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Jupiter's Moons
On Jan. 7, 1610, Galileo Gal …
01/08/10
Description On Jan. 7, 1610, Galileo Galilei's improvements to the telescope enabled humanity to see Jupiter's four largest moons for the first time. Io, Europa, Ganymede and Callisto--the so-called Galilean satellites--were seen by the Long Range Reconnaissance Imager on the New Horizons spacecraft during its flyby of Jupiter in late February 2007. The images have been scaled to represent the true relative sizes of the four moons and are arranged in their order from Jupiter. Io is notable for its active volcanism, which New Horizons studied extensively. On the other hand, Europa's smooth, icy surface likely conceals an ocean of liquid water. New Horizons obtained data on Europa's surface composition and imaged subtle surface features, and analysis of these data may provide new information about the ocean and the icy shell that covers it. New Horizons spied Ganymede from 2.2 million miles away. Ganymede, the largest moon in the solar system, has a dirty ice surface cut by fractures and peppered by impact craters. New Horizons' infrared observations may provide insight into the composition of the moon's surface and interior. Scientists are using the infrared spectra New Horizons gathered of Callisto's ancient, cratered surface to calibrate spectral analysis techniques that will help them to understand the surfaces of Pluto and its moon Charon when New Horizons passes them in 2015. Image Credit: NASA/JHU-APL/Southwest Research Institute
Date 01/08/10
Europa, Callisto and Jupiter
One moment in an ancient, or …
12/21/00
Date 12/21/00
Description One moment in an ancient, orbital dance is caught in this color picture taken by NASA's Cassini spacecraft on Dec. 7, 2000, just as two of Jupiter's four major moons, Europa and Callisto, were nearly perfectly aligned with each other and the center of the planet. The distances are deceiving. Europa, seen against Jupiter, is 600,000 kilometers (370,000 miles) above the planet's cloud tops. Callisto, at lower left, is nearly three times that distance from the cloud tops. Europa is a bit smaller than Earth's Moon and has one of the brightest surfaces in the solar system. Callisto is 50 percent bigger -- roughly the size of Saturn's largest satellite, Titan -- and three times darker than Europa. Its brightness had to be enhanced in this picture, relative Europa's and Jupiter's, in order for Callisto to be seen in this image. Europa and Callisto have had very different geologic histories but share some surprising similarities, such as surfaces rich in ice. Callisto has apparently not undergone major internal compositional stratification, but Europa's interior has differentiated into a rocky core and an outer layer of nearly pure ice. Callisto's ancient surface is completely covered by large impact craters: The brightest features seen on Callisto in this image were discovered by the Voyager spacecraft in 1979 to be bright craters, like those on our Moon. In contrast, Europa's young surface is covered by a wild tapestry of ridges, chaotic terrain and only a handful of large craters. Recent data from the magnetometer carried by the Galileo spacecraft, which has been in orbit around Jupiter since 1995, indicate the presence of conducting fluid, most likely salty water, inside both Callisto and Europa. Scientists are eager to discover whether the surface of Saturn's Titan resembles that of Callisto or Europa, or whether it is entirely different, when Cassini finally reaches its destination in 2004. Cassini is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini mission for NASA's Office of Space Science, Washington, D.C. Credit: NASA/JPL/University of Arizona #####
Galilean Moon Interiors
This artist's concept shows …
6/4/98
Date 6/4/98
Description This artist's concept shows cross-sections of the four largest moons of Jupiter, with the interior structures based on the latest information sent back by NASA's Galileo spacecraft. The moons depicted are (clockwise from bottom right) Callisto, Ganymede, Io and Europa. Scientists have modified their concept of Callisto's interior, based on the most recent Galileo findings. Whereas previously they believed that Callisto was completely undifferentiated, with a uniform mixture of rock and ice, scientists now say the interior has some separation of the ice and rock, but not nearly as much as the other three moons. Galileo data indicate that Ganymede is separated into a metallic core, rock mantle, and ice-rich outer shell, while Io has a metallic core and rock mantle, but no ice. Galileo data has also helped scientists refine their model of Europa's structure. They believe Europa has a metallic core surrounded by a rock mantle and a water ice-liquid outer shell. The core may be up to half the size of Europa's radius, with the water ice-liquid shell estimated to be between 80 to 170 kilometers thick (50 to 106 miles), with 100 kilometers (62 miles) considered the most likely thickness. Information on the interior structure of the four moons was obtained by studying radio Doppler data that is gathered when Galileo flies by the satellites. Each moon exerts a gravitational tug, but the tug's strength is determined by how much rock is contained within the moon (the higher the rock content, the stronger the tug). The tug changes the spacecraft's speed and the radio frequency of its signals. Scientists study those changes to determine the rock content and structure of the moon. This material was presented to the American Astronomical Society meeting in San Diego, CA on June 4, 1998. The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is a division of California Institute of Technology (Caltech). This image, along with other images and data received from Galileo, is available on the Galileo mission home page at http://www.jpl.nasa.gov/galileo. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo . #####
Iapetus: A View from the Top
Description Iapetus: A View from the Top
Full Description This oblique view of Saturn's moon Iapetus from high latitude shows how the dark, heavily cratered terrain of Cassini Regio transitions to a bright, icy terrain at high latitudes. In this mosaic of two high resolution images taken during Cassini's New Year's Eve 2004 flyby of Iapetus, the direction toward the north pole is approximately 15 degrees below the horizontal on the right. At the equator terrains are uniformly covered with a dark mantle of material that has a reflectivity of about 4 percent. At latitudes toward the pole of about 40 degrees, the dark deposits become patchy and diffuse as the surface transitions to a much brighter, icy terrain near the pole. The brightest icy materials exhibit visual reflectivity over 60 percent. Superimposed on the bright terrain is a subtle, ghostly pattern of crudely parallel, north-south trending wispy streaks. The streaks, which were discovered during this flyby of Iapetus, are typically a few kilometers wide and sometimes tens of kilometers long. Their appearance and orientation may be connected with the emplacement of dark materials that cover Cassini Regio. The dark materials might represent the gradual accumulation of dark debris falling from space, or alternatively, may represent fallout from plume-style eruptions that may have accompanied the formation of Iapetus's enigmatic equatorial ridge (see PIA 06166). Also seen in this mosaic are conspicuous, north-facing bright crater walls. An example can be seen in the upper left where the bright, 4-kilometer-high (2.5 miles) walls of a 70 kilometer (44 mile) central-peak crater lies. The bright crater walls are often higher in brightness than the corresponding south-facing walls of the same crater. They are vaguely reminiscent of bright north-facing crater walls that were discovered by NASA's Voyager and Galileo spacecraft in craters near the poles of the Jovian satellites Callisto and Ganymede. In the case of the Jovian satellites, cold-trapping of frosts on north-facing slopes and sublimation of ices from south-facing slopes are thought to produce the north-south asymmetries in crater wall brightness. However, the occurrence of some young-appearing craters on Iapetus that have bright north-facing and dark south-facing slopes, and the pattern of streaks near the north pole of Iapetus suggests that another mechanism may be responsible for the crater wall brightness asymmetries on Iapetus. One possibility is that the south-facing slopes may be stained by the same process that emplaced the low brightness coating throughout the region. In this case, the north-pointing scarps might be bright because they face away and are shielded from the putative falling spray of dark materials. Bright south-facing slopes would exist primarily on young craters that have not been exposed to the darkening agent long enough to be stained. The image was obtained in visible light with the Cassini spacecraft narrow angle camera on Dec. 31, 2004, at a distance of, about 123,370 kilometers (76,658 miles) from Iapetus and at a Sun-Iapetus-spacecraft, or phase, angle of 93 degrees. Resolution achieved in the original image was 732 meters (2,401 feet) per pixel. The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging team is based at the Space Science Institute, Boulder, Colo. For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . For images visit the Cassini imaging team home page http://ciclops.org . Credit: NASA/JPL/Space Science Institute
Date January 7, 2005
Description Here on the Gallery page you can find the very latest images, videos and products from the Cassini-Huygens mission to Saturn, including the spectacular launch, spacecraft assembly and the exciting trip to Saturn.
