|
|
Browse All
:
Earth and Moon and Galileo of Jet Propulsion Laboratory (JPL)
|
Printer Friendly |
Eruption on Io
This image, taken by NASA's
…
8/13/96
| Date |
8/13/96 |
| Description |
This image, taken by NASA's Galileo spacecraft, shows a new blue- colored volcanic plume extending about 100 kilometers (about 60 miles) into space from Jupiter's moon Io (see inset at lower left). The blue color of the plume is consistent with the presence of sulfur dioxide gas and "snow" condensing from the gas as the plume expands and cools. Galileo images have also shown that the Ra Patera plume glows in the dark, perhaps due to the fluorescence of sulfur and oxygen ions created by the breaking apart of sulfur dioxide molecules by energetic particles in the Jovian magnetosphere. The images at right show a comparison of changes seen near the volcano Ra Patera since the Voyager spacecraft flybys of 1979 (windows at right show Voyager image at top and Galileo image at bottom). This eruptive plume is an example of a new type of volcanic activity discovered during Voyager's flyby in 1979, believed to be geyser- like eruptions driven by sulfur dioxide or sulfur gas erupting and freezing in Io's extremely tenuous atmosphere. Volcanic eruptions on Earth cannot throw materials to such high altitudes. Ra Patera is the site of dramatic surface changes. An area around the volcano of about 40,000 square kilometers, area about the size of New Jersey, has been covered by new volcanic deposits. The image was taken in late June 28, 1996 from a distance of 972,000 kilometers (604,000 miles). The Galileo mission is managed by NASA's Jet Propulsion Laboratory. |
|
GLL/EM15
This mosaic picture of the M
…
12/22/92
| Date |
12/22/92 |
| Description |
This mosaic picture of the Moon was compiled from 18 images taken with a green filter by Galileo's imaging system during the spacecraft's flyby on December 7, 1992, some 11 hours before its Earth flyby at 1509 UTC (7:09 a.m. Pacific Standard Time) December 8. The north polar region is near the top part of the mosaic, which also shows Mare Imbrium, the dark area on the left, Mare Serenitatis at center, and Mare Crisium, the circular dark area to the right. Bright crater rim and ray deposits are from Copernicus, an impact crater 96 kilometers (60 miles) in diameter. Computer processing has exaggerated the brightness of poorly illuminated features near the day/night terminator in the polar regions, giving a false impression of high reflectivity there. The digital image processing was done by DLR the German aerospace research establishment near Munich, an international collaborator in the Galileo mission. The Galileo project, whose primary mission is the exploration of the Jupiter system in 1995-97, is managed for NASA's Office of Space Science and Applications by the Jet Propulsion Laboratory. ##### |
|
GLL/EM16
This view looking down on th
…
| Description |
This view looking down on the north pole of the Moon was assembled from 18 images taken with a green filter by Galileo's imaging system as the spacecraft flew by the Moon on December 7, 1992. The part of the moon visible from Earth is toward the left and includes the dark, lava-filled Imbrium basin, upper left, Mare Serenitatis, middle left, Mare Tranquillitatis, lower left, and Crisium, the dark circular feature toward the bottom of the mosaic. Also visible in this view are the dark lava plains of the Marginis and Smythii basins, lower right. The Humboldtianum Basin, a 650-kilometer (400-mile) impact structure partly filled with dark volcanic deposits, is visible in the middle of the image. The Moon's north pole is located just inside the shadow zone about a third of the way from the top left of the lighted region. The Galileo project, whose primary mission is the exploration of the Jupiter system in 1995-97, is managed for NASA's Office of Space Science and Applications by the Jet Propulsion Laboratory. ##### |
|
GLL/EM17
This false-color mosaic was
…
12/22/92
| Date |
12/22/92 |
| Description |
This false-color mosaic was constructed from a series of 53 images taken through three spectral filters by Galileo's imaging system as the spacecraft flew over the northern regions of the Moon on December 7, 1992. The part of the Moon vlsible from Earth is on the left side in this view. The color mosaic shows compositional variations in parts of the Moon's northern hemisphere. Bright pinkish areas are highlands materials, such as those surrounding the oval lava-filled Crisium impact basin toward the bottom of the picture. B1ue to orange shades indicate volcanic lava flows. To the left of Crisium, the dark blue Mare Tranquillitatis is richer in titanium than the green and orange maria above it. Thin mineral-rich soils associated with relatively recent impacts are represented by light blue colors, the youngest craters have prominent blue rays extending from them. The Galileo project, whose primary mission is the exploration of the Jupiter system in 1995-97, is managed for NASA's Office of Space Science and Applications by the Jet Propulsion Laboratory. ##### |
|
GALILEO
This image is the most detai
…
6/22/94
| Date |
6/22/94 |
| Description |
This image is the most detailed picture of the recently discovered natural satellite of asteroid 243 Ida taken by the Galileo Solid-State Imaging camera during its encounter with the asteroid on August 28, 1993. Shuttered through the camera's broadband clear filter as part of a 30-frame mosaic designed to image the asteroid itself, this frame fortuitously captured the previously unknown moon at a range of about 3,900 kilometers (2,400 miles), just over 4 minutes before the spacecraft's closest approach to Ida. Each picture element spans about 39 meters (125 feet) on the surface of the moon. More than a dozen craters larger than 80 meters (250 feet) in diameter are clearly evident, indicating that the moon has suffered numerous collisions from smaller Solar System debris during its history. The larger crater on the terminator is about 300 meters (1,000 feet) across. The satellite is approximately egg-shaped, measuring about 1.2 x 1.4 x 1.6 kilometers (0.75 x 0.87 x 1 mile). At the time this image was shuttered, Ida was about 90 kilometers (56 miles) away from the moon, outside this frame to the left and slightly below center. This image was relayed to Earth from Galileo on June 8, 1994. The Galileo project, whose primary mission is the exploration of the Jupiter system in 1995-97, is managed for NASA's Office of Space Science by the Jet Propulsion Laboratory. ##### |
|
Terrain near Io's south pole
Volcanic calderas, lava flow
…
4/19/00
| Date |
4/19/00 |
| Description |
Volcanic calderas, lava flows and cliffs are seen in this false color image of a region near the south pole of Jupiter's volcanic moon Io. It was created by combining a black and white image taken by NASA's Galileo spacecraft on February 22, 2000 with lower resolution color images taken by Galileo on July 3, 1999. The three black spots (top center and middle left) are small volcanic calderas about 10-20 kilometers (6-12 miles) in size, which are dark because their floors are covered by recent lava flows. Two of these three calderas are surrounded by diffuse dark material, which may have been thrown out of the calderas by explosive eruptions. The bright, white material is thought to be sulfur-dioxide frost and is concentrated near the cliffs in this image. It may be formed when liquid sulfur dioxide seeps out at the base of mountain scarps, vaporizes into a plume of gas, liquid and solid, and then condenses again on the surface. Part of this process, called sapping, occurs in arid environments on Earth when ground water seeps out at the bases of cliffs. The vaporization and production of plumes is much more dramatic on Io due to the lower gravitational acceleration and especially the very low atmospheric pressure. It may be one of the dominant erosion processes on Io. The mountain at the center left, named Telegonus Mensae, exhibits a number of ridges parallel to its margins. These ridges have been observed on a number of other Ionian mountains and they suggest that as the mountain ages, it is collapsing outward under the influence of gravity. The yellow lava flow at the southern end of the image appears to be fed by a dark channel that connects to a dark caldera. This is a likely candidate for a lava flow composed of sulfur (rather than silicate material). The image is centered at 53.8 degrees south latitude and 117.1 degrees west longitude and north is to the top. The higher resolution image has a resolution of 350 meters (or yards) per picture element and is illuminated from the upper left. It was taken at a range of 34,000 kilometers (21,000 miles). The color images have resolutions of 1.3 kilometers (0.81 miles) per picture element and are illuminated from almost directly behind the spacecraft. They were taken at a distance of about 130,000 kilometers (81,000 miles) by Galileo's onboard camera. The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is a division of the California Institute of Technology, Pasadena, CA. This image and other images and data received from Galileo are posted 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://galileo.jpl.nasa.gov/images/io/ioimages.html . ##### |
