2011
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ZZ-ZZ-ZZ-ZZ-ZZ-Nhsv-20110401_0515.jpgWhere's New Horizons? April 2011 (3) - Full Trajectory - Side View 114 visiteAlso this image shows New Horizons' Current Position along its full planned trajectory. The green segment of the line shows where New Horizons has traveled since launch; the red indicates the Spacecraft's future path. Positions of stars with magnitude 12 or brighter are shown from this perspective, which is slightly above the Orbital Plane of the Planets. MareKromiumApr 23, 2011
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ZZ-ZZ-ZZ-ZZ-20100727_LORRILooksBack_lg.jpgOn the Way to Pluto: Jupiter, Europa and Ganymede98 visiteCaption NASA:"New Horizons had an exciting Fly-By encounter with Jupiter in early 2007, and the Spacecraft has been rapidly moving away from the Giant Planet ever since.
The New Horizons team looked back at Jupiter during Annual Checkout (ACO) to test the Long Range Reconnaissance Imager (LORRI)'s ability to image targets close, in angle, to the Sun.
This image was taken on June 24, 2010, when New Horizons was 16,3 Astronomical Units (about 1,5 Billion Miles) from Jupiter, at a Spacecraft-Sun-Planet angle of only 17°. Looking like Earth's moon at a quarter phase, Jupiter is clearly resolved, with an apparent diameter of nearly 12 LORRI pixels. LORRI also picks up the moons Ganymede and Europa, even though the exposure time was only 9 milliseconds and these Galilean satellites are extremely faint in comparison to Jupiter".MareKromiumDic 14, 2010
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ZZ-ZZ-ZZ-ZZ-20100727_LORRIM_lg.jpgOn the Way to Pluto: Messier 779 visiteCaption NASA:"The New Horizons team calibrates the Long Range Reconnaissance Imager (LORRI) by taking pictures of the Open Star Cluster Messier 7 (M 7). This is the first LORRI image of M 7 taken during Annual Checkout (ACO); the 100-millisecond manual exposure was taken on June 25, 2010. A preliminary comparison of this image to a 2008 LORRI picture of M7 indicated no degradation or change in LORRI's performance".MareKromiumDic 14, 2010
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ZZ-ZZ-ZZ-ZZ-20100727_LORRINeptune_lg.jpgOn the Way to Pluto: Neptune's on sight!79 visiteCaption NASA:"The New Horizons Long Range Reconnaissance Imager (LORRI) observed Neptune on June 23, 2010, as part of a test of the critical Optical Navigation Annual Checkout (ACO).
In this 100-millisecond exposure, taken when the Spacecraft was 23,2 Astronomical Units (about 2,15 Billion Miles) from Neptune, the Planet appears slightly larger than a star. At the time of this observation, the Solar Phase Angle was 34° and the Solar Elongation Angle (Planet-Spacecraft-Sun) was 95°.
Only New Horizons can observe Neptune at such large Solar Phase Angles, which can be used to study the light-scattering properties of Neptune's Atmosphere".MareKromiumDic 14, 2010
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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.MareKromiumFeb 05, 2010
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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.MareKromiumFeb 05, 2010
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C-Pluto_Charon.jpgPluto and Charon, from the Subaru Telescope54 visiteThe excellent quality of its 8,3-meter primary mirror and the stability of the atmosphere above Mauna Kea, Hawaii, allowed the Subaru Telescope to provide clearly separated images of Pluto and Charon using its Cooled Infrared Spectrograph/Camera.
This image is produced from three 2-second exposures taken through infrared filters on June 9, 1999.
MareKromiumLug 20, 2008
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B-Caron.jpgThe Discovey of Charon54 visiteCharon was discovered in June 1978 by U.S. Naval Observatory astronomers James Christy and Robert Harrington. They weren't even looking for satellites of Pluto - they were trying to refine Pluto's orbit around the Sun!