Full Description One moment in an ancient, orbital dance is caught in this color picture taken by NASA's Cassini spacecraft on Dec. 7, 2000, just as two of Jupiter's four major moons, Europa and Callisto, were nearly perfectly aligned with each other and the center of the planet. The distances are deceiving. Europa, seen against Jupiter, is 600,000 kilometers (370,000 miles) above the planet's cloud tops. Callisto, at lower left, is nearly three times that distance from the cloud tops. Europa is a bit smaller than Earth's Moon and has one of the brightest surfaces in the solar system. Callisto is 50 percent bigger -- roughly the size of Saturn's largest satellite, Titan -- and three times darker than Europa. Its brightness had to be enhanced in this picture, relative Europa's and Jupiter's, in order for Callisto to be seen in this image. Europa and Callisto have had very different geologic histories but share some surprising similarities, such as surfaces rich in ice. Callisto has apparently not undergone major internal compositional stratification, but Europa's interior has differentiated into a rocky core and an outer layer of nearly pure ice. Callisto's ancient surface is completely covered by large impact craters: The brightest features seen on Callisto in this image were discovered by the Voyager spacecraft in 1979 to be bright craters, like those on our Moon. In contrast, Europa's young surface is covered by a wild tapestry of ridges, chaotic terrain and only a handful of large craters. Recent data from the magnetometer carried by the Galileo spacecraft, which has been in orbit around Jupiter since 1995, indicate the presence of conducting fluid, most likely salty water, inside both Callisto and Europa. Scientists are eager to discover whether the surface of Saturn's Titan resembles that of Callisto or Europa, or whether it is entirely different, when Cassini finally reaches its destination in 2004. Cassini is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini mission for NASA's Office of Space Science, Washington, D.C. Credit: NASA/JPL/University of Arizona For higher resolution, click here.
Map of Titan in Infrared
Description Mosaic of Titan obtained at the 2.03 micron wavelength
Full Description On Oct. 26, 2004, the Cassini spacecraft flew over Saturn's moon Titan at less than 1,200 kilometers (746 miles) at closest approach. Cassini acquired several infrared images with spatial resolution ranging from a few tens of kilometers (several miles) to 2 kilometers (1.2 miles) per pixel. The visual and infrared mapping spectrometer instrument took images from visible wavelengths to the 5.1 micron wavelength. This figure shows the mosaic obtained at the 2.03 micron wavelength. Observations are centered on the hemisphere of Titan that points away from Saturn. The left (inset) high-resolution image is 30 kilometers (19 miles) per pixel. It shows the site where the European Space Agency's Huygens probe successfully landed on Jan. 14, 2005. The right inset shows a circular feature that scientists think is a volcano, which may be responsible for replenishing Titan's methane atmosphere. Titan¿s diameter is 5,151 kilometers (3,200 miles), which is larger than Jupiter's moon Callisto and smaller than another Jovian moon, Ganymede. Callisto has a diameter of 4,806 kilometers (2,986 miles) and Ganymede is 5,268 kilometers (3,273 miles). The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The visual and infrared mapping spectrometer team is based at the University of Arizona. For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The visual and infrared mapping spectrometer team homepage is at http://wwwvims.lpl.arizona.edu . Credit: NASA/JPL/University of Arizona
Date June 8, 2005
Moons of the Solar System
title Moons of the Solar System
description All the planetary moons in our solar system are shown here at their correct relative size and true color. Their diversity of size and appearance is testament to the unique and fascinating geologic history that each of these bodies has undergone. Two of the moons are larger than the planet Mercury, and eight of them are larger than Pluto. Earth's Moon is the fifth largest of the set, with a diameter of 3476 kilometers (2160 miles). Most of the moons are thought to have formed from a disk of debris left over from formation of the planet they orbit. However Triton, Neptune's largest moon, and several of the smallest moons, including the moons of Mars, are thought to be captured planetesimals that formed elsewhere in the solar system. Earth's Moon is thought to have formed from the debris ejected from a roughly Mars-sized object colliding with the early Earth, perhaps a unique event in the history of the solar system. The moons are organized on the diagram by the planet they orbit (top to bottom with increasing distance from the Sun) and their position relative to the planet (left to right with increasing distance from the planet). Below is a listing of the names of all the moons and the planets they orbit. Most moons are named for mythological characters associated with the character the planet is named for. While most of the planets are named for Roman characters (with the exceptions of Pluto and Uranus), most of the moon have names from Greek mythology. For example, Phobos and Deimos are the sons of Ares, the Greek version of Mars. Jupiter?s moons are all named for lovers and other close associates of Zeus (Jupiter). Saturn?s moons are named for Titans, the race that included Cronos (Saturn), Zeus? father. Neptune?s moons are named for mythological characters associated with water, and Charon was the ferryman of the dead who brought people to Pluto?s realm. By tradition, the discoverer of a moon gets to name it (now subject to approval by the International Astronomical Union). The son of the discoverer of the first two moons of Uranus (Sir William Herschel) decided to name Uranus? moons not for mythological characters, but instead for the king and queen of fairies in Shakespear?s A Midsummer Night?s Dream . This began a tradition whereby all uranian satellites are named for fairy characters in English drama. To read more about the names of the planets and their satellites, go to the U.S. Geological Survey?s nomenclature guide at http://wwwflag.wr.usgs.gov/USGSFlag/Space/nomen/append7.html . *Earth* Moon *Mars * Phobos, Deimos *Jupiter* Metis, Adrastea, Amalthea, Thebe, Io, Europa, Ganymede, Callisto, Leda, Himalia, Lysithea, Elara, Ananke, Carme, Pasiphae, Sinope *Saturn * Pan, Atlas, Prometheus, Pandora, Epimetheus, Janus, Mimas, Enceladus, Tethys, Calypso, Telesto, Dione, Helene, Rhea, Titan, Hyperion, Iapetus, Phoebe *Uranus * Cordelia, Ophelia, Bianca, Cressida, Desdemona, Juliet, Portia, Rosalind, Belinda, Puck, Miranda,, Ariel, Umbriel, Titania, Oberon *Neptune* Naiad, Thalassa, Despina, Galatea, Larissa, Proteus, Triton, Nereid *Pluto * Charon *Image Credit*: Image processing by Tim Parker (Jet Propulsion Laboratory) and Paul Schenk and Robert Herrick (Lunar and Planetary Institute), based on NASA images.
Asgard
title Asgard
date 11.04.1996
description This four-frame mosaic shows the ancient impact structure Asgard on Jupiter's moon Callisto. This image is centered at 300N, 1420W. The Asgard structure is approximately 1700 kilometers across and consists of a bright central zone surrounded by discontinuous rings. The rings are tectonic features with scarps near the central zone and troughs at the outer margin. Several large impacts have smashed into Callisto after the formation of Asgard. The very young, bright-rayed crater Burr is located on the northern part of Asgard. This mosaic has been projected to show a uniform scale between the four images. This image was taken on November 4, 1996, at a distance of 111,891 kilometers by the Solid-State Imaging System onboard the Galileo spacecraft during its third orbit around Jupiter. *Image Credit*: Deutsche Forschungsanstalt fuer Luft-und Raumfahrt (DLR)
Callisto Landslides
title Callisto Landslides
date 12.10.1997
description Galileo images of the surface of Jupiter's moon Callisto have revealed large landslide deposits within two large impact craters seen in the right side of this image. The two landslides are about 3 to 3.5 kilometers in length. They occurred when material from the crater wall failed under the influence of gravity, perhaps aided by seismic disturbances from nearby impacts. These deposits are interesting because they traveled several kilometers from the crater wall in the absence of an atmosphere or other fluids that might have lubricated the flow. This could indicate that the surface material on Callisto is very fine-grained, and perhaps is being "fluffed" by electrostatic forces that allowed the landslide debris to flow extended distances in the absence of an atmosphere. This image was acquired on September 16, 1997, by the Solid-State Imaging System onboard the Galileo spacecraft during it's tenth orbit around Jupiter. North is to the top of the image, with the Sun illuminating the scene from the right. The center of this image is located near 25.30N latitude, 141.30W longitude. The image, which is 55 kilometers by 44 kilometers across, was acquired at a resolution of 100 meters per picture element. *Image Credit*: Arizona State University
Family Portrait of Jupiter's …
title Family Portrait of Jupiter's Great Red Spot and the Galilean Satellites