|
Caldera-like depression on G
…
The shallow, scalloped depre
…
12/16/00
| Date |
12/16/00 |
| Description |
The shallow, scalloped depression in the center of this picture from NASA's Galileo spacecraft is a caldera-like feature 5 to 20 kilometers (3 to 12 miles) wide on Jupiter's largest moon, Ganymede. Calderas are surface depressions formed by collapse above a subsurface concentration of molten material. Some shallow depressions in bright, smooth areas of Ganymede have some overall similarities to calderas on Earth and on Jupiter's moon Io. On Ganymede, caldera-like depressions may serve as sources of bright, volcanic flows of liquid water and slush, an idea supported by a Ganymede photo obtained by Galileo during its seventh orbit and available at http://photojournal.jpl.nasa.gov/cgi- bin/PIAGenCatalogPage.pl?PIA01614 . In the more recent image here, from Galileo's 28th orbit, a tall scarp marks the western boundary of a caldera-like feature. The western scarp is aligned similarly to older tectonic grooves visible in the image, suggesting the feature has collapsed along older lines of weakness. The interior is mottled in appearance, yet smooth compared to most of Ganymede's bright terrain seen at high resolution. The eastern boundary of the caldera-like feature is cut by younger, grooved terrain. Small impact craters pepper the scene, but the lack of a raised rim argues against an impact origin for the caldera-like feature itself. Instead, water-rich icy lava may have once flowed out of it toward the east. If so, later tectonism could have erased any telltale evidence of volcanic flow fronts. Direct evidence for icy volcanism on Ganymede continues to be elusive. North is to the top of the picture and the Sun illuminates the surface from the left. The image, centered at -24 degrees latitude and 318 degrees longitude, covers an area approximately 162 by 119 kilometers (101 by 74 miles). The resolution is 43 meters (141 feet) per picture element. This image and other images and data received from Galileo are posted 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 . 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. This image was produced by Brown University, Providence, R.I., http://www.planetary.brown.edu/ . # # # # # |
|
Eruption at Tvashtar Catena
…
This pair of images taken by
…
2/26/01
| Date |
2/26/01 |
| Description |
This pair of images taken by NASA's Galileo spacecraft captures a dynamic eruption at Tvashtar Catena, a chain of volcanic bowls on Jupiter's moon Io. They show a change in the location of hot lava over a period of a few months in 1999 and early 2000. The image on the left uses data obtained on Nov. 26 and July 3, 1999, at resolutions of 183 meters (600 feet) and 1.3 kilometers (0.8 miles) per pixel, respectively. The red and yellow lava flow itself is an illustration based upon imaging data. The image on the right is a composite using a five-color observation made on Feb. 22, 2000, at 315 meters (1030 feet) per pixel. These are among the most fortuitous observations made by Galileo because this style of volcanism is too unpredictable and short-lived to plan to photograph. Short-lived bursts of volcanic activity on Io had been previously detected from Earth-based observations, but interpreting the style of volcanic activity from those lower- resolution views was highly speculative. These Galileo observations confirm hypotheses that the initial, intense thermal output comes from active lava fountains. Galileo's high-resolution observations of volcanic activity on Io have also confirmed other hypotheses based on earlier, low- resolution data. These include interpretations of slowly spreading lava flows at Prometheus and Amirani and an active lava lake at Pele. These tests of earlier hypotheses increase scientists' confidence in interpreting volcanic activity seen in low-resolution remote sensing data of Earth as well as Io. However, these data are still of insufficient resolution to adequately test the more quantitative models that have been applied to volcanic eruptions on Earth and Io. These images also show other geologic features on Io, such as the scalloped margins of the plateau to the northeast of the active lavas. These margins appear to have formed by sapping, a process usually associated with springs of water. Liquid sulfur dioxide might be the fluid responsible for sapping on Io. A better understanding of sapping on Io will influence how scientists interpret similar features on Mars (where the viability of carbon dioxide or water as the sapping fluid remains controversial). Images and data received from Galileo are posted 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 . 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. # # # # # |
|
Amirani's Big Lava Flow on I
…
These images from NASA's Gal
…
2/26/01
| Date |
2/26/01 |
| Description |
These images from NASA's Galileo spacecraft show changes in the largest active field lava flows in the solar system, the Amirani lava flow on Jupiter's moon Io. Scientists have identified 23 distinct new flows by comparing the two images taken 134 days apart, on Oct. 11, 1999, and Feb. 22, 2000. The Amirani lava-flow field spans more than 300 kilometers (190 miles). Individual flows within it are each several kilometers or miles long, which is about the size of the entire active eruption on Kilauea, Hawaii. In total, the new lava flows at Amirani covered about 620 square kilometers (240 square miles) of Io in less than five months. By comparison, Kilauea covered only about 10 square kilometers (4 square miles) in the same time. Amirani is huge even when compared to other Ionian lava flows: The Prometheus lava flow field covered only about 60 square kilometers (24 square miles) during this time. Galileo scientists are studying Amirani to understand how such large lava flows are created. The last eruption this size on Earth happened about 15 million years ago along the Columbia River in what is now the state of Washington. Many scientists thought that such long lava flows were formed in violent volcanic outbursts. However, the eruption observed at Amirani is relatively calm, despite the fact that over 100 tons of lava are disgorged every second. Galileo's observations of Io indicate that huge, ancient lava flows on the Earth, such as the Columbia River flood basalts, could also have formed in relatively tranquil eruptions. The color image on the left is a composite of black-and- white images collected on Feb. 22, 2000, at a resolution of 210 meters (690 feet) per picture element, and color images collected on June 30, 1999, at 1.3 kilometers (0.8 mile) per picture element. The white boxes and arrows show the locations of the areas analyzed in detail on the right. The left-hand pair of black-and-white images, labeled I24, are parts of a mosaic collected on Oct. 11, 1999, at 500 meters (550 yards) per picture element. The center pair of images, labeled I27, shows what the same areas looked like on Feb. 22, 2000. These later images are about twice as sharp as the earlier images, making some features that did not change appear crisper. In order to demonstrate the real changes, the I27 images were divided by the I24 images, producing the pair of ratio images on the right. The new dark lava that erupted between October 1999 and February 2000 has been highlighted in red. Images and data received from Galileo are posted 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 . 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. # # # # # |
|
| 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 |
Jupiter's four largest satellites, including Io, the golden ornament in front of Jupiter in this image from NASA's Cassini spacecraft, have fascinated Earthlings ever since Galileo Galilei discovered them in 1610 in one of his first astronomical uses of the telescope. Images from Cassini that will be released over the next several days capture each of the four Galilean satellites in their orbits around the giant planet. This true-color composite frame, made from narrow angle images taken on Dec. 12, 2000, captures Io and its shadow in transit against the disk of Jupiter. The distance of the spacecraft from Jupiter was 19.5 million kilometers (12.1 million miles). The image scale is 117 kilometers (73 miles) per pixel. The entire body of Io, about the size of Earth's Moon, is periodically flexed as it speeds around Jupiter and feels, as a result of its non-circular orbit, the periodically changing gravitational pull of the planet. The heat arising in Io's interior from this continual flexure makes it the most volcanically active body in the solar system, with more than 100 active volcanoes. The white and reddish colors on its surface are due to the presence of different sulfurous materials. The black areas are silicate rocks. 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. |
|
| 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 |
