EARTH FROM STARS, WACHING THE SKY

Death Valley National ParkAt 86 meters (282 feet) below sea level, Death Valley, California, is one of the hottest, driest places on the planet. On average, the area sees only about 5 centimeters (1.96 inches) of rain a year, and summer temperatures routinely soar above 38 degrees Celsius (100 degrees Fahrenheit). At night, temperatures drop considerably, and many animals in Death Valley are nocturnal as a result. Plants and animals living in this punishing environment have had to adapt to extremes of temperature and aridity.

This image is compiled from observations by the Enhanced Thematic Mapper Plus sensor on the Landsat 7 satellite on June 11 and July 20, 2000. In this image, green indicates vegetation, which increases with altitude. The peaks of Death Valley National Park sport forests of juniper and pine. The dots of brilliant green near the right edge of the image fall outside park boundaries, and probably result from irrigation. On the floor of the valley, vegetation is sparse, yet more than 1,000 different species eke out an existence in the park, some of them sending roots many feet below ground. The varying shades of brown, beige and rust indicate bare ground; the different colors result from varying mineral compositions in the rocks and dirt. Although they appear to be pools of water, the bright blue-green patches in the scene are actually salt pans that hold only a little moisture. Image credit: NASA

Fountains of EnceladusRecent Cassini images of Saturn's moon Enceladus backlit by the sun show the fountain-like sources of the fine spray of material that towers over the south polar region. The image was taken looking more or less broadside at the "tiger stripe" fractures observed in earlier Enceladus images. It shows discrete plumes of a variety of apparent sizes above the limb of the moon.

Image credit: NASA/JPL-Caltech

Dust in the Quasar WindDusty grains - including tiny specks of the minerals found in the gemstones peridot, sapphires and rubies - can be seen blowing in the winds of a quasar, or active black hole, in this artist's concept. Astronomers using NASA's Spitzer Space Telescope found evidence that such quasar winds might have forged these dusty particles in the very early universe. Dust is crucial for efficient star formation as it allows the giant clouds where stars are born to cool quickly and collapse into new stars. Dust has been seen as far back as when the universe was less than a tenth of its current age, but how did it get there?

Image credit: NASA/JPL-Caltech

Birth of a PlanetThis artist's conception shows binary-star system HD 113766, where astronomers suspect a rocky Earth-like planet is forming around one of the stars. At approximately 10-16 million years old, astronomers suspect this star is at just the right age for forming rocky planets.

The brown ring of material circling closest to the central star depicts a huge belt of dusty material, more than 100 times as much as in our asteroid belt, or enough to build a asteroid belt, or enough to build a Mars-size planet or larger. The rocky material in the belt represents the early stages of planet formation, when dust grains clump together to form rocks, and rocks collide to form even more massive rocky bodies called planetesimals. The belt is located in the middle of the system's terrestrial habitable zone, or the region around a star where liquid water could exist on any rocky planets that might form. Earth is located in the middle of our sun's terrestrial habitable zone. The white outer ring shows a concentration of icy dust also detected in the system. This material is at the equivalent position of the asteroid belt in our solar system, but only contains about one-sixth as much material as the inner ring. Astronomers say it is not clear from the Spitzer observations if anything is occurring in the icy belt, but they believe it could be a source of water for the planet that grows from the inner warm ring. Image credit: NASA/JPL-Caltech

This 1992 photo shows an F-16 Scamp model being tested in the Basic Aerodynamics Research Tunnel or BART, at NASA's Langeley Research Center. The photo shows a basic flow visualization test using smoke and a laser light sheet to illuminate the smoke. The testing took place as part of NASA's High Speed Research Program.

Image credit: NASA

Natal MicrocosmIn the quest to better understand the birth of stars and the formation of new worlds, astronomers have used NASA's Spitzer Space Telescope to examine the massive stars contained in a cloudy region called Sharpless 140. This cloud is a star-forming microcosm that exhibits, within a relatively small area, all of the classic manifestations of stellar birth.

Sharpless 140 lies almost 3,000 light-years from Earth in the constellation Cepheus. At its heart is a cluster of three deeply embedded young stars, which are each several thousand times brighter than the sun. Though they are strikingly visible in this image from Spitzer's infrared array camera, they are completely obscured in visible light, buried within the core of the surrounding dust cloud.

The extreme youth of at least one of these stars is indicated by the presence of a stream of gas moving at high velocities. Such outflows are signatures of the processes surrounding a star that is still gobbling up material as part of its formation.