description This "family portrait," a composite of the Jovian system, includes the edge of Jupiter with its Great Red Spot, and Jupiter's four largest moons, known as the Galilean satellites. From top to bottom, the moons shown are Io, Europa, Ganymede and Callisto. The Great Red Spot, a storm in Jupiter's atmosphere, is at least 300 years old. Winds blow counterclockwise around the Great Red Spot at about 400 kilometers per hour (250 miles per hour). The storm is larger than one Earth diameter from north to south, and more than two Earth diameters from east to west. In this oblique view, the Great Red Spot appears longer in the north-south direction. Europa, the smallest of the four moons, is about the size of Earth's moon, while Ganymede is the largest moon in the solar system. North is at the top of this composite picture in which the massive planet and its largest satellites have all been scaled to a common factor of 15 kilometers (9 miles) per picture element. The Solid State Imaging (CCD) system aboard NASA's Galileo spacecraft obtained the Jupiter, Io and Ganymede images in June 1996, while the Europa images were obtained in September 1996. Because Galileo focuses on high resolution imaging of regional areas on Callisto rather than global coverage, the portrait of Callisto is from the 1979 flyby of NASA's Voyager spacecraft. Launched in October 1989, the spacecraft's mission was to conduct detailed studies of the giant planet, its largest moons and the Jovian magnetic environment. The Jet Propulsion Laboratory, Pasadena, CA, managed the mission for NASA's Office of Space Science, Washington, DC. *Image Credit*: NASA
Callisto Impact Craters
title Callisto Impact Craters
date 12.07.1998
description This composite of Galileo spacecraft images of Jupiter's icy moon Callisto combines data from two orbits showing several types of impact craters. North is to the top of the picture, the Sun illuminates the surface from the east. The global image on the right shows one of the largest impact structures on Callisto, the Asgard multiring structure located near 300N latitude, 1420W longitude. The Asgard structure is approximately 1700 kilometers across and consists of a bright central zone surrounded by discontinuous rings. The rings include degraded ridges near the central zone and troughs at the outer margin, which resulted from deformation of the icy crust following impact. Smaller impacts have smashed into Callisto after the formation of Asgard. The young, bright-rayed crater Burr located on the northern part of Asgard is about 75 kilometers across. Galileo images show a third type of impact crater in this image, a dome crater named Doh, located in the bright central plains of Asgard. Doh (left image) is about 55 kilometers in diameter, while the dome is about 25 kilometers across. Dome craters contain a central mound instead of a bowl-shaped depression or central mountain (peak) typically seen in larger impact craters. This type of crater could represent penetration into a slushy zone beneath the surface of the Asgard impact. The global image on the right was taken on November 4, 1996, at a distance of 111,900 kilometers by the Solid-State Imaging Camera onboard NASA's Galileo spacecraft during its third orbit around Jupiter. The image on the left was obtained at a resolution of 90 meters per picture element on September 16, 1997, during Galileo's tenth orbit when the spacecraft was less than 9500 kilometers from Callisto. *Image Credit*: Arizona State University
Jupiter's Moon Callisto
title Jupiter's Moon Callisto
date 03.06.1979
description Voyager 1 image of Jupiter's moon Callisto from a distance of 350,000 km. Callisto is about 4,800 km in diameter (about the size of Mercury). Features as small as 7 km across can be seen in this image. The large "bulls-eye" at the top of the image is believed to be an impact basin formed early in Callisto's history. The bright center of the basin is about 600 km across and the outer ring is about 2600 km across. (Voyager 1, P-21287) *Image Credit*: NASA
Triple Eclipse
title Triple Eclipse
description At first glance, Jupiter looks like it has a mild case of the measles. Five spots - one colored white, one blue, and three black are scattered across the upper half of the planet. Closer inspection by NASA's Hubble Space Telescope reveals that these spots are actually a rare alignment of three of Jupiter's largest moons - Io, Ganymede, and Callisto - across the planet's face. In this image, the telltale signatures of this alignment are the shadows [the three black circles] cast by the moons. Io's shadow is located just above center and to the left, Ganymede's on the planet's left edge, and Callisto's near the right edge. Only two of the moons, however, are visible in this image. Io is the white circle in the center of the image, and Ganymede is the blue circle at upper right. Callisto is out of the image and to the right. On Earth, we witness a solar eclipse when our Moon's shadow sweeps across our planet's face as it passes in front of our Sun. Jupiter, however, has four moons roughly the same size as Earth's Moon. The shadows of three of them occasionally sweep simultaneously across Jupiter. The image was taken March 28, 2004, with Hubble's Near Infrared Camera and Multi-Object Spectrometer. Seeing three shadows on Jupiter happens only about once or twice a decade. Why is this triple eclipse so unique? Io, Ganymede, and Callisto orbit Jupiter at different rates. Their shadows likewise cross Jupiter's face at different rates. For example, the outermost moon Callisto orbits the slowest of the three satellites. Callisto's shadow moves across the planet once for every 20 shadow crossings of Io. Add the crossing rate of Ganymede's shadow and the possibility of a triple eclipse becomes even more rare. Viewing the triple shadows in 2004 was even more special, because two of the moons were crossing Jupiter's face at the same time as the three shadows. Jupiter appears in pastel colors in this photo because the observation was taken in near-infrared light. Astronomers combined images taken in three near-infrared wavelengths to make this color image. The photo shows sunlight reflected from Jupiter's clouds. In the near infrared, methane gas in Jupiter's atmosphere limits the penetration of sunlight, which causes clouds to appear in different colors depending on their altitude. Studying clouds in near-infrared light is very useful for scientists studying the layers of clouds that make up Jupiter's atmosphere. Yellow colors indicate high clouds, red colors lower clouds, and blue colors even lower clouds in Jupiter's atmosphere. The green color near the poles comes from a thin haze very high in the atmosphere. Ganymede's blue color comes from the absorption of water ice on its surface at longer wavelengths. Io's white color is from light reflected off bright sulfur compounds on the satellite's surface. In viewing this rare alignment, astronomers also tested a new imaging technique. To increase the sharpness of the near-infrared camera images, astronomers, speeded up Hubble's tracking system so that Jupiter traveled through the telescope's field of view much faster than normal. This technique allowed scientists to take rapid-fire snapshots of the planet and its moons. They then combined the images into one single picture to show more details of the planet and its moons. *Image Credit*: NASA, ESA, and E. Karkoschka (University of Arizona)
Capturing Callisto
title Capturing Callisto
date 02.27.2007
description The New Horizons Long Range Reconnaissance Imager (LORRI) captured these two images of Jupiter's outermost large moon, Callisto, as the spacecraft flew past Jupiter in late February. New Horizons' closest approach distance to Jupiter was 2.3 million kilometers (1.4 million miles), not far outside Callisto's orbit, which has a radius of 1.9 million kilometers (1.2 million miles). However, Callisto happened to be on the opposite side of Jupiter during the spacecraft's pass through the Jupiter system, so these images, taken from 4.7 million kilometers (3.0 million miles) and 4.2 million kilometers (2.6 million miles) away, are the closest of Callisto that New Horizons obtained. Callisto's ancient, crater-scarred surface makes it very different from its three more active sibling satellites, Io, Europa and Ganymede. Callisto, 4,800 kilometers (3000 miles) in diameter, displays no large-scale geological features other than impact craters, and every bright spot in these images is a crater. The largest impact feature on Callisto, the huge basin Valhalla, is visible as a bright patch at the 10 o'clock position. The craters are bright because they have excavated material relatively rich in water ice from beneath the dark, dusty material that coats most of the surface. The two images show essentially the same side of Callisto - the side that faces Jupiter - under different illumination conditions. The images accompanied scans of Callisto's infrared spectrum with New Horizons' Linear Etalon Imaging Spectral Array (LEISA). The New Horizons science team designed these scans to study how the infrared spectrum of Callisto's water ice changes as lighting and viewing conditions change, and as the ice cools through Callisto's late afternoon. The infrared spectrum of water ice depends slightly on its temperature, and a goal of New Horizons when it reaches the Pluto system (in 2015) is to use the water ice features in the spectrum of Pluto's moon Charon, and perhaps on Pluto itself, to measure surface temperature. Callisto provided an ideal opportunity to test this technique on a much better-known body. The left image, taken at 05:03 Universal Time on February 27, 2007, is centered at 5 degrees south, 5 degrees west, and has a solar phase angle of 46 degrees. The right image was taken at 03:25 Universal Time on February 28, 2007. It is centered at 4 degrees south, 356 degrees west, and has a solar phase angle of 76 degrees. Released: April 5, 2007 Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute
Image of Pele erupting on Io
Name Image of Pele erupting on Io
Jupiter System Montage
Title Jupiter System Montage
Full Description Jupiter and its four planet-size moons, called the Galilean satellites, were photographed in early March 1979 by Voyager 1 and assembled into this collage. They are not to scale but are in their relative positions. Startling new discoveries on the Galilean moons and the planet Jupiter made by Voyager l factored into a new mission design for Voyager 2. Reddish Io (upper left) is nearest Jupiter, then Europa (center), Ganymede and Callisto (lower right). Nine other much smaller satellites circle Jupiter, one inside Io's orbit and the other millions of miles from the planet. Not visible is Jupiter's faint ring of particles, seen for the first time by Voyager 1. The Voyager Project is managed for NASA's Office of Space Science by Jet Propulsion Laboratory, California Institute of Technology.