This color image of Jupiter was taken by the camera onboard NASA's Cassini spacecraft when it was 81.3 million kilometers (50.5 million miles) from the planet. It is composed of images taken in the blue, green, and red regions of the spectrum and is therefore close to the true color of Jupiter that one would see through an Earth-based telescope. The image is remarkably similar to images taken by NASA's Voyager 1 and 2 spacecraft more than 21 years ago, illustrating the stability of Jupiter's weather patterns. The parallel dark and bright bands and many other large-scale features are quasi-permanent structures that survive despite the intense small-scale activity ongoing in the atmosphere. The longevity of the large-scale features is an intrinsic property of the atmospheric flows on a gaseous planet such as Jupiter, with no solid surface. Smaller features, such as those in the dark bands north and south of the equator, are observed to form and disappear in a few days. Everything visible on the planet is a cloud. Unlike Earth, where only water condenses to form clouds, Jupiter has several cloud-forming substances in its atmosphere. The updrafts and downdrafts bring different mixtures of these substances up from below, leading to clouds of different colors. The bluish features just north of the equator are regions of reduced cloud cover, similar to the place where the Galileo atmospheric probe entered in 1995. They are called "hot spots" because the reduced cloud cover allows heat to escape from warmer, deeper levels in the atmosphere. Jupiter's moon Europa is seen at the right, casting a shadow on the planet. Scientists believe Europa holds promise of a liquid ocean beneath its surface. 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, Calif., manages the Cassini mission for NASA's Office of Space Science, Washington, D.C. Credit: NASA/JPL/University of Arizona, (PIA02972) For higher resolution, click here. |
|
| 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. |
|
| 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 |
Jupiter's Magnetosphere Made Visible February 27, 2002 The vast magnetosphere of charged particles whirling around Jupiter, normally invisible, can be imaged by a new type of instrument aboard NASA's Cassini spacecraft and is seen here. Three features are sketched in for context: a black circle showing the size of Jupiter, lines of Jupiter's magnetic field, and a cross-section of the Io torus, a doughnut-shaped ring of charged particles that originate from volcanic eruptions on Jupiter's moon Io and circle Jupiter at about the orbit of Io. Jupiter's magnetosphere is the largest object in the solar system. If it glowed in wavelengths visible to the eye, it would appear two to three times the size of the Sun or Moon to viewers on Earth. Cassini's ion and neutral camera detects neutral atoms expelled from the magnetosphere, deriving information about their source. This image was taken shortly after Cassini's closest approach to Jupiter, about 10 million kilometers (6 million miles) from the planet on Dec. 30, 2000. For more information about the Saturn-bound spacecraft and its observations of Jupiter, see the Cassini home page, http://saturn.jpl.nasa.gov. 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/Johns Hopkins University Applied Physics Laboratory More information about the Cassini and Galileo joint observations of the Jupiter system is available online at: http://www.jpl.nasa.gov/jupiterflyby. 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 Galileo and Cassini missions for NASA's Office of Space Science, Washington, D.C. For higher resolution, click here. |
|
Europa Exploration Concept
| title |
Europa Exploration Concept |
| description |
Almost 30 years ago, NASA's Voyagers 1 and 2 (lower left) made their historic rendezvous with the Jupiter system and first revealed Europa's icy-covered surface. In 1995, the Galileo spacecraft entered orbit about Jupiter, and for years studied the giant planet and its major moons. From this mission we learned that Europa is a world covered with a global ocean about 100 kilometers (60 miles) deep, and that this ocean was capped, liked Earth's Arctic Ocean, with a shell of solid ice. To learn more about the ocean and the ice shell above, and especially to investigate the ocean's suitability to sustain life, will require the next step, a future mission dedicated to exploring Europa from orbit about the moon itself (center). Both NASA and the European Space Agency are actively studying the possibility of launching such a mission in the next 10 years. If a mission is launched, depending on what is found, future missions to Europa might involve landers or even autonomous vehicles, called cryobots (upper right), that melt through the ice to explore the ocean below, perhaps sometime later in this century. Credit: NASA/JPL |
|
The Earth-Moon System
| title |
The Earth-Moon System |
| date |
12.16.1992 |
| description |
Eight days after its final encounter with the Earth, the Galileo spacecraft looked back and captured this remarkable view of the Earth and Moon. The image was taken from a distance of about 6.2 million kilometers (3.9 million miles). The picture was constructed from images taken through the violet, red, and 1.0-micron infrared filters. The Moon is in the foreground, moving from left to right. The brightly-colored Earth contrasts strongly with the Moon, which reflects only about one-third as much sunlight as the Earth. Contrast and color have been computer-enhanced for both objects to improve visibility. Antarctica is visible through clouds (bottom). The Moon's far side is seen, the shadowy indentation in the dawn terminator is the south pole Aitken Basin, one of the largest and oldest lunar impact features. *Image Credit*: NASA |
|
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 |
|
High Resolution View of Dact
…
| title |
High Resolution View of Dactyl |
| date |
08.28.1993 |
| description |
This image is the most detailed picture of the recently discovered natural satellite of asteroid 243 Ida taken by the Galileo Solid-State Imaging camera during its encounter with the asteroid on August 28, 1993. Shuttered through the camera's broadband clear filter as part of a 30-frame mosaic designed to image the asteroid itself, this frame fortuitously captured the previously unknown moon at a range of about 3,900 kilometers (2,400 miles), just over 4 minutes before the spacecraft's closest approach to Ida. Each picture element spans about 39 meters (125 feet) on the surface of the moon. More than a dozen craters larger than 80 meters (250 feet) in diameter are clearly evident, indicating that the moon has suffered numerous collisions from smaller Solar System debris during its history. The larger crater on the terminator is about 300 meters (1,000 feet) across. The satellite is approximately egg-shaped, measuring about 1.2 x 1.4 x 1.6 kilometers (0.75 x 0.87 x 1 mile). At the time this image was shuttered, Ida was about 90 kilometers (56 miles) away from the moon, outside this frame to the left and slightly below center. This image was relayed to Earth from Galileo on June 8, 1994. The Galileo project, whose primary mission is the exploration of the Jupiter system in 1995-97, is managed for NASA's Office of Space Science by the Jet Propulsion Laboratory. *Image Credit*: JPL |
|
Moon - False Color Mosaic
| title |
Moon - False Color Mosaic |
| date |
12.08.1992 |
| description |
This false-color photograph is a composite of 15 images of the Moon taken through three color filters by Galileo's solid-state imaging system during the spacecraft's passage through the Earth-Moon system on December 8, 1992. When this view was obtained, the spacecraft was 425,000 kilometers (262,000 miles) from the Moon and 69,000 kilometers (43,000 miles) from Earth. The false-color processing used to create this lunar image is helpful for interpreting the surface soil composition. Areas appearing red generally correspond to the lunar highlands, while blue to orange shades indicate the ancient volcanic lava flow of a mare, or lunar sea. Bluer mare areas contain more titanium than do the orange regions. Mare Tranquillitatis, seen as a deep blue patch on the right, is richer in titanium than Mare Serenitatis, a slightly smaller circular area immediately adjacent to the upper left of Mare Tranquillitatis. Blue and orange areas covering much of the left side of the Moon in this view represent many separate lava flows in Oceanus Procellarum. The small purple areas found near the center are pyroclastic deposits formed by explosive volcanic eruptions. The fresh crater Tycho, with a diameter of 85 kilometers (53 miles), is prominent at the bottom of the photograph, where part of the Moon's disk is missing. *Image Credit*: JPL |
|
Far Side of the Moon
| title |
Far Side of the Moon |
| description |