The bright red bowl, or arc, seen in this image traces the outer surface of the dense dust cloud encasing the young stars. This arc is made up primarily of organic compounds called polycyclic aromatic hydrocarbons, which glow on the surface of the cloud. Ultraviolet light from a nearby bright star outside of the image is "eating away" at these molecules. Eventually, this light will destroy the dust envelope and the masked young stars will emerge.

Image credit: NASA/GSFC/METI/ERSDAC/JAROS

Esperanza FireThe Esperanza Fire started on Oct. 26 in the dry brush near Palm Springs, Calif. By the time it was contained 6 days later, the arson fire had consumed 40,200 acres, and destroyed 34 homes and 20 outbuildings. Racing through grass, brush and timber, the blaze killed five firefighters and forced hundreds to evacuate. In this ASTER image composite of visible and infrared bands, burned areas are shown in shades of red, vegetation is green, brown vegetation is brown and asphalt and concrete are blue-gray.

With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER images Earth to map and monitor the changing surface of our planet.

The broad spectral coverage and high spectral resolution of ASTER provides scientists with critical information for surface mapping, and monitoring of dynamic conditions and temporal change. Applications include monitoring glacial advances and retreats; monitoring potentially active volcanoes; identifying crop stress; evaluating wetlands; and, monitoring thermal pollution monitoring.

Image credit: NASA/GSFC/METI/ERSDAC/JAROS and U.S./Japan ASTER Science Team

Chaos at the Heart of OrionNASA's Spitzer and Hubble Space Telescopes teamed up to expose the chaos that baby stars are creating 1,500 light years away in a cosmic cloud called the Orion nebula. This striking composite indicates that four monstrously massive stars, collectively called the "Trapezium," at the center of the cloud may be the main culprits in the Orion constellation, a familiar sight in the fall and winter night sky in the northern hemisphere. Their community can be identified as the yellow smudge near the center of the image.

Swirls of green in Hubble's ultraviolet and visible-light view reveal hydrogen and sulfur gas that have been heated and ionized by intense ultraviolet radiation from the Trapezium's stars. Meanwhile, Spitzer's infrared view exposes carbon-rich molecules called polycyclic aromatic hydrocarbons in the cloud. These organic molecules have been illuminated by the Trapezium's stars, and are shown in the composite as wisps of red and orange. On Earth, polycyclic aromatic hydrocarbons are found on burnt toast and in automobile exhaust.

Stellar winds from clusters of newborn stars scattered throughout the cloud etched all of the well-defined ridges and cavities in Orion. The large cavity near the right of the image was most likely carved by winds from the Trapezium's stars. Located 1,500 light-years away from Earth, the Orion nebula is the brightest spot in the sword of the Orion, or the "Hunter" constellation. The cosmic cloud is also our closest massive star-formation factory, and astronomers believe it contains more than 1,000 young stars. Image credit: NASA/JPL-Caltech/STScI

Cygnus Loop Supernova RemnantThis 1991 image from NASA's Hubble Space Telescope captures a small section of the Cygnus Loop supernova remnant. The Cygnus Loop marks the edge of a bubble-like, expanding blast wave from a colossal stellar explosion which occurred about 15,000 years ago. Supernova remnants play an important role in stellar evolution by enriching space with heavy elements, and triggering new star formation by compressing interstellar gas.

The image shows the structure behind the shock waves in the Cygnus Loop with unprecedented clarity, allowing astronomers to compare directly the actual structure of the shock with theoretical model calculations for the first time. Besides supernova remnants, these shock models are important in understanding a wide range of astrophysical phenomena, ranging from winds in newly-formed stars to cataclysmic stellar outbursts.

As the supernova blast wave slams into tenuous clouds of interstellar gas, the resulting collision heats and compresses the gas, causing it to glow. The shock acts as a searchlight by revealing the structure of the interstellar medium.

A bluish ribbon of light stretching left to right across the picture might be a knot of gas ejected by the supernova. This interstellar "bullet," traveling over three million miles per hour (5 million km), is just catching up with the shock front, which has been slowed by plowing into interstellar material.

The Cygnus Loop appears as a faint ring of glowing gases about three degrees across (six times the diameter of the full moon), located in the northern constellation Cygnus the Swan. The supernova remnant is within the plane of our Milky Way Galaxy and is 2,600 light-years away.

Image credit: NASA and J.J. Hester (Arizona State University)

Black Widow Nebula Hides in the DustIn this Spitzer image, the two opposing bubbles are being formed in opposite directions by the powerful outflows from massive groups of forming stars. The baby stars can be seen as specks of yellow where the two bubbles overlap.

When individual stars form from molecular clouds of gas and dust they produce intense radiation and very strong particle winds. Both the radiation and the stellar winds blow the dust outward from the star creating a cavity or bubble.