Date 06/22/1979
NASA Center Jet Propulsion Laboratory
Voyager 1 View of Callisto
Title Voyager 1 View of Callisto
Full Description Voyager 1 took this picture of Callisto during Voyager's approach to Jupiter's outer large satellite in 1979. Both Galileo and Marius discovered Callisto in 1610. In Greek mythology, Callisto was a nymph loved by Zeus and thus hated by Hera. Hera turned her into a bear, which Zeus placed in the heavens as the constellation Ursa Major. Voyager was 350,000 kilometers from Callisto and took this picture that shows features about seven kilometers wide across the surface. Callisto is a little smaller than Ganymede (Callisto is about the size of Mercury) and it seems that it is composed of a mixture of ice and rock (about 40 percent ice and 60 percent rock and iron). The darker color of Callisto (about half as reflective as Ganymede but still twice as bright as the Moon) implies that the upper surface is "dirty ice" or water- rich rock frozen on Callisto's cold surface (approximately -243 Fahrenheit degrees at the equator). Callisto's atmosphere is mostly carbon dioxide. Far more craters appear on the surface of Callisto than on the surface of Ganymede, leading scientists to believe that Callisto is the oldest of the Galilean satellites. Callisto could date back as far as four billion years ago and has remained relatively unchanged in the history of space.
Date 03/06/1979
NASA Center Jet Propulsion Laboratory
Hubble Photo Gallery of Jupi …
Title Hubble Photo Gallery of Jupiter's Galilean Satellites
A79-7017
Photographer : JPL Range : 7 …
2/28/79
Description Photographer : JPL Range : 7 million kilometers (5 million miles) Callisto is the outermost Galilean satellite of Jupiter and the darkest of the four, but still twice as bright as Earth's Moon. Mottled appearance from bright and dark patches, bright ones look like rayed or brite craters on our Moon. This face of Callisto is always turned toward Jupiter. Photo taken through violet filter.
Date 2/28/79
A79-7020
Photographer : JPL Range : 7 …
2/28/79
Description Photographer : JPL Range : 7 million kilometers (5 million miles) Callisto is Jupiter's outermost Galilean satellites and darkest of the four(but almost twice as bright as Earth's Moon). Mottled appearance from bright and dark patches. Bright spots seem like rayed or bright halved craters seen on our Moon. This face is always turned toward Jupiter. Photo taken through violet filter. Ganymede is slightly larger than Mercury but much less dense (twice the density of water). Its surface brightness is 4 times of Earth's Moon. Mare regions (dark features) are like the Moon's but have twice the brightness, and believed to be unlikely of rock or lava as the Moon's are. It's north pole seems covered with brighter material and may be water frost. Scattered brighter spots may be related to impact craters or source of fresh ice.
Date 2/28/79
A79-7027
Photographer: JPL This photo …
2/28/79
Description Photographer: JPL This photo of Callisto, outermost of Jupiter's four Galilean satellites, was taken a few minutes after midnight (PST) Feb. 25 by Voyager 1. The distance to Callisto was 8,023,000 kilometers (4.98 million miles). The hemisphere in this picture shows a fairly uniform surface dotted with brighter spots that are up to several hundred kilometers across. Scientists believe the spots may be impact craters but higher-resolution photos will be necessary before the features can be interpreted. Callisto is about the same size as the planet Mercury--about 5,000 kilometers (3,000 miles) in diameter. Callisto is less massive than Mercury, however, giving it a density less than twice that of water. Scientists believe Callisto, therefore, is composed of a mixture of rock and ice (up to about 50 percent by weight). Its surface is darker than those of the other Galilean satellites, but is still about twice as bright as Earth's Moon. This black-and-white photo was taken through a violet filter. Jet Propulsion Laboratory manages and controls the Voyager project for NASA's Office of Space Science. (JPL ref. No. P-21149)
Date 2/28/79
A79-7075
Photographer: JPL P-21740 BW …
7/7/79
Description Photographer: JPL P-21740 BW Range: 2,318,000 kilometers (1,438,000 miles) This picture of Callisto taken by Voyager 2 shows the moon covered with bright spots which are metoerite impact craters--a fact originally discovered from the high resolution pictures taken by Voyager 1. Scientists believe that heavily cratered terrains like these on Callisto are indicative of ancient planetary surfaces. Voyager 2 mapped the side of Callisto not seen by Voyager 1. The obsure dark streaks in this area may be fault zones, but higher resolution pictures are needed for identification.
Date 7/7/79
A79-7093
Photographer : JPL Range : 2 …
7/9/79
Description Photographer : JPL Range : 225,000 kilometers (140,625 miles) This image of the Jovian moon Europa was taken by Voyager 2 along the evening terminator, which best shows the surface topography of complex narrow ridges, seen as curved bright streaks, 5 to 10 kilometers wide, and typically 100 kilometers in length. The area shown is about 600 by 800 kilometers, and the smallest features visible are about 4 kilometers in size. Also visable are dark bands, more diffused in character, 20 to 40 kilometers wide and hundreds to thousands of kilometers in length. A few features are suggestive of impact craters but are rare, indication that the surface thought to be dominantly ice is still active, perhaps warmed by tidal heating like Io. The larger icy satellites, Callisto and Ganymede, are evidently colder with much more rigid crusts and ancient impact craters. The complex intersection of dark markings and bright ridges suggest that the surface has been fractured and material from beneath has welled up to fill the cracks.
Date 7/9/79
AC79-0164-2
Date: Feb 5, 1979 Photo by V …
2/5/79
Description Date: Feb 5, 1979 Photo by Voyager 1 (JPL) Jupiter, its Great Red Spot and three of its four largest satellites are visible in this photo taken Feb 5, 1979 by Voyager 1. The spacecraft was 28.4 million kilomters (17.5 million miles) from the planet at the time. The inner-most large satellite, Io, can be seen against Jupiter's disk. Io is distinguished by its bright, brown-yellow surface. To the right of Jupiter is the satellite Europa, also very bright but with fainter surface markings. The darkest satellite, Callisto (still nearly twice as bright as Earth's Moon), is barely visible at the bottom left of the picture. Callisto shows a bright patch in its northern hemisphere. All tThree orbit Jupiter in the equatorial plane, and appear in their present position because Voyageris above the plane. All three satellites show the same face to Jupiter always -- just as Earth's Moon always shows us the same face. In this photo we see the sides of the satellites that always face away from the planet. Jupiter's colorfully banded atmosphere displays complex patterns highlighted by the Great Red Spot, a large, circulating atmospheric disturbance. This photo was assembled from three black and white negatives by the Image Processing Lab at Jet Propulsion Laboratory. JPL manages and controls the Voyage Project for NASA's Office of Space Science. (ref: P-21083)
Date 2/5/79
AC79-7002
Photographer : JPL Callisto …
2/28/79
Description Photographer : JPL Callisto , The outermost Galilean Satellite , or Moon , of Jupiter, as taken by Voyager I . Range : About 7 Million km (5 Million miles) . Callisto, the darkest of the Galilean Satellites, still nearly twice as bright as the Earth's Moon, is seen here from the face that always faces Jupiter. All of the Galilean Satellites always show the same face to Jupiter, as the Earth's moon does to Earth. The Surface shows a mottled appearance of bright and dark patches. The former reminds scientists of rayed or bright haloed craters, similiar to those seen on earth's Moon. This color photo is assembled from 3 black and wite images taken though violet, orange, & green filters
Date 2/28/79
AC79-7075
Photographer: JPL P-21740 C …
7/7/79
Description Photographer: JPL P-21740 C Range: 2,318,000 kilometers (1,438,000 miles) This picture of Callisto taken by Voyager 2 shows the moon covered with bright spots which are metoerite impact craters--a fact originally discovered from the high resolution pictures taken by Voyager 1. Scientists believe that heavily cratered terrains like these on Callisto are indicative of ancient planetary surfaces. Voyager 2 mapped the side of Callisto not seen by Voyager 1. The obsure dark streaks in this area may be fault zones, but higher resolution pictures are needed for identification.
Date 7/7/79
Pele Erupting on Lo
Name of Image Pele Erupting on Lo
Date of Image 2001-01-01
Full Description This image of Jupiter's moon, lo, was taken by the Chandra X-Ray Observatory (CXO). Shown here is the most extreme example of the effect of tidal forces as Lo is being pulled by massive Jupiter on one side and by the outer moons Europa, Callisto, and Ganymede on the other. The opposing tidal forces alternately squeeze and stretch its interior, causing the solid surface to rise and fall by about 100 meters. The enormous amount of heat and pressure generated by the resulting friction creates colossal volcanoes and fractures on the surface of this moon.