This image of the moon was obtained by the Galileo Solid State imaging system on Dec. 8 at 7 p.m. PST as the Galileo spacecraft passed the Earth and was able to view the lunar surface from a vantage point not possible from the Earth. On the right-hand side of the image is seen the dark maria of Oceanus Procellarum, also visible from the Earth. The dark spots in the center are Mare Orientale, on the western limb of the nearside of the moon, a region barely visible from the Earth. This region and the bright far side highlands on the left have not been seen previously by a camera system such as the one on the Galileo spacecraft, which provides multispectral images of the lunar limb and far side which have not previously been obtained. Comparison of such images to those of the near-side areas from which Apollo astronauts have returned samples will help us understand the spectral properties and composition of the lunar far side. *Image Credit*: JPL |
|
Asteroid Gaspra's True Color
…
| title |
Asteroid Gaspra's True Colors |
| date |
10.29.1991 |
| description |
These two color views of the asteroid Gaspra were produced by combining three images taken through violet, green, and infrared filters by the Galileo spacecraft on October 29, 1991, from a distance of about 16,000 kilometers. The view on the left shows Gaspra in approximately true color, the surface is covered with rocks that are somewhat less gray than those on Earth's Moon. In the version on the right, the colors were enhanced to bring out the muted color variations on the asteroid and to increase the ability to discriminate between surface features. The subtle variations in color may be due to slight differences in rock composition or to differences in the texture of the surface layer. Gaspra is about 19 x 12 x 11 kilometers and irregular in shape. The illuminated portion seen in these views is about 16 x 12 kilometers. These color images were produced for the Galileo project by the U.S. Geological survey, Flagstaff, Arizona. The Galileo project, whose primary mission was the exploration of the Jupiter system, was managed for NASA's Office of Space Science and Applications by the Jet Propulsion Laboratory. *Image Credit*: U.S. Geological Survey |
|
An Eruption on Io
| title |
An Eruption on Io |
| date |
02.26.2007 |
| description |
The first images returned to Earth by New Horizons during its close encounter with Jupiter feature the Galilean moon Io, snapped with the Long Range Reconnaissance Imager (LORRI) at 0840 UTC on February 26, while the moon was 2.5 million miles (4 million kilometers) from the spacecraft. Io is intensely heated by its tidal interaction with Jupiter and is thus extremely volcanically active. That activity is evident in these images, which reveal an enormous dust plume, more than 150 miles high, erupting from the volcano Tvashtar. The plume appears as an umbrella-shaped feature of the edge of Io's disk in the 11 o'clock position in the right image, which is a long-exposure (20-millisecond) frame designed specifically to look for plumes like this. The bright spots at 2 o'clock are high mountains catching the setting sun, beyond them the night side of Io can be seen, faintly illuminated by light reflected from Jupiter itself. The left image is a shorter exposure -- 3 milliseconds -- designed to look at surface features. In this frame, the Tvashtar volcano shows as a dark spot, also at 11 o'clock, surrounded by a large dark ring, where an area larger than Texas has been covered by fallout from the giant eruption. This is the clearest view yet of a plume from Tvashtar, one of Io's most active volcanoes. Ground-based telescopes and the Galileo Jupiter orbiter first spotted volcanic heat radiation from Tvashtar in November 1999, and the Cassini spacecraft saw a large plume when it flew past Jupiter in December 2000. The Keck telescope in Hawaii picked up renewed heat radiation from Tvashtar in spring 2006, and just two weeks ago the Hubble Space Telescope saw the Tvashtar plume in ultraviolet images designed to support the New Horizons flyby. Most of those images will be stored onboard the spacecraft for downlink to Earth in March and April. Image Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute |
|
Montage of Neptune and Trito
…
| Title |
Montage of Neptune and Triton |
| Full Description |
This computer generated montage shows Neptune as it would appear from a spacecraft approaching Triton, Neptune's largest moon at 2706 km (1683 mi) in diameter. The wind and sublimation eroded south polar cap of Triton is shown at the bottom of the Triton image, a cryovolcanic terrain at the upper right, and the enigmatic "cantaloupe terrain" at the upper left. Triton's surface is mostly covered by nitrogen frost mixed with traces of condensed methane, carbon dioxide, and carbon monoxide. The tenuous atmosphere of Triton, though only about one hundredth of one percent of Earth's atmospheric density at the surface, is thick enough to produce wind-deposited streaks of dark and bright materials of unknown composition in the south polar cap region. The southern polar cap was sublimating at the time of the Voyager 2 flyby, as indicated by the irregular and eroded appearance of the edge of the cap. |
| Date |
01/06/1990 |
| NASA Center |
Jet Propulsion Laboratory |
|
Solar System Montage
| Title |
Solar System Montage |
| Full Description |
This is a montage of planetary images taken by spacecraft managed by the Jet Propulsion Laboratory in Pasadena, CA. Included are (from top to bottom) images of Mercury, Venus, Earth (and Moon), Mars, Jupiter, Saturn, Uranus and Neptune. The spacecraft responsible for these images are as follows: the Mercury image was taken by Mariner 10, the Venus image by Magellan, the Earth image by Galileo, the Mars image by Viking, and the Jupiter, Saturn, Uranus and Neptune images by Voyager. Pluto is not shown as no spacecraft has yet visited it. The inner planets (Mercury, Venus, Earth, Moon, and Mars) are roughly to scale to each other, the outer planets (Jupiter, Saturn, Uranus, and Neptune) are roughly to scale to each other. Actual diameters are given below: Sun 1,390,000 km Mercury 4,879 km Venus 12,104 km Earth 12,756 km Moon 3,475 km Mars 6,794 km Jupiter 142.984 km Saturn 120,536 km Uranus 51,118 km Neptune 49,528 km Pluto 2,390 km |
| Date |
04/09/1999 |
| NASA Center |
Jet Propulsion Laboratory |
|
Solar System Montage of Voya
…
| Title |
Solar System Montage of Voyager Images |
| Full Description |
This montage of images taken by the Voyager spacecraft of the planets and four of Jupiter's moons is set against a false-color Rosette Nebula with Earth's moon in the foreground. Studying and mapping Jupiter, Saturn, Uranus, Neptune, and many of their moons, Voyager provided scientists with better images and data than they had ever had before or expected from the program. Although launched sixteen days after Voyager 2, Voyager 1's trajectory was a faster path, arriving at Jupiter in March 1979. Voyager 2 arrived about four months later in July 1979. Both spacecraft were then directed to Saturn with Voyager 1 arriving in November 1980 and Voyager 2 in August 1981. Voyager 2 was then diverted to the remaining gas giants, Uranus in January 1986 and Neptune in August 1989. Data collection continues by both Voyager 1 and 2 as the renamed Voyager Interstellar Mission searches for the edge of the solar wind influence (the heliopause) and exits the Solar System. A shortened list of the discoveries of Voyager 1 and 2 include:the discovery of the Uranian and Neptunian magnetospheres (magnetic environments caused by various types of planet cores), the discovery of twenty-two new satellites including three at Jupiter, three at Saturn, ten at Uranus, and six at Neptune, Io was found to have active volcanism (the only other Solar System body than Earth to be confirmed), Triton was found to have active geyser-like structures and an atmosphere, Auroral Zones (where gases become excited after being hit by solar particles) were discovered at Jupiter, Saturn, and Neptune, Jupiter was found to have rings, Neptune, originally thought to be too cold to support such atmospheric disturbances, had large-scale storms. |
| Date |
UNKNOWN |
| NASA Center |
Jet Propulsion Laboratory |
|
False-Color Lunar Image
| Title |
False-Color Lunar Image |
| Full Description |
This false-color photograph is a composite of 15 images of the Moon taken through three color filters by the Galileo spacecraft?s solid-state imaging system during the spacecraft?s passage through the Earth-Moon system on December 8, 1992. When this view was obtained, the spacecraft was 425,000 kilometers (262,000 miles) from the Moon and 69,000 kilometers (43,000 miles) from Earth. The false-color processing used to create this lunar image is helpful for interpreting the surface soil composition. Areas appearing red generally correspond to the lunar highlands, while blue to orange shades indicate the ancient volcanic lava flow of a mare, or lunar sea. Bluer mare areas contain more titanium than do the orange regions. Mare Tranquillitatis, seen as a deep blue patch on the right, is richer in titanium than mare Serenitatis, a slightly smaller circular area immediately adjacent to the upper left o Mare Tranquillitatis. Blue and orange areas covering much of the left side of the Moon in this view represent many separate lava flows in Oceanus Procellarum. The small purple areas found near the center are pyroclastic deposits formed by explosive volcanic eruptions. The fresh crater Tycho, with a diameter of 85 kilometers (53 miles), is prominent at the bottom of the photograph, where part of the moon disk is missing. |