Charon was discovered when sharp-eyed Christy noticed the images of Pluto were strangely elongated - it looked like Pluto had an irregular blob attached to its side. Perhaps the telescope was joggled when the picture was taken? No, that possibility was quickly eliminated by noticing that the other stars on the photo were round. Moreover, the blob itself seemed to move around Pluto - the direction of elongation cycled back and forth over 6.39 days - Pluto's rotation period. From this, Christy, after being checked by Harrington, concluded that Pluto either possessed a mountain thousands of kilometers high or a satellite that orbited in its synchronous orbit.
Searching through their archives of Pluto images taken years before, Christy found more cases where Pluto appeared strangely elongated. Working independently, Christy measured the angle (from north) where the elongations appeared while Harrington calculated what the answer "should be" if the elongation was caused by an orbiting satellite. When the anxious moment came for them to compare their answers, they found perfect agreement. Just to be sure, they waited for the U. S. Naval Observatory 60-inch telescope to make one more confirmation. And sure enough, on July 2 new images showed the elongation due to a satellite right where it was supposed to be. They announced their discovery to the world on July 7, 1978. Christy proposed the name "Charon", after the mythological ferryman who carried souls across the river Acheron, one of the five mythical rivers that surrounded Pluto's underworld. Apart from the mythological connection for this name, Christy chose it because the first four letters also matched the name of his wife, Charlene.
Charon's satellite status was finally confirmed when Pluto and Charon began a series of mutual eclipses in 1985. Later, Hubble Space Telescope and even advanced ground-based telescopes were able to spot Charon orbiting nearby — just 1/4000th of a degree from Pluto!MareKromiumLug 20, 2008
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ZZ-ZZ-Nhsv3-060808_NHpassSaturn.jpgWhere's New Horizons? June 2008 - Full Trajectory: Overhead View54 visiteNew Horizons crossed the orbit of Saturn on June 8, passing yet another interplanetary milepost on its voyage to Pluto and the icy environs of the Kuiper Belt.
Spinning in healthy, electronic hibernation, New Horizons reached a distance of 10.06 AU (Astronomical Units; such as about 935 MMs or about 1,5 BKM) from the Sun at 10:00 UT (Universal Time), becoming the first spacecraft to journey beyond Saturn’s orbit since Voyager 2 passed the ringed planet nearly 27 years ago. In fact, Voyager 1 and 2, at the edge of the Sun’s Heliosphere some 100 AU away, are the only Spacecrafts operating farther out than New Horizons.
New Horizons reached Saturn's distance just two years and four months after launch - by far a faster transit to Saturn than any previous spacecraft. (Voyager 1, the previous record holder, made the trip in approximately three years and two months)
New Horizons has crossed the orbits of three planets since its launch in January 2006, though only one – Jupiter, in February 2007 – was close enough for a gravity boost and for the Spacecraft to study. Saturn is more than 1,4 BMs (about 2,3 BKM) from New Horizons at present.
After a productive two-week series of system checks, maintenance activities, and software and command uploads,the Spacecraft is humming through the Outer Solar System at a speed of 40.850 miles (65.740 Km) per hour. The New Horizons Team expects to keep the Spacecraft in hibernation until Sept. 2, 2008. MareKromiumGiu 10, 2008
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ZZ-ZZ-ZZ-Pluto-lorri_pluto_im01_1x1_oct2007_ppt.pngPluto54 visiteThis image demonstrates the first detection of Pluto using the High-Resolution mode on the New Horizons Long-Range Reconnaissance Imager (LORRI). The mode provides a clear separation between Pluto and numerous nearby background stars. When the image was taken on October 6, 2007, Pluto was located in the constellation Serpens, in a region of the sky dense with background stars.
Typically, LORRI’s exposure time in Hi-Res mode is limited to approx. 0,1", but by using a special pointing mode that allowed an increase in the exposure time to 0,967", scientists were able to spot Pluto, which is approximately 15.000 times fainter than human eyes can detect.
New Horizons was still too far from Pluto (3,6 BKM, or 2,2 BMs) for LORRI to resolve any details on Pluto’s surface – that won’t happen until Summer 2014, approximately one year before closest approach. For now the entire Pluto System remains a bright dot to the Spacecraft’s telescopic camera, though LORRI is expected to start resolving Charon from Pluto – seeing them as separate objects – in summer 2010.MareKromiumFeb 12, 2008
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