Asgard Scarp Mosaic
Title Asgard Scarp Mosaic
Description Low-resolution color data were combined with a higher resolution mosaic to produce this infrared composite image of a pair of ancient multi-ringed impact basins on Jupiter's moon, Callisto. The region imaged is on the leading hemisphere of Callisto near 26 degrees north, 142 degrees west, and is almost 1,400 kilometers (860 miles) across. North is toward the top of the picture and the Sun illuminates the surface from the east. Dominating the scene is the impact structure, Asgard, centered on the smooth, bright region near the middle of the picture and surrounded by concentric rings up to 1,700 kilometers (about 1,050 miles) in diameter. A second ringed structure with a diameter of about 500 kilometers (310 miles) can be seen to the north of Asgard, partially obscured by the more recent, bright-rayed crater, Burr. The icy materials excavated by the younger craters contrast sharply with the darker and redder coatings on older surfaces of Callisto. Launched in October 1989, Galileo entered orbit around Jupiter on Dec. 7, 1995. The spacecraft's mission is to conduct detailed studies of the giant planet, its largest moons and the Jovian magnetic environment. The Jet Propulsion Laboratory, Pasadena, CA, manages the mission for NASA's Office of Space Science, Washington, DC. This image and other images and data received from Galileo are posted on the World Wide Web Galileo mission home page at http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo.
Date 02.10.1997
Oberon at Voyager Closest Ap …
Title Oberon at Voyager Closest Approach
Description This Voyager 2 picture of Oberon is the best the spacecraft acquired of Uranus' outermost moon. The picture was taken shortly after 3:30 a.m. PST on Jan. 24, 1986, from a distance of 660,000 kilometers (410,000 miles). The color was reconstructed from images taken through the narrow-angle camera's violet, clear and green filters. The picture shows features as small as 12 km (7 mi) on the moon's surface. Clearly visible are several large impact craters in Oberon's icy surface surrounded by bright rays similar to those seen on Jupiter's moon Callisto. Quite prominent near the center of Oberon's disk is a large crater with a bright central peak and a floor partially covered with very dark material. This may be icy, carbon-rich material erupted onto the crater floor sometime after the crater formed. Another striking topographic feature is a large mountain, about 6 km (4 mi) high, peeking out on the lower left limb. The Voyager project is managed for NASA by the Jet Propulsion Laboratory.
Date 01.25.1986
Callisto Close-up with Jagge …
Title Callisto Close-up with Jagged Hills
Description The highest-resolution views ever obtained of any of Jupiter's moons, taken by NASA's Galileo spacecraft in May 2001, reveal numerous bright, sharp knobs covering a portion of Jupiter's moon Callisto. The knobby terrain seen throughout the top inset is unlike any seen before on Jupiter's moons. The spires are very icy but also contain some darker dust. As the ice erodes, the dark material apparently slides down and collects in low-lying areas. Over time, as the surface continues to erode, the icy knobs will likely disappear, producing a scene similar to the bottom inset. The number of impact craters in the bottom image indicates that erosion has essentially ceased in the dark plains shown in that image, allowing impact craters to persist and accumulate. The knobs are about 80 to 100 meters (260 to 330 feet) tall, and they may consist of material thrown outward from a major impact billions of years ago. The areas captured in the images lie south of Callisto's large Asgard impact basin. The smallest features discernable in the images are about 3 meters (10 feet) across. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Galileo mission for NASA's Office of Space Science, Washington, D.C. Additional information about the spacecraft and its discoveries is available on the Galileo home page athttp://galileo.jpl.nasa.gov [ http://galileo.jpl.nasa.gov ].
Date 08.22.2001
Callisto Crater Chain at Hig …
Title Callisto Crater Chain at High Resolution Shown in Context
Description A portion of a chain of impact craters on Jupiter's moon Callisto is seen in this image taken by the Galileo spacecraft on November 4, 1996. This crater chain on Callisto is believed to result from the impact of a split object, similar to the fragments of Comet Shoemaker-Levy 9 which smashed into Jupiter's atmosphere in July of 1994. This high-resolution view, taken by Galileo's solid state imaging television camera during its third orbit around Jupiter, is of Callisto's northern hemisphere at 35 degrees north, 46 degrees west, and covers an area of about eight miles (13 kilometers) across. The smallest visible crater is about 140 yards (130 meters) across. The image was taken at a range of 974 miles (1,567 kilometers). On a global scale, Callisto is heavily cratered, indicating the great age of its surface. At the scale of this image, it was anticipated that the surface would be heavily cratered as well, however, there is a surprising lack of small craters, suggesting that one or more processes have obliterated these and other small-scale features. For example, downslope movement of ice-rich debris could bury small craters. The bright slopes visible in this picture represent places where downslope movement has taken place, exposing fresh ice surfaces. The Jet Propulsion Laboratory manages the Galileo mission for NASA's Office of Space Science, Washington, DC. This image and other images and data received from Galileo are posted on the World Wide Web Galileo mission home page at http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http:// www.jpl.nasa.gov/galileo/sepo.
Date 02.28.1997
Rhea - icy cratered surface
Title Rhea - icy cratered surface
Description The icy, cratered surface of Saturn's moon Rhea is seen in this image taken by Voyager 1 on Nov. 12, 1980, at a range of 85,000 kilometers (52,800 miles) as the spacecraft passed over the satellite's north pole. The heavily cratered surface attests to the satellite's ancient age. The largest craters, 50 to 100 kilometers (30 to 60 miles) across and several kilometers deep, are freshly preserved in Rhea's icy crust. The craters and landscape resemble those on the Moon and Mercury, and are unlike the flattened crater forms that have collapsed in the soft icy crusts of the Jovian moons Callisto, Ganymede and Europa. Scientists believe that Rhea (which is just 1,600 kilometers or 995 miles in diameter, compared to the 5,500-kilometer or 3,400-mile diameter of Ganymede) froze and became rigid, behaving like a rocky surface, very early in its history. The Voyager project is managed for NASA by the Jet Propulsion Laboratory, Pasadena, Calif.
Date 02.10.1981
Global Callisto in Color
Title Global Callisto in Color
Description Bright scars on a darker surface testify to a long history of impacts on Jupiter's moon Callisto in this image of Callisto from NASA's Galileo spacecraft. The picture, taken in May 2001, is the only complete global color image of Callisto obtained by Galileo, which has been orbiting Jupiter since December 1995. Of Jupiter's four largest moons, Callisto orbits farthest from the giant planet. Callisto's surface is uniformly cratered but is not uniform in color or brightness. Scientists believe the brighter areas are mainly ice and the darker areas are highly eroded, ice-poor material. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Galileo mission for NASA's Office of Space Science, Washington, D.C. Additional information about the spacecraft and its discoveries is available on the Galileo home page athttp://galileo.jpl.nasa.gov [ http://galileo.jpl.nasa.gov ].
Date 08.22.2001
The Galilean Satellites
Title The Galilean Satellites
Description This composite includes the four largest moons of Jupiter which are known as the Galilean satellites. From left to right, the moons shown are Ganymede, Callisto, Io, and Europa. The Galilean satellites were first seen by the Italian astronomer Galileo Galilei in 1610. In order of increasing distance from Jupiter, Io is closest, followed by Europa, Ganymede, and Callisto. The order of these satellites from the planet Jupiter helps to explain some of the visible differences among the moons. Io is subject to the strongest tidal stresses from the massive planet. These stresses generate internal heating which is released at the surface and makes Io the most volcanically active body in our solar system. Europa appears to be strongly differentiated with a rock/iron core, an ice layer at its surface, and the potential for local or global zones of water between these layers. Tectonic resurfacing brightens terrain on the less active and partially differentiated moon Ganymede. Callisto, furthest from Jupiter, appears heavily cratered at low resolutions and shows no evidence of internal activity. North is to the top of this composite picture in which these satellites have all been scaled to a common factor of 10 kilometers (6 miles) per picture element. The Solid State Imaging (CCD) system aboard NASA's Galileo spacecraft obtained the Io and Ganymede images in June 1996, while the Europa images were obtained in September 1996. Because Galileo focuses on high resolution imaging of regional areas on Callisto rather than global coverage, the portrait of Callisto is from the 1979 flyby of NASA's Voyager spacecraft. Launched in October 1989, the spacecraft's mission is to conduct detailed studies of the giant planet, its largest moons and the Jovian magnetic environment. The Jet Propulsion Laboratory, Pasadena, CA, manages the mission for NASA's Office of Space Science, Washington, DC. This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at: http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at: http:/ /www.jpl.nasa.gov/galileo/sepo.