| Date |
04/1993 |
| NASA Center |
Jet Propulsion Laboratory |
|
First Picture of the Earth a
…
| Title |
First Picture of the Earth and Moon in a Single Frame |
| Full Description |
This picture of the Earth and Moon in a single frame, the first of its kind ever taken by a spacecraft, was recorded September 18, 1977, but NASAs Voyager 1 when it was 7.25 million miles (11.66 million kilometers) from Earth. The moon is at the top of the picture and beyond the Earth as viewed by Voyager. In the picture are eastern Asia, the western Pacific Ocean and part of the Arctic. Voyager 1 was directly above Mt. Everest (on the night side of the planet at 25 degrees north latitude) when the picture was taken. The photo was made from three images taken through color filters, then processed by the Image Processing Lab at Jet Propulsion Laboratory (JPL). Because the Earth is many times brighter than the Moon, the Moon was artificially brightened by a factor of three relative to the Earth by computer enhancement so that both bodies would show clearly in the prints. Voyager 1 was launched September 5, 1977 and Voyager 2 on August 20, 1977. JPL is responsible for the Voyager mission. |
| Date |
09/18/1977 |
| NASA Center |
Jet Propulsion Laboratory |
|
Galileo Images the Moon
| Title |
Galileo Images the Moon |
| Full Description |
This view of the Moon's north pole is a mosaic assembled from 18 images taken by Galileo's imaging system through a green filter as the spacecraft flew by on December 7, 1992. The left part of the Moon is visible from Earth, this region includes the dark, lava-filled Mare Imbrium (upper left), Mare Serenitatis (middle left), Mare Tranquillitatis (lower left), and Mare Crisium, the dark circular feature toward the bottom of the mosaic. Also visible in this view are the dark lava plains of the Marginis and Smythii Basins at the lower right. The Humboldtianum Basin, a 650-kilometer (400-mile) impact structure partly filled with dark volcanic deposits, is seen at the center of the image. The Moon's north pole is located just inside the shadow zone, about a third of the way from the top left of the illuminated region. |
| Date |
12/14/1992 |
| NASA Center |
Jet Propulsion Laboratory |
|
Global Color Mosaic of Trito
…
| Title |
Global Color Mosaic of Triton |
| Full Description |
Global color mosaic of Triton, taken in 1989 by Voyager 2 during its flyby of the Neptune system. Color was synthesized by combining high- resolution images taken through orange, violet, and ultraviolet filters, these images were displayed as red, green, and blue images and combined to create this color version. With a radius of 1,350 (839 mi), about 22% smaller than Earth's moon, Triton is by far the largest satellite of Neptune. It is one of only three objects in the Solar System known to have a nitrogen-dominated atmosphere (the others are Earth and Saturn's giant moon, Titan). Triton has the coldest surface known anywhere in the Solar System (38 K, about -391 degrees Farenheit), it is so cold that most of Triton's nitrogen is condensed as frost, making it the only satellite in the Solar System known to have a surface made mainly of nitrogen ice. The pinkish deposits constitute a vast south polar cap believed to contain methane ice, which would have reacted under sunlight to form pink or red compounds. The dark streaks overlying these pink ices are believed to be an icy and perhaps carbonaceous dust deposited from huge geyser-like plumes, some of which were found to be active during the Voyager 2 flyby. The bluish-green band visible in this image extends all the way around Triton near the equator, it may consist of relatively fresh nitrogen frost deposits. The greenish areas include what is called the cataloupe terrain, whose origin is unknown, and a set of "cryovolcanic" landscapes apparently produced by icy-cold liquids (now frozen) erupted from Triton's interior. |
| Date |
05/01/1980 |
| NASA Center |
Jet Propulsion Laboratory |
|
The Earth and Moon
| Title |
The Earth and Moon |
| Full Description |
During its flight, the Galileo spacecraft returned images of the Earth and Moon. Separate images of the Earth and Moon were combined to generate this view. The Galileo spacecraft took the images in 1992 on its way to explore the Jupiter system in 1995-97. The image shows a partial view of the Earth centered on the Pacific Ocean about latitude 20 degrees south. The west coast of South America can be observed as well as the Caribbean, swirling white cloud patterns indicate storms in the southeast Pacific. The distinct bright ray crater at the bottom of the Moon is the Tycho impact basin. The lunar dark areas are lava rock filled impact basins. This picture contains same scale and relative color/albedo images of the Earth and Moon. False colors via use of the 1-micron filter as red, 727-nm filter as green, and violet filter as blue. The Galileo project is managed for NASA's Office of Space Science by the Jet Propulsion Laboratory. |
| Date |
01/02/1990 |
| NASA Center |
Jet Propulsion Laboratory |
|
Voyager 1 Image of Ganymede
| Title |
Voyager 1 Image of Ganymede |
| Full Description |
Voyager 1 took this picture of Ganymede from a distance of 1.6 million miles. Ganymede is Jupiter's largest satellite with a radius of approximately 2600 kilometers, about 1.5 times that of Earth's Moon. Ganymede is the seventh and largest of Jupiter's known satellites and is the third of the Galilean moons. Discovered in 1610 by Galileo and Marius, Ganymede is the largest satellite in the Solar System. It was named after the Greek mythical character, Ganymede, a handsome Trojan boy that Zeus took to Olympus to be a cupbearer for the gods (one of the only humans in Greek mythology who became immortal). Ganymede is larger than Mercury but has only half Mercury's mass. It has a bulk density of only two grams per cubic centimeter, almost half that of Earth's Moon. Ganymede is most likely composed of a mixture of rock and ice. The long white filaments resemble rays associated with impacts on the lunar surface. The various colors of different regions probably represent differing surface materials. Several dots of a single color (blue, green, and orange) on the picture are the result of markings on the camera used for pointing determinations and are not physical markings. Voyager scientists discovered that Ganymede has its own magnetosphere embedded inside Jupiter's large one. JPL manages and controls the Voyager Project for NASA's Office of Space Science. |
| Date |
03/04/1979 |
| NASA Center |
Jet Propulsion Laboratory |
|
Hubble Follows Rapid Changes
…
| Title |
Hubble Follows Rapid Changes in Jupiter's Aurora |
|
A91-2015
Photographer : JPL This imag
…
12/8/90
| Description |
Photographer : JPL This image of the crescent moon was obtained by the Galileo Solid-State Imaging System, taken at 5 am PST as the spacecraft neared Earth. The image was taken through a green filter and shows the western part of the lunar near side. The smallest features visible are 8 km (5 mi) in size. Major features visible include the dark plains of Mare Imbrium in the upper part of the image, the bright crater Copernicus (100 km, 60 miles in diameter) in the centeral part, and the heavily cratered lunar highlands in the bottom of the image. The landing sides of the Apollo 12,14 and 15 missions lie within the central part of the image. Samples returned from these sites will be used to calibrate this and accompanying images taken in different colors, which will extend the knowledge of the spectral and compositional properties of the near side of the moon, seen from Earth, to the lunar far side. |
| Date |
12/8/90 |
|
A91-2018
Photographer: JPL This image
…
3/21/94
| Description |
Photographer: JPL This image is the first full picture showing both asteroid 243 Ida and its newly discovered moon to be transmitted to Earth from NASA's Galileo spacecraft--the first conclusive evidence that natural satellites of asteroids exist. Ida is the large object to the left, about 56 kilometers (35 miles long). Ida's natural satellite is the small object to the right. This portrait was taken by Galileo's charge-coupled device (CCD) camera on August 28, 1993, about 14 minutes before the spacecraft's closest approach to the asteriod, from a range of 10,870 kilometers (6,755 miles). Ida is a heavily cratered, irregularly shaped asteroid in the main asteroid belt between Mars and Jupiter-- the 243rd asteroid to be discovered since the first one was found at the beginning of the 19th century. It is a member of a group of asteroids called the Koronis family. The small satellite, which is about 1.5 kilometers (1 mile) across in this view, has yet to be given a name by astronomers. It has been provisionally designated "1993 (243) 1" by the International Astronomical Union. (The numbers denote the year the picture was taken, the asteroid number and the fact that it is the first moon of Ida to be found.) ALthough the satellite appears to be "next" to Ida it is actually slightly in the foreground, closer to the spacecraft than Ida. Combining this image with data from Galileo's near-infrared mapping spectrometer, the science team estimates that the object is about 100 kilometers (60 miles) away from the center of Ida. This image is one of a six-frame series taken through different color filters, this one in green. The spatial resolution in this image is about 100 meters (330 feet) per pixel. The Galileo spacecraft flew past Ida en route to its final destination, Jupiter, where it will go into orbit in December 1995. The Jet Propulsion Laboratory manages the galileo Project for NASA's Office of Space Science. (JPL ref. No. P-43731) |