In the case of the Black Widow Nebula, astronomers suspect that a large cloud of gas and dust condensed to create multiple clusters of massive star formation. The combined winds from these groups of large stars probably blew out bubbles into the direction of least resistance, forming a double bubble.

Image credit: NASA/JPL-Caltech/Univ. of Wisc.

Cone NebulaResembling a nightmarish beast rearing its head from a crimson sea, this monstrous object is actually a pillar of gas and dust. Called the Cone Nebula because of its conical shape in ground-based images, this giant pillar resides in a turbulent star-forming region. Taken by the Hubble Space Telescope in April 002, this image shows the upper 2.5 light-years of the nebula, a height that equals 23 million round trips to the moon. The entire nebula is 7 light years in length. The Cone Nebula resides 2,500 light-years away in the constellation Monoceros.

Radiation from hot, young stars has slowly eroded the nebula over millions of years. Ultraviolet light heats the edges of the dark cloud, releasing gas into the relatively empty region of surrounding space. There, additional ultraviolet radiation causes the hydrogen gas to glow, which produces the red halo of light seen around the pillar. A similar process occurs on a much smaller scale to gas surrounding a single star, forming the bow-shaped arc seen near the upper left side of the Cone. This arc is 65 times larger than the diameter of our solar system. The blue-white light from surrounding stars is reflected by dust. Background stars can be seen peeking through the evaporating tendrils of gas, while the turbulent base is pockmarked with stars reddened by dust. Over time, only the densest regions of the Cone will be left. Inside these regions, stars and planets may form.

The Cone Nebula is a cousin of the M16 pillars, which the Hubble imaged in 1995. Monstrous pillars of cold gas like the Cone and M16 are common in large regions of star birth. Astronomers believe the pillars are incubators for developing stars.

Image credit: NASA, H. Ford (JHU), G. Illingworth (UCSC/LO), M. Clampin (STScI), G. Hartig (STScI), the ACS Science Team and ESA

Supernova RemnantIn the nearby galaxy known as the Small Magellanic Cloud, a massive star has exploded as a supernova and begun to dissipate its interior into a spectacular display of colorful filaments, reminiscent of fireworks display.

The supernova remnant (SNR), known as "E0102" for short, is the greenish-blue shell of debris just below the center of this image from NASA's Hubble Space Telescope. This delicate structure, glowing a multitude of lavenders and peach hues, resides in the upper right of the image.

Determined to be only about 2,000 years old, E0102 is relatively young on astronomical scales and is just beginning its interactions with the nearby interstellar medium. Young supernova remnants like E0102 allow astronomers to examine material from the cores of massive stars directly. This in turn gives insight on how stars form, their composition, and the chemical enrichment of the surrounding area. As well, young remnants are a great learning tool to better understand the physics of supernova explosions.

The Small Magellanic Cloud is a nearby dwarf galaxy to our own Milky Way. It is visible in the Southern Hemisphere, in the direction of the constellation Tucana, and lies roughly 210,000 light-years distant.

Image credit: NASA, ESA, the Hubble Heritage Team (STScI/AURA) and J. Green (University of Colorado, Boulder)

Ring Holds a Delicate FlowerNASA's Spitzer Space Telescope finds a delicate flower in the Ring Nebula, as shown in this image. The outer shell of this planetary nebula looks surprisingly similar to the delicate petals of a camellia blossom. (A planetary nebula is a shell of material ejected from a dying star.) Located about 2,000 light years from Earth in the constellation Lyra, the Ring Nebula is also known as Messier Object 57 and NGC 6720. It is one of the best examples of a planetary nebula and a favorite target of amateur astronomers.

The "ring" is a thick cylinder of glowing gas and dust around the doomed star. As the star begins to run out of fuel, its core becomes smaller and hotter, boiling off its outer layers. Spitzer's infrared array camera detected this material expelled from the withering star. Previous images of the Ring Nebula taken by visible-light telescopes usually showed just the inner glowing loop of gas around the star. The outer regions are especially prominent in this new image because Spitzer sees the infrared light from hydrogen molecules. The molecules emit the infrared light that they have absorbed ultraviolet radiation from the star or have been heated by the wind from the star.

Image credit: NASA/JPL-Caltech/Harvard-Smithsonian CfA

String of PearlsSaturn's fascinating meteorology manifests itself as a "string of pearls" formation, spanning more than 60,000 kilometers (37,000 miles).

Seen in new images acquired by Cassini's visual and infrared mapping spectrometer and lit from below by Saturn's internal thermal glow, the bright "pearls" are actually clearings in Saturn's deep cloud system. More than two dozen occur at 40 degrees north latitude