Date 05.30.1997
Jupiter's Inner Satellites a …
Title Jupiter's Inner Satellites and Ring Components
Description This schematic cut-away view of the components of Jupiter's ring system shows the geometry of the rings in relation to Jupiter and to the small inner satellites, which are the source of the dust which forms the rings. [figure removed for brevity, see original site] *The Formation of Jupiter's Ring System* The innermost and thickest ring, shown in gray shading, is the halo that ends at the main ring. The thin, narrow main ring, shown with red shading, is bounded by the 16- kilometer-wide (10-miles) satellite Adrastea and shows a marked decrease in brightness near the orbit of Jupiter's innermost moon, Metis. It is composed of fine particles knocked off Adrastea and Metis. Although the orbits of Adrastea and Metis are about 1,000 kilometers (about 600 miles) apart, that separation is not depicted in this drawing. Impacts by small meteoroids (fragments of asteroids and comets) into these small, low-gravity satellites feed material into the rings. Thebe and Amalthea, the next two satellites in increasing distance from Jupiter, supply dust which forms the thicker, disk-like "gossamer" rings. The gossamer rings, depicted with yellow and green shading, are thicker because the source satellites orbit Jupiter on inclined paths [figure removed for brevity, see original site] *Satellite Interactions with Jupiter's Ring System* These small satellites all orbit closer to Jupiter than the four largest Galilean satellites, Io, Europa, Ganymede and Callisto, which were discovered nearly 400 years ago. The orbital distances of the moons are drawn relative to the size of Jupiter.*Jupiter's Main Ring and Inner Satellites*Side view of system:Overhead view of system: [figure removed for brevity, see original site] [figure removed for brevity, see original site] The Jupiter image was created from a map based on data obtained by the Hubble Space Telescope. JPL manages the Galileo mission for NASA's Office of Space Science, Washington, DC. The images are posted on the Internet athttp://photojournal.jpl.nasa.gov/ [ http://photojournal.jpl.nasa.gov/ ]and athttp://galileo.jpl.nasa.gov [ http://galileo.jpl.nasa.gov ]. Background information and educational context for the images can be found at:http://www.jpl.nasa.gov/galileo/sepo [ http://www.jpl.nasa.gov/galileo/sepo ].
Date 09.15.1998
Callisto From 8,023,000 kilo …
PIA01510
Jupiter
Imaging Science Subsystem - …
Title Callisto From 8,023,000 kilometers
Original Caption Released with Image This photo of Callisto, outermost of Jupiter's four Galilean satellites, was taken a few minutes after midnight (PST) Feb. 26 by Voyager 1. The distance to Callisto was 8,023,000 kilometers (4.98 million miles). The hemisphere in this picture shows a fairly uniform surface dotted with brighter spots that are up to several hundred kilometers across. Scientists believe the spots may be impact craters but higher-resolution photos will be necessary before the features can be interpreted. Callisto is about the same size as the planet Mercury -- about 5,000 kilometers (3,000 miles) in diameter. Callisto is much less massive than Mercury, however, giving density less than twice that of water. Scientists believe Callisto, therefore, is composed of a mixture of rock and ice (up to about 50 percent by weight). Its surface is darker than those of the other Galilean satellites, but is still about twice as bright as Earth's Moon. This color photo was assembled from three black and white images in the Image Processing Lab at Jet Propulsion Laboratory. JPL manages and controls the Voyager project for NASA's Office of Space Science.
Callisto From 7,000,000 kilo …
PIA01511
Jupiter
Imaging Science Subsystem - …
Title Callisto From 7,000,000 kilometers
Original Caption Released with Image This Voyager 1 picture of Callisto, the outermost Galilean satellite, was taken February 28 from a distance of about 5 million miles (7 million kilometers). Callisto is the darkest of the Galilean satellites but is still nearly twice as bright as the Earth's Moon. The surface shows a mottled appearance consisting of bright and dark patches. The bright spots remind scientists of rayed or bright haloed craters, similar to those seen on the Earth's Moon. The Galilean satellites all show the same face to Jupiter -- just as the Earth's Moon always shows us the same face. In this photo we see the face of Callisto that always faces Jupiter. JPL manages and controls the Voyager Project for NASA's Office of Space Science.
Callisto False Color
PIA00457
Jupiter
Imaging Science Subsystem - …
Title Callisto False Color
Original Caption Released with Image This false color picture of Callisto was taken by Voyager 2 on July 7, 1979 at a range of 1,094,666 kilometers (677,000 miles) and is centered on 11 degrees N and 171 degrees W. This rendition uses an ultraviolet image for the blue component. Because the surface displays regional contrast in UV, variations in surface materials are apparent. Notice in particular the dark blue haloes which surround bright craters in the eastern hemisphere. The surface of Callisto is the most heavily cratered of the Galilean satellites and resembles ancient heavily cratered terrains on the moon, Mercury and Mars. The bright areas are ejecta thrown out by relatively young impact craters. A large ringed structure, probably an impact basin, is shown in the upper left part of the picture. The color version of this picture was constructed by compositing black and white images taken through the ultraviolet, clear and orange filters.
Textured Terrain in Callisto …
PIA01629
Jupiter
Title Textured Terrain in Callisto's Asgard Basin
Original Caption Released with Image This fascinating region of Jupiter's icy moon, Callisto, shows the transition from the inner part of an enormous impact basin, Asgard, to the outer "surrounding plains." Small, bright, fine textured, closely spaced bumps appear throughout the inner part of the basin (top of image) and create a more fine textured appearance than that seen on many of the other inter-crater plains on Callisto. At low resolution, these icy bumps make Asgard's center brighter than the surrounding terrain. What caused the bumps to form is still unknown, but they are associated clearly with the impact that formed Asgard. The ridge that cuts diagonally across the lower left corner is one of many giant concentric rings that extend for hundreds of kilometers outside Asgard's center. Exterior to the ring (lower left corner), Callisto's surface changes significantly. Still peppered with craters, the number of icy bumps decreases while their average size increases. The fine texture is not as visible in the middle of the image. One explanation is that material from raised features (such as the ridge) may slide down slope and cover small scale features. Such images of Callisto help us understand the dynamics of giant impacts into icy surfaces, and how the large structures change with time. North is to the top of the picture. The image, centered at 27.1 degrees north latitude and 142.3 degrees west longitude, covers an area approximately 80 kilometers (50 miles) by 90 kilometers (55 miles). The resolution is about 90 meters (295 feet) per picture element. The image was taken on September 17th, 1997 at a range of 9200 kilometers (5700 miles) by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft during its tenth orbit of Jupiter. The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov [ http://galileo.jpl.nasa.gov ] . Background information and educational context for the images can be found at URL http://www.jpl.nasa.gov/galileo/sepo [ http://www.jpl.nasa.gov/galileo/sepo ].
Asgard Multi-Ring Structure …
PIA01634
Jupiter
Solid-State Imaging
Title Asgard Multi-Ring Structure on Callisto
Original Caption Released with Image This mosaic shows the Asgard multi-ring structure on Callisto, Jupiter's second largest icy moon. The Asgard structure [ http://photojournal.jpl.nasa.gov/catalog/PIA00517 ], centered near 30 degrees north latitude, 142 degrees west longitude, is approximately 1700 km across (1,056 miles) and consists of a bright central zone surrounded by discontinuous rings. The rings are fractures that formed when Callisto's surface was struck by a large comet or asteroid. Previous analysis of Asgard identified three major zones: 1) interior bright plains in the center, 2) a zone of inward facing cliffs and, 3) a zone of discontinuous concentric troughs. The mosaic combines high resolution data of 88 meters per picture element (pixel) taken on the tenth orbit of the Galileo spacecraft around Jupiter in September 1997, with low resolution data of 1.1 kilometers (km) per pixel obtained on the third orbit in November 1996. The improved resolution of images obtained by the Solid State Imaging (SSI) system on board NASA's Galileo spacecraft allows for new insights into the Asgard multi-ring system. Galileo images show that the bright central plains includes a young dome crater, named Doh, located on its southwestern margin (at the top of the high resolution strip). Doh is about 50 km (30 miles) in diameter. Dome craters contain a central mound instead of a bowl shaped depression or the central mountain typically seen in craters. The inner rings of Asgard appear to be degraded ridges in the high resolution data, rather than inward-facing cliffs or scarps as previously interpreted from lower resolution images. In the outermost rings, dark non-ice material that slid down the walls of the troughs has made their floors darker than the surrounding cratered plains. North is to the top of the picture. The high resolution images were obtained with the clear filter of the Solid State Imaging (SSI) system when NASA's Galileo spacecraft was less than 9,500 kilometers from Callisto. There appears to be a diffuse darker stripe, beginning near the middle and continuing down the strip of higher resolution frames. This darkening is due to the processing used to place the higher resolution frames into the background context. The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission or NASA's Office of Space Science, Washington, DC. This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov [ http://galileo.jpl.nasa.gov ]. Background information and educational context for the images can be found at URL http://www.jpl.nasa.gov/galileo/sepo [ http://www.jpl.nasa.gov/galileo/sepo ].