| Date |
3/21/94 |
|
The Largest Rock Known
| Title |
The Largest Rock Known |
| Explanation |
There, that faint dot in the center - that's the largest rock known. It is larger than every known asteroid [ http://www.seds.org/nineplanets/nineplanets/asteroids.html ], moon [ http://www.solarviews.com/eng/ganymede.htm ], and comet nucleus [ http://antwrp.gsfc.nasa.gov/apod/ap961210.html ]. It is larger than any other rocky planet [ http://antwrp.gsfc.nasa.gov/apod/ap960923.html ]. (Nobody knows for sure what size rocks lie at the cores of Jovian planets [ http://quest.arc.nasa.gov/galileo/index.html ], or orbit other stars.) The Voyager [ http://nssdc.gsfc.nasa.gov/planetary/voyager.html ] 1 spacecraft took this picture [ http://nssdc.gsfc.nasa.gov/photo_gallery/caption/solar_family.txt ] in 1990 from the outer Solar System [ http://antwrp.gsfc.nasa.gov/apod/ap980517.html ]. This rock is so large its gravity [ http://www.glenbrook.k12.il.us/gbssci/phys/Class/1DKin/U1L5b.html ] makes it nearly spherical, and holds heavy gases near its surface. Yesterday, this rock started another orbit around its parent star [ http://antwrp.gsfc.nasa.gov/apod/ap980830.html ], for roughly the 5 billionth time, spinning over 350 times during each trip. Happy Gregorian Calendar [ http://es.rice.edu/ES/humsoc/Galileo/Things/gregorian_calendar.html ] New Year to all the human inhabitants of this rock [ http://www.seds.org/billa/psc/pbd.html ] we call Earth [ http://antwrp.gsfc.nasa.gov/apod/ap990131.html ]. |
|
Sky and Planets
| Title |
Sky and Planets |
| Explanation |
On February 10th, an evocative [ http://www.jps.net/ssumner/ ] evening sky above Rocklin, California, USA inspired astrophotographer Steve Sumner to record this remarkable sight - five planets and the Moon. Near its first quarter phase, the bright Moon [ http://lunar.arc.nasa.gov/ ] was intentionally overexposed but Saturn [ http://www.jpl.nasa.gov/cassini/ ], Jupiter [ http://galileo.jpl.nasa.gov/ ], Mars [ http://mars.jpl.nasa.gov/ ], and Mercury [ http://sd-www.jhuapl.edu/MESSENGER/ ] (and, of course, planet Earth's [ http://www.earth.nasa.gov/ ] horizon) are all clearly visible in the deepening twilight. Notably absent in this grouping of naked-eye planets is Venus [ http://antwrp.gsfc.nasa.gov/apod/ap990903.html ] which is still putting in an early appearance as the morning star [ http://ispec.scibernet.com/station/morn_star.html ]. This month, Mercury has joined Venus in the dawn twilight while Saturn, Jupiter, and Mars still shine brightly in the western sky at nightfall [ http://www.skypub.com/sights/sights.shtml ] making another gorgeous close grouping with the crescent Moon [ http://www.inconstantmoon.com/ ]. |
|
Venus, Moon, and Neighbors
| Title |
Venus, Moon, and Neighbors |
| Explanation |
Rising before the Sun on February 2nd, astrophotographer [ http://pages.prodigy.net/pam.orman/JoeGallery.html ] Joe Orman anticipated [ http://pages.prodigy.net/pam.orman/JoeAlmanac2000.html ] this apparition of the bright morning star [ http://ispec.scibernet.com/station/morn_star.html ] Venus near a lovely crescent Moon above a neighbor's house in suburban Phoenix, Arizona, USA. Fortunately, the alignment of bright planets and the Moon is one of the most inspiring sights in the night sky [ http://www.skypub.com/sights/skyevents/0004skyevents.html ] and one that is often easy to enjoy and share without any special equipment. Take tonight [ http://spacescience.com/headlines/y2000/ast30mar_1m.htm ], for example. Those blessed with clear skies can simply step outside near sunset and view a young crescent Moon very near three bright planets in the west Jupiter [ http://galileo.jpl.nasa.gov/ ], Mars [ http://mars.jpl.nasa.gov/mgs/ ], and Saturn [ http://www.jpl.nasa.gov/cassini/ ]. Jupiter will be the unmistakable brightest star near the Moon with a reddish Mars just to Jupiter's north and pale yellow Saturn directly above. Of course, these sky shows [ http://drumright.ossm.edu/astronomy/conjunctions.html ] create an evocative picture [ http://antwrp.gsfc.nasa.gov/apod/ap000310.html ] but the planets and Moon just appear to be near each other -- they are actually only approximately lined up and lie in widely separated orbits. Unfortunately, next month's highly publicized alignment of planets [ http://www.griffithobs.org/SkyAlignments.html ] on May 5th will be lost from view in the Sun's glare but such planetary alignments [ http://www.skypub.com/news/special/whypanic.html ] occur repeatedly and pose no danger [ http://www.badastronomy.com/bad/misc/planets.html ] to planet Earth. |
|
A Continuous Eruption on Jup
…
| Title |
A Continuous Eruption on Jupiter's Moon Io |
| Explanation |
A volcano on Jupiter's moon Io [ http://www.seds.org/nineplanets/nineplanets/io.html ] has been photographed recently during an ongoing eruption. Hot glowing lava is visible on the left on this representative-color image [ http://photojournal.jpl.nasa.gov/cgi-bin/PIAGenCatalogPage.pl?PIA02550 ]. A glowing landscape of plateaus and valleys covered in sulfur [ http://pearl1.lanl.gov/periodic/elements/16.html ] and silicate rock [ http://windows.ivv.nasa.gov/cgi-bin/tour_def/glossary/silicate_rock.html ] surrounds the active volcano [ http://volcano.und.nodak.edu/vwdocs/planet_volcano/Io/Overview.html ]. Many features including several of the dark spots [ http://antwrp.gsfc.nasa.gov/apod/ap971110.html ] have evolved between February 2000, when the robot spacecraft Galileo [ http://www.jpl.nasa.gov/galileo/spacecraft.html ] currently orbiting Jupiter [ http://www.seds.org/nineplanets/nineplanets/jupiter.html ] took this picture, and November 1999. Io [ http://cass.jsc.nasa.gov/pub/research/outerp/io.html ] is slightly larger than Earth's Moon [ http://antwrp.gsfc.nasa.gov/apod/ap991108.html ] and is the closest large moon to Jupiter [ http://galileo.jpl.nasa.gov/jupiter/jupiter.html ]. The above image [ http://photojournal.jpl.nasa.gov/cgi-bin/PIAGenCatalogPage.pl?PIA02550 ] shows a region about 250 kilometers across. How the internal structure of Io [ http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1990Icar...85..309R ] creates these active volcanoes [ http://antwrp.gsfc.nasa.gov/apod/ap961027.html ] remains under investigation. |
|
Crater On Ice
| Title |
Crater On Ice |
| Explanation |
Impact craters are common on Earth's moon [ http://antwrp.gsfc.nasa.gov/apod/ap990326.html ] but on Jupiter's large ice moon Europa [ http://sse.jpl.nasa.gov/features/planets/jupiter/ europa.html ], they are very rare. Over time, both bodies have been subjected to an intense pounding [ http://antwrp.gsfc.nasa.gov/apod/ap990610.html ] by the solar system's formative debris [ http://www.jhuapl.edu/public/pr/000530.htm ], but geological activity on Europa's surface seems to have erased most of these impact scars. This false-color infrared image [ http://photojournal.jpl.nasa.gov/cgi-bin/ PIAGenCatalogPage.pl?PIA02561 ] from the Galileo spacecraft's NIMS instrument [ http://jumpy.igpp.ucla.edu/~nims/ ] shows a newly discovered crater on Europa as a light red ring feature near center surrounding a dark core. For scale, the dark core is about 29 kilometers in diameter. Only seven comparably [ http://antwrp.gsfc.nasa.gov/apod/ap970417.html ] large craters have now been identified on Europa's surface. Red colors in the image represent a relatively pure water ice [ http://www.glacier.rice.edu/invitation/1_icetypes.html ] composition while blue colors indicate that other minerals are present. The crater's central dark area may contain the remnants of the impacting body. The icy crust of Europa [ http://galileo.jpl.nasa.gov/moons/europa.html ] is of great interest, as evidence mounts [ http://galileo.jpl.nasa.gov/news/release/ press000110.html ] that it covers an ocean of liquid water, possibly providing suitable conditions for life. |
|
Other Worlds and HD 38529
| Title |
Other Worlds and HD 38529 |
| Explanation |
After the latest round of discovery announcements [ http://www.iau.org/ga24press/ ], the list of known worlds of distant suns [ http://www.spaceart.org/lcook/extrasol.html ] has grown to 50 [ http://www.spaceref.com/news/viewnews.html?id=200 ]. While extrasolar planet [ http://exoplanets.org/ ] discoveries are [ http://obswww.unige.ch/~udry/planet/planet.html ] sure to continue, none - so far [ http://sim.jpl.nasa.gov/ ] - points clearly to another planetary system like our own [ http://antwrp.gsfc.nasa.gov/apod/ap991229.html ]. Take, for example, the newly discovered parent [ http://antwrp.gsfc.nasa.gov/apod/ap990611.html ] star HD38529 [ http://www.obspm.fr/encycl/HD38529.html ]. Shining in Earth's night sky at 6th magnitude, this sun-like star lies 137 light-years away in the constellation Orion [ http://aibn47.astro.uni-bonn.de/~gallery/constellations/orion/ main.html ]. Like most of the known extrasolar planets [ http://www.obspm.fr/encycl/encycl.html ], HD38529's planet was discovered by detecting the telltale Doppler wobble [ http://exoplanets.org/doppler.html ] in the parent star's spectrum. The data reveal that this planet orbits once every 14.3 days at an average of only 0.13 times the Earth-Sun distance and has a minimum of 0.77 Jupiter masses (about 240 Earth masses). There is even evidence [ http://www.iau.org/ga24press/pr000807_3.html#1 ] in the wobble data that HD38529, and other stars with one known planet have additional massive planets orbiting them. In this dramatic artist's vision, HD38529 and its newfound world are viewed from the moon of another massive ringed planet [ http://antwrp.gsfc.nasa.gov/apod/ap000330.html ] orbiting farther out. The ringed planet's moon is imagined to have a thin atmosphere and a surface covered with icy sheets and ridges similar to those found on Jupiter's moon Europa [ http://galileo.jpl.nasa.gov/moons/europa.html ]. |
|
Folding Europa
| Title |
Folding Europa |
| Explanation |
Astypalaea Linea [ http://wwwflag.wr.usgs.gov/USGSFlag/Space/nomen/jupiter/ euroTOC.html ] on Jovian [ http://cfa-www.harvard.edu/iau/pressinfo/S1999J1.html ] ice moon Europa [ http://www.seds.org/nineplanets/nineplanets/ europa.html ] is the broad smooth region running through these images [ http://photojournal.jpl.nasa.gov/cgi-bin/ PIAGenCatalogPage.pl?PIA02960 ] recorded by the Galileo spacecraft in 1998. The pictures are different computer processed versions of the same mosaic -- on the left, small scale details have been enhanced while on the right, large scale features are emphasized. In both versions, the bold criss-crossing ridges [ http://antwrp.gsfc.nasa.gov/apod/ap981215.html ] believed to result from the upwelling of new material through cracks in the surface ice are apparent. But more easily seen on the right are recently recognized [ http://www.jhuapl.edu/public/pr/000810.htm ] gentle rises and dips, about 15 kilometers across, which likely formed as the icy surface was compressed by the addition of the new material. Further evidence [ http://adsabs.harvard.edu/cgi-bin/nph-bib_query? bibcode=2000LPI....31.1182P&db_key=AST&high=3899d8d98211881 ] that stress is folding Europa's [ http://galileo.jpl.nasa.gov/moons/europa.html ] surface is offered by the presence of smaller cracks and wrinkles more easily seen on the left. These span the width of the broad swells suggestive of anticlines and synclines [ http://www.educ.uvic.ca/Faculty/jtinney/earth%20science/ ESMain.html#fold ] familiar to geologists on planet Earth [ http://antwrp.gsfc.nasa.gov/apod/ap000420.html ]. Though ice covered [ http://spacescience.com/headlines/y2000/ ast22aug_1.htm ], the surface of Europa is thought to be geologically active, riding over a substantial ocean [ http://adsabs.harvard.edu/cgi-bin/nph-bib_query? bibcode=1998Natur.391..363C&db_key=AST&high=3899d8d98211557 ] of liquid water. |
|
North Pole Below
| Title |
North Pole Below |
| Explanation |
Orbiting over the north pole of planet Earth [ http://earthobservatory.nasa.gov/ ] on May 5, the MODIS instrument on-board the Terra spacecraft [ http://terra.nasa.gov/ ], recorded this view of the ice cap [ http://earthobservatory.nasa.gov/Newsroom/NewImages/ images.php3?img_id=4193 ] 700 kilometers below. A radial grid centered on the pole is shown on top of the approximately true color image where each pixel covers about one square kilometer. Frozen sea ice [ http://www.natice.noaa.gov/ ] appears whitish while open water or newly refrozen ice looks black. An impressive criss-crossing network of cracks in ice shifting above a liquid water ocean is visible, traced by the meandering dark lines. In fact, the dark network of cracks in the sea ice [ http://southport.jpl.nasa.gov/polar/iceinfo.html ] is reminiscent of another world in our solar system which may also harbor a liquid water ocean -- Jupiter's ice moon [ http://antwrp.gsfc.nasa.gov/apod/ap960813.html ] Europa [ http://galileo.jpl.nasa.gov/moons/europa.html ]. |
|
Oceans Under Jupiter's Moon
…
| Title |
Oceans Under Jupiter's Moon Ganymede? |
| Explanation |
The search for extraterrestrial [ http://www.seti.org/ ] life came back into our own Solar System [ http://www.seds.org/nineplanets/nineplanets/overview.html ] last week with the announcement [ http://www.jpl.nasa.gov/releases/2000/aguganymederoundup.html ] that there may be liquid oceans under the surface of Jupiter [ http://antwrp.gsfc.nasa.gov/apod/jupiter.html ]'s moon Ganymede [ http://www.jpl.nasa.gov/galileo/moons/ganymede.html ]. Ganymede [ http://antwrp.gsfc.nasa.gov/apod/ap000620.html ] now joins Callisto [ http://www.jpl.nasa.gov/galileo/news32.html ] and Europa [ http://www.jpl.nasa.gov/galileo/moons/europa.html ] as moons of Jupiter [ http://www.solarviews.com/eng/jupiter.htm ] that may harbor seas of liquid water under layers of surface ice [ http://antwrp.gsfc.nasa.gov/apod/ap980722.html ]. The ocean hypothesis surfaced as an explanation for Ganymede's unusually strong magnetic field [ http://www.igpp.ucla.edu/galileo/doc/n384/text.htm ]. Ganymede, the largest moon in the Solar System, also has the largest measured magnetic field [ http://www-spof.gsfc.nasa.gov/Education/Imagnet.html ] of any moon. Some exobiologists [ http://exobiology.nasa.gov/ssx/exobiology.html ] hypothesize that life may be able to emerge [ http://www.etext.org/Zines/Quanta/life.html ] in such an ocean, much as it did in the oceans of ancient Earth [ http://wwwcatsic.ucsc.edu/~eart1/Notes/Lec1.html ]. Above [ http://photojournal.jpl.nasa.gov/cgi-bin/PIAGenCatalogPage.pl?PIA02583 ], a frame from a computer simulation [ http://photojournal.jpl.nasa.gov/cgi-bin/PIAGenDownloadOpts.pl?PIA02583 ] shows what it would look like to fly over [ http://antwrp.gsfc.nasa.gov/apod/ap961025.html ] the surface of Ganymede, as extrapolated from photographs of the grooved moon [ http://antwrp.gsfc.nasa.gov/apod/ap960711.html ] taken by the robot spacecraft Galileo [ http://www.jpl.nasa.gov/galileo/mission.html ] currently orbiting Jupiter. |
|
Io: Moon Over Jupiter
| Title |
Io: Moon Over Jupiter |
| Explanation |
How big is the Jovian moon Io [ http://www.seds.org/nineplanets/ nineplanets/io.html ]? The most volcanic body [ http://volcano.und.nodak.edu/vwdocs/planet_volcano/ other_worlds.html ] in the Solar System, Io (usually pronounced "EYE-oh") is 3,600 kilometers in diameter, about the size of planet Earth's single large natural satellite [ http://antwrp.gsfc.nasa.gov/apod/ap010127.html ]. Gliding past Jupiter [ http://www.jpl.nasa.gov/jupiterflyby/ ] at the turn of the millennium, the Cassini spacecraft captured this awe inspiring view [ http://ciclops.lpl.arizona.edu/ciclops/images_jupiter.html ] of active Io [ http://www.jpl.nasa.gov/galileo/moons/io.html ] with the largest [ http://www.seds.org/nineplanets/nineplanets/ datamax.html ] gas giant as a backdrop, offering a stunning demonstration of the ruling planet's relative size [ http://nssdc.gsfc.nasa.gov/planetary/factsheet/ jupiterfact.html ]. Although in the picture Io [ http://photojournal.jpl.nasa.gov/cgi-bin/ PIAGenCatalogPage.pl?PIA02879 ] appears to be located just in front of the swirling Jovian clouds, Io hurtles around its orbit once every 42 hours at a distance of 420,000 kilometers or so from the center of Jupiter [ http://nssdc.gsfc.nasa.gov/planetary/factsheet/ joviansatfact.html ]. That puts it nearly 350,000 kilometers above Jupiter's cloud tops [ http://antwrp.gsfc.nasa.gov/apod/ap010215.html ], roughly equivalent to the distance between Earth and Moon [ http://antwrp.gsfc.nasa.gov/apod/ap980904.html ]. The Cassini spacecraft [ http://www.jpl.nasa.gov/cassini/english/spacecraft/ ] itself was about 10 million kilometers from Jupiter when recording the image data. |
|
Gibbous Europa
| Title |
Gibbous Europa |
| Explanation |