Asgard impact structure on C …
PIA00517
Jupiter
Solid-State Imaging
Title Asgard impact structure on Callisto
Original Caption Released with Image This four-frame mosaic shows the ancient impact structure Asgard on Jupiter's moon Callisto. This image is centered at 30 degrees north, 142 degrees west. The Asgard structure is approximately 1700 km across (1,056 mi) and consists of a bright central zone surrounded by discontinuous rings. The rings are tectonic features with scarps near the central zone and troughs at the outer margin. Several large impacts have smashed into Callisto after the formation of Asgard. The very young, bright-rayed crater Burr is located on the northern part of Asgard. This mosaic has been projected to show a uniform scale between the four mosaiced images. The image was processed by Deutsche Forschungsanstalt fuer Luftund Raumfahrt e.V., Berlin, Germany. This image was taken on November 4, 1996, at a distance of 111,891 kilometers (69,070 miles) by the solid state imaging television camera onboard the Galileo spacecraft during its third orbit around Jupiter. The Galileo mission is managed by the Jet Propulsion Laboratory for NASA's Office of Space Science, Washington, D.C. This image and other images and data received from Galileo are posted on the Galileo mission home page on the World Wide Web at http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo
Crater Tindr on Callisto - a …
PIA01657
Jupiter
Solid-State Imaging
Title Crater Tindr on Callisto - an oblique impact?
Original Caption Released with Image This single-frame image shows crater Tindr on Jupiter's satellite Callisto, the moon with the oldest surface of the four so-called "Galilean" satellites (of which Callisto is also most distant from Jupiter). The diameter of this impact feature is about 70 km (43.5 miles). Tindris situated close to Callisto's equator at a longitude of about 5 degrees East. The image was obtained in September 1997 with the Solid State Imaging (SSI) system onboard NASA's Galileo spacecraft, which has been orbiting the Solar System's largest planet since December 1995. Shadows are long and accentuate morphology on the surface, because the image was taken under low sun illumination. The image was captured from a distance of about 40,000 km(25,000 miles) during Galileo's 10th orbit around Jupiter. The resolution is about 390 m/pixel, the smallest features that are still discernible are about 780 m across. The sun illuminates the scene from the left. North is pointing towards the top of the image. The image covers an area approximately 150 x 150 km. Tindr is slightly irregular in shape. This could be the consequence of an oblique impact. Along its eastern and southeastern part, the rim appears degraded, only isolated hills or hill chains are still visible. The floor shows numerous irregular pits, features that are found in some other Callistoan craters and also in Callisto's dark cratered plains. These features are believed to be caused by sublimation of subsurface volatiles. Subradial streaks outside the crater rim are due to impact debris creating secondary craters some distance away from Tindr. Continuous ejecta covers several older craters, especially in the northeastern part of the scene. The Tindr ejecta merge into surrounding cratered plains without a distinct morphologic or albedo boundary. Apparently the dark material blanketing Callisto's surface globally was emplaced after Tindr had formed. Absolute ages derived from measured crater densities are model-dependent. In one crater chronology model, based on impacts dominated by asteroids, Tindr may be an old feature, about 3.9 billion years old, pointing back in time into a period of more intense bombardment than today. In another model, based on impacts preferentially by comets with a more or less constant impact rate, Tindr can be much younger, about 1 billion years old. The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov [ http://galileo.jpl.nasa.gov ]. Background information and educational context for the images can be found at URL http://www.jpl.nasa.gov/galileo/sepo [ http://www.jpl.nasa.gov/galileo/sepo ].
A Chain of Impact Craters on …
PIA00514
Jupiter
Solid-State Imaging
Title A Chain of Impact Craters on Callisto
Original Caption Released with Image A portion of a chain of impact craters on Jupiter's moon Callisto is seen in this image taken by the Galileo spacecraft on November 4, 1996. This crater chain on Callisto is believed to result from the impact of a split object, similar to the fragments of Comet Shoemaker-Levy 9 which smashed into Jupiter's atmosphere in July of 1994. This high-resolution view, taken by Galileo's solid state imaging television camera during its third orbit around Jupiter, is of Callisto's northern hemisphere at 35 degrees north, 46 degrees west, and covers an area of about eight miles (13 kilometers) across. The smallest visible crater is about 140 yards (130 meters) across. The image was taken at a range of 974 miles (1,567 kilometers). On a global scale, Callisto is heavily cratered, indicating the great age of its surface. At the scale of this image, it was anticipated that the surface would be heavily cratered as well, however, there is a surprising lack of small craters, suggesting that one or more processes have obliterated these and other small-scale features. For example, downslope movement of ice-rich debris could bury small craters. The bright slopes visible in this picture represent places where downslope movement has taken place, exposing fresh ice surfaces. The Galileo mission is managed by the Jet Propulsion Laboratory for NASA's Office of Space Science, Washington, D.C. This image and other images and data received from Galileo are posted on the Galileo mission home page on the World Wide Web at http://galileo.jpl.nasa.gov/ [ http://galileo.jpl.nasa.gov/ ]. Background information and educational context for the images can be found at http://www2.jpl.nasa.gov/galileo/sepo/ [ http://www2.jpl.nasa.gov/galileo/sepo/ ].
Callisto's Valhalla impact s …
PIA00516
Jupiter
Solid-State Imaging
Title Callisto's Valhalla impact structure
Original Caption Released with Image A portion of the central zone of the large impact structure Valhalla on Jupiter's moon Callisto was imaged by the Galileo spacecraft on November 4, 1996. The area shown here is centered at 16 degrees north, 55 degrees west and is about seven miles (11 kilometers) across. This is the highest resolution picture ever taken of Callisto and shows features as small as 200 feet (60 meters) across. The formation of Valhalla occurred early in Callisto's history, however, the central zone shown here is probably younger than Valhalla's surrounding structure. This newly acquired picture shows some small craters, although they have been softened or modified by downslope movement of debris, revealing bright ice-rich surfaces. In contrast to other areas on Callisto, most of the very smallest craters appear to have been completely obliterated. This image was taken by the solid state imaging television camera onboard the Galileo spacecraft during its third orbit around Jupiter, at a distance of 757 miles (1,219 kilometers). The Galileo mission is managed by the Jet Propulsion Laboratory for NASA's Office of Space Science, Washington, D.C. This image and other images and data received from Galileo are posted on the Galileo mission home page on the World Wide Web at http://galileo.jpl.nasa.gov/ [ http://galileo.jpl.nasa.gov/ ]. Background information and educational context for the images can be found at http://www2.jpl.nasa.gov/galileo/sepo/ [ http://www2.jpl.nasa.gov/galileo/sepo/ ].
Europa, Ganymede, and Callis …
PIA01656
Jupiter
Solid-State Imaging
Title Europa, Ganymede, and Callisto: Surface comparison at high spatial resolution
Original Caption Released with Image Ganymede's youngest large craters would have been created only about one billion years ago. Europa's surface in this model should be very young, with this satellite being geologically quite active even today. The images were taken by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft. They were processed by the Institute of Planetary Exploration of the German Aerospace Center (DLR) in Berlin, Germany, and scaled to a size of 150 meters per pixel (m/pixel). North is up in all images. The spatial resolution of the original data was 180 m/pixel for Europa and Ganymede and 90 m/pixel for Callisto. The Europa image was taken during Galileo's 6th orbit, the Ganymede image during the 7th, and the Callisto image during the 10th orbit. The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov [ http://galileo.jpl.nasa.gov ]. Background information and educational context for the images can be found at URL http://www.jpl.nasa.gov/galileo/sepo [ http://www.jpl.nasa.gov/galileo/sepo ]., These images show a comparison of the surfaces of the three icy Galilean satellites, Europa, Ganymede, and Callisto, scaled to a common resolution of 150 meters per picture element (pixel). Despite the similar distance of 0.8 billion kilometers to the sun, their surfaces show dramatic differences. Callisto (with a diameter of 4817 kilometers) is "peppered" by impact craters, but is also covered by a dark material layer of so far unknown origin, as seen here in the region of the Asgard multi-ring basin. It appears that this layer erodes or covers small craters. Ganymede's landscape is also widely formed by impacts, but different from Callisto, much tectonic deformation can be observed in the Galileo images, such as these of Nicholson Regio. Ganymede, with a diameter of 5268 kilometers (one-and-a-half times larger than the Earth's moon), is the largest moon in the solar system. Contrary to Ganymede and Callisto, Europa (diameter 3121 kilometers) has a sparsely cratered surface, indicating that geologic activity took place more recently. Globally, ridged plains and the so-called "mottled terrain" are the main landforms. In the high-resolution image presented here showing the area around the Agave and Asterius dark lineaments, older ridges dominate the surface, while a small part of the younger mottled terrain is visible to the lower left of the image center. While all three moons are believed to be nearly as old as the solar system (4.5 billion years), the age of the surfaces, i.e. the time since the last major geologic activity took place, is still subject to debate. Without having surface samples in hand, the only method to roughly determine a planet's or satellite's geologic surface age is by crater counting. However, assumptions about the impactor fluxes must be made based on theoretical models and possible observations of candidate impactors such as asteroids and comets. Asteroids should have been very common in the early days of the solar system, but this source should have been largely exhausted by about 3.8 billion years before present. For comets, the impactor flux is believed to be rather constant throughout the whole lifetime of the solar system, meaning that the probability of an impact of a large comet is similar today as it was, say, four billion years ago. Assuming the asteroids have been the dominant bodies that impacted the Galilean satellites (which is believed to be the case on the Moon, the Earth, and other inner solar system bodies as well as within the asteroid belt itself), the surfaces of Ganymede and Callisto must be old, roughly four billion years. In this case, the Europan surface would by comparison have a mean age of one-hundred to several-hundred million years. Low-level geologic activity on Europa might be possible, but Ganymede and Callisto should be geologically dead. Assuming on the other hand that comets have been the main impactors in the Jovian system, Callisto's surface would still be determined to be old, but
Europa and Callisto under th …
PIA02861
Sol (our sun)
Imaging Science Subsystem
Title Europa and Callisto under the watchful gaze of Jupiter
Original Caption Released with Image One moment in an ancient, orbital dance is caught in this color picture taken by NASA's Cassini spacecraft on Dec. 7, 2000, just as two of Jupiter's four major moons, Europa and Callisto, were nearly perfectly aligned with each other and the center of the planet. The distances are deceiving. Europa, seen against Jupiter, is 600,000 kilometers (370,000 miles) above the planet's cloud tops. Callisto, at lower left, is nearly three times that distance from the cloud tops. Europa is a bit smaller than Earth's Moon and has one of the brightest surfaces in the solar system. Callisto is 50 percent bigger -- roughly the size of Saturn's largest satellite, Titan -- and three times darker than Europa. Its brightness had to be enhanced in this picture, relative Europa's and Jupiter's, in order for Callisto to be seen in this image. Europa and Callisto have had very different geologic histories but share some surprising similarities, such as surfaces rich in ice. Callisto has apparently not undergone major internal compositional stratification, but Europa's interior has differentiated into a rocky core and an outer layer of nearly pure ice. Callisto's ancient surface is completely covered by large impact craters: The brightest features seen on Callisto in this image were discovered by the Voyager spacecraft in 1979 to be bright craters, like those on our Moon. In contrast, Europa's young surface is covered by a wild tapestry of ridges, chaotic terrain and only a handful of large craters. Recent data from the magnetometer carried by the Galileo spacecraft, which has been in orbit around Jupiter since 1995, indicate the presence of conducting fluid, most likely salty water, inside both worlds. Scientists are eager to discover whether the surface of Saturn's Titan resembles that of Callisto or Europa, or whether it is entirely different when Cassini finally reaches its destination in 2004. Cassini is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini mission for NASA's Office of Space Science, Washington, D.C.