Although the phase [ http://antwrp.gsfc.nasa.gov/apod/ap010218.html ] of this moon might appear familiar, the moon itself might not. In fact, this gibbous phase [ http://en.wikipedia.org/wiki/Gibbous ] shows part of Jupiter [ http://www.nineplanets.org/jupiter.html ]'s moon Europa [ http://www.nineplanets.org/europa.html ]. The robot spacecraft Galileo [ http://en.wikipedia.org/wiki/ Galileo_%28spacecraft%29 ] captured this image [ http://planetimages.blogspot.com/2005/09/ new-color-views-of-europa.html ] mosaic during its mission orbiting Jupiter from 1995 - 2003. Visible are plains [ http://antwrp.gsfc.nasa.gov/apod/ap981215.html ] of bright ice [ http://antwrp.gsfc.nasa.gov/apod/ap000418.html ], cracks [ http://antwrp.gsfc.nasa.gov/apod/ap980310.html ] that run to the horizon, and dark patches [ http://antwrp.gsfc.nasa.gov/apod/ap970815.html ] that likely contain both ice and dirt. Raised terrain [ http://antwrp.gsfc.nasa.gov/apod/ap980303.html ] is particularly apparent near the terminator [ http://en.wikipedia.org/wiki/ Terminator_%28solar%29 ], where it casts shadows [ http://antwrp.gsfc.nasa.gov/apod/ap001225.html ]. Europa [ http://antwrp.gsfc.nasa.gov/apod/ap961120.html ] is nearly the same size as Earth's Moon [ http://antwrp.gsfc.nasa.gov/apod/ap020127.html ], but much smoother, showing few highlands [ http://csep10.phys.utk.edu/astr161/lect/moon/ moon_surface.html ] or large impact craters [ http://antwrp.gsfc.nasa.gov/apod/ap010809.html ]. Evidence and images from the Galileo spacecraft [ http://solarsystem.nasa.gov/galileo/ ], indicated that liquid oceans might exist [ http://antwrp.gsfc.nasa.gov/apod/ap980102.html ] below the icy surface. To test speculation that these seas hold life, ESA [ http://en.wikipedia.org/wiki/European_Space_Agency ] has started preliminary development of the Jovian Europa Orbiter [ http://www.jpl.nasa.gov/europaorbiter/europao.htm ], a spacecraft proposed to orbit Europa. If the surface ice is thin enough, a future mission might drop hydrobots [ http://www.jpl.nasa.gov/galileo/mission/ journey-future.html ] to burrow into the oceans and search for life. |
|
Ganymede: Torn Comet - Crate
…
| Title |
Ganymede: Torn Comet - Crater Chain |
| Explanation |
This striking line of 13 closely spaced craters [ http://photojournal.jpl.nasa.gov/cgi-bin/ PIAGenCatalogPage.pl?PIA01610 ] on Jupiter's moon Ganymede [ http://cass.jsc.nasa.gov/pub/research/outerp/gany.html ] was photographed by the Galileo spacecraft in 1997. The picture covers an area about 120 miles wide and the chain of craters cuts across a sharp boundary between dark and light terrain. What caused this crater chain? Remarkably, the exploration of the Solar System [ http://sse.jpl.nasa.gov/index.html ], has shown that crater chains [ http://antwrp.gsfc.nasa.gov/apod/ap950715.html ] like this one are not unique [ http://neo.jpl.nasa.gov/images/moon.html ], though they were [ http://stardust.jpl.nasa.gov/news/news12.html ] considered mysterious until a dramatic object lesson was offered by comet Shoemaker-Levy 9. In 1994 many denizens of planet Earth [ http://antwrp.gsfc.nasa.gov/apod/ap971026.html ] watched as huge pieces of this torn comet [ http://antwrp.gsfc.nasa.gov/apod/ap990814.html ] slammed into Jupiter itself in a spectacular series of sequential impacts [ http://antwrp.gsfc.nasa.gov/apod/ap980804.html ]. It is very likely that similar torn comets from the early history of the Solar System are responsible for this and other crater chains [ http://astrosun.tn.cornell.edu/staff/bottke/crater_chain/ chain.html ]. |
|
The Earth-Moon System
| Title |
The Earth-Moon System |
| Explanation |
A double planet? From 4 million miles away on December 16, 1992, NASA's robot spacecraft Galileo [ http://nssdc.gsfc.nasa.gov/planetary/galileo.html ] took this picture of the Earth-moon system. The bright, sunlit half of the Earth contrasts strongly with the darker subdued colors of the moon. Our moon is one of the largest moons in the solar system. It is even larger than the planet Pluto. In this picture, the Earth-moon system actually appears to be a double planet. For more information see NASA, Jet Propulsion Laboratory press release. [ http://nssdc.gsfc.nasa.gov/photo_gallery/caption/gal_earth_moon.txt ] |
|
Venus: Earth's Sister Planet
| Title |
Venus: Earth's Sister Planet |
| Explanation |
This picture in visible light was taken by the Galileo [ http://nssdc.gsfc.nasa.gov/planetary/galileo.html ] spacecraft. Venus [ http://seds.lpl.arizona.edu/nineplanets/nineplanets/venus.html ] is very similar to Earth [ http://antwrp.gsfc.nasa.gov/apod/ap950622.html ] in size and mass - and so is sometimes referred to as Earth's sister planet - but Venus has a quite different climate. Venus' [ http://www.c3.lanl.gov/~cjhamil/SolarSystem/venus.html ] thick clouds and closeness to the Sun [ http://antwrp.gsfc.nasa.gov/apod/ap950813.html ] (only Mercury [ http://antwrp.gsfc.nasa.gov/apod/ap950814.html ] is closer) make it the hottest planet - much hotter than the Earth. Humans could not survive there, and no life of any sort has ever been found. When Venus [ http://nssdc.gsfc.nasa.gov/photo_gallery/PhotoGallery-Venus.html ] is visible it is usually the brightest object in the sky after the Sun and the Moon. More than 20 spacecraft have visited Venus including Venera 9, which landed on the surface, and Magellan [ http://stardust.jpl.nasa.gov/mveg/guide.html ], which used radar to peer through the clouds and make a map of the surface. There are still many things about Venus's unusual atmosphere that astronomers don't understand. Tomorrow's picture: Uranus: The Tilted Planet |
|
Crescent Europa
| Title |
Crescent Europa |
| Explanation |
Although the phase [ http://antwrp.gsfc.nasa.gov/apod/ap010218.html ] of this moon might appear familiar, the moon itself might not. In fact, this crescent shows part of Jupiter [ http://www.nineplanets.org/jupiter.html ]'s moon Europa [ http://www.nineplanets.org/europa.html ]. The passing robot spacecraft Voyager 2 [ http://vraptor.jpl.nasa.gov/voyager/vgrfaqs.html ] captured this image [ http://grin.hq.nasa.gov/ABSTRACTS/GPN-2000-000469.html ] in 1979. Visible are plains [ http://antwrp.gsfc.nasa.gov/apod/ap981215.html ] of bright ice [ http://antwrp.gsfc.nasa.gov/apod/ap000418.html ], cracks [ http://antwrp.gsfc.nasa.gov/apod/ap980310.html ] that run to the horizon, and dark patches [ http://antwrp.gsfc.nasa.gov/apod/ap970815.html ] that likely contain both ice and dirt. Raised terrain [ http://antwrp.gsfc.nasa.gov/apod/ap980303.html ] is particularly apparent near the terminator [ http://calspace.ucsd.edu/edout/gloss/tgloss.html#terminator ], where it casts shadows [ http://antwrp.gsfc.nasa.gov/apod/ap001225.html ]. Europa [ http://antwrp.gsfc.nasa.gov/apod/ap961120.html ] is nearly the same size as Earth's Moon [ http://antwrp.gsfc.nasa.gov/apod/ap020127.html ], but much more smooth, showing few highlands [ http://csep10.phys.utk.edu/astr161/lect/moon/moon_surface.html ] or large impact craters [ http://antwrp.gsfc.nasa.gov/apod/ap010809.html ]. Evidence and images from the Galileo spacecraft [ http://galileo.jpl.nasa.gov/mission/space-intro.html ], currently orbiting Jupiter [ http://galileo.jpl.nasa.gov/mission/mission.html ], indicate that liquid oceans might exist [ http://antwrp.gsfc.nasa.gov/apod/ap980102.html ] below the icy surface. To test speculation that these seas hold life, NASA [ http://www.nasa.gov/ ] has started preliminary development of the Europa Orbiter [ http://www.jpl.nasa.gov/europaorbiter/europao.htm ], a spacecraft that would use radar [ http://www.howstuffworks.com/radar.htm ] to help determine the thickness of the surface ice. If the surface ice is thin enough, a future mission might drop hydrobots [ http://www.jpl.nasa.gov/galileo/mission/journey-future.html ] to burrow into the oceans and search for life. |
|
Ganymede: Moonquake World
| Title |
Ganymede: Moonquake World |
| Explanation |
Ganymede [ http://seds.lpl.arizona.edu/nineplanets/nineplanets/ganymede.html ] probably undergoes frequent ground shaking events not unlike terrestrial earthquakes. Ganymede [ http://www.c3.lanl.gov/~cjhamil/SolarSystem/ganymede.html ], the largest moon of Jupiter [ http://antwrp.gsfc.nasa.gov/apod/ap950625.html ] and the Solar System [ http://antwrp.gsfc.nasa.gov/apod/ap950819.html ], has a thick outer coating of water ice. Passing Voyager spacecraft found a large number of cracks and grooves in the ice so it is thought that Ganymede, like the Earth [ http://antwrp.gsfc.nasa.gov/apod/ap950622.html ], has large shifting surface masses called tectonic plates. Ganymede was discovered by Galileo [ http://galileo.imss.firenze.it/museo/4/index.html ] and Marius [ http://seds.lpl.arizona.edu/billa/tnp/help.html#M ] in 1610, and is larger than the planets Mercury and Pluto. The NASA spacecraft Galileo [ http://www.jpl.nasa.gov/galileo/ ] is scheduled to arrive at Jupiter is December of 1995. Tomorrow's picture: Europa: Ancient Water World |
|
Europa: Ancient Water World
| Title |
Europa: Ancient Water World |
| Explanation |
Beneath the cold icy surface of Jupiter [ http://antwrp.gsfc.nasa.gov/apod/ap950625.html ]'s moon Europa [ http://seds.lpl.arizona.edu/nineplanets/nineplanets/europa.html ] are probably the only oceans of water in our Solar System [ http://antwrp.gsfc.nasa.gov/apod/ap950819.html ] outside of Earth [ http://antwrp.gsfc.nasa.gov/apod/ap950622.html ]. These oceans, possibly 50 kilometers deep, might also be the most likely local place to find extra-terrestrial life. Europa [ http://www.c3.lanl.gov/~cjhamil/SolarSystem/europa.html ]'s smooth surface is unlike any other known planet or moon, giving evidence for relatively few craters or mountains. Europa was discovered by Galileo [ http://galileo.imss.firenze.it/museo/4/index.html ] and Marius [ http://seds.lpl.arizona.edu/billa/tnp/help.html#M ] in 1610. The NASA spacecraft Galileo [ http://www.jpl.nasa.gov/galileo/ ] is scheduled to arrive at Jupiter in December of 1995. Tomorrow's picture: Callisto: Dark Smashed Iceball |
|
|