Capturing Callisto
PIA09258
Jupiter
LORRI
Title Capturing Callisto
Original Caption Released with Image The New Horizons Long Range Reconnaissance Imager (LORRI) captured these two images of Jupiter's outermost large moon, Callisto, as the spacecraft flew past Jupiter in late February. New Horizons' closest approach distance to Jupiter was 2.3 million kilometers (1.4 million miles), not far outside Callisto's orbit, which has a radius of 1.9 million kilometers (1.2 million miles). However, Callisto happened to be on the opposite side of Jupiter during the spacecraft's pass through the Jupiter system, so these images, taken from 4.7 million kilometers (3.0 million miles) and 4.2 million kilometers (2.6 million miles) away, are the closest of Callisto that New Horizons obtained. Callisto's ancient, crater-scarred surface makes it very different from its three more active sibling satellites, Io, Europa and Ganymede. Callisto, 4,800 kilometers (3000 miles) in diameter, displays no large-scale geological features other than impact craters, and every bright spot in these images is a crater. The largest impact feature on Callisto, the huge basin Valhalla, is visible as a bright patch at the 10 o'clock position. The craters are bright because they have excavated material relatively rich in water ice from beneath the dark, dusty material that coats most of the surface. The two images show essentially the same side of Callisto -- the side that faces Jupiter -- under different illumination conditions. The images accompanied scans of Callisto's infrared spectrum with New Horizons' Linear Etalon Imaging Spectral Array (LEISA). The New Horizons science team designed these scans to study how the infrared spectrum of Callisto's water ice changes as lighting and viewing conditions change, and as the ice cools through Callisto's late afternoon. The infrared spectrum of water ice depends slightly on its temperature, and a goal of New Horizons when it reaches the Pluto system (in 2015) is to use the water ice features in the spectrum of Pluto's moon Charon, and perhaps on Pluto itself, to measure surface temperature. Callisto provided an ideal opportunity to test this technique on a much better-known body. The left image, taken at 05:03 Universal Time on February 27, 2007, is centered at 5 degrees south, 5 degrees west, and has a solar phase angle of 46 degrees. The right image was taken at 03:25 Universal Time on February 28, 2007. It is centered at 4 degrees south, 356 degrees west, and has a solar phase angle of 76 degrees.
Callisto Scarp Mosaic
PIA00561
Jupiter
Solid-State Imaging
Title Callisto Scarp Mosaic
Original Caption Released with Image This mosaic of two images shows an area within the Valhalla region on Jupiter's moon, Callisto. North is to the top of the mosaic and the Sun illuminates the surface from the left. The smallest details that can be discerned in this picture are knobs and small impact craters about 155 meters (170 yards) across. The resolution is 46 meters (50 yards) per picture element, and the mosaic covers an area approximately 33 kilometers (20 miles) across. A prominent fault scarp crosses the mosaic. This scarp is one of many structural features that form the Valhalla multi-ring structure, which has a diameter of 4,000 kilometers (2,485 miles). Scientists believe Valhalla is the result of a large impact early in the history of Callisto. Several smaller ridges are found parallel to the prominent scarp. Numerous impact craters ranging in size from 155 meters (170 yards) to 2.5 kilometers (1.5 miles) are seen in the mosaic. The images which form this mosaic were obtained by the solid state imaging system aboard NASA's Galileo spacecraft on Nov. 4, 1996 (Universal Time). The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC. This image and other images and data received from Galileo are posted on the World Wide Web Galileo mission home page at http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo.
Callisto Crater Chain at Hig …
PIA00581
Jupiter
Solid-State Imaging
Title Callisto Crater Chain at High Resolution Shown in Context
Original Caption Released with Image A portion of a chain of impact craters on Jupiter's moon Callisto is seen in this image taken by the Galileo spacecraft on November 4, 1996. This crater chain on Callisto is believed to result from the impact of a split object, similar to the fragments of Comet Shoemaker-Levy 9 which smashed into Jupiter's atmosphere in July of 1994. This high-resolution view, taken by Galileo's solid state imaging television camera during its third orbit around Jupiter, is of Callisto's northern hemisphere at 35 degrees north, 46 degrees west, and covers an area of about eight miles (13 kilometers) across. The smallest visible crater is about 140 yards (130 meters) across. The image was taken at a range of 974 miles (1,567 kilometers). On a global scale, Callisto is heavily cratered, indicating the great age of its surface. At the scale of this image, it was anticipated that the surface would be heavily cratered as well, however, there is a surprising lack of small craters, suggesting that one or more processes have obliterated these and other small-scale features. For example, downslope movement of ice-rich debris could bury small craters. The bright slopes visible in this picture represent places where downslope movement has taken place, exposing fresh ice surfaces. The Jet Propulsion Laboratory manages the Galileo mission for NASA's Office of Space Science, Washington, DC. This image and other images and data received from Galileo are posted on the World Wide Web Galileo mission home page at http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http:// www.jpl.nasa.gov/galileo/sepo.
Callisto Crater Chain Mosaic
PIA00549
Jupiter
Solid-State Imaging
Title Callisto Crater Chain Mosaic
Original Caption Released with Image This mosaic of three images shows an area within the Valhalla region on Jupiter's moon, Callisto. North is to the top of the mosaic and the Sun illuminates the surface from the left. The smallest details that can be discerned in this picture are knobs and small impact craters about 160 meters (175 yards) across. The mosaic covers an area approximately 45 kilometers (28 miles) across. It shows part of a prominent crater chain located on the northern part of the Valhalla ring structure. Crater chains can form from the impact of material ejected from large impacts (forming secondary chains) or by the impact of a fragmented projectile, perhaps similar to the Shoemaker-Levy 9 cometary impacts into Jupiter in July 1994. It is believed this crater chain was formed by the impact of a fragmented projectile. The images which form this mosaic were obtained by the solid state imaging system aboard NASA's Galileo spacecraft on Nov. 4, 1996 (Universal Time). Launched in October 1989, Galileo entered orbit around Jupiter on December 7, 1995. The spacecraft's mission is to conduct detailed studies of the giant planet, its largest moons and the Jovian magnetic environment. The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC. This image and other images and data received from Galileo are posted on the World Wide Web Galileo mission home page at http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http:// www.jpl.nasa.gov/galileo/sepo.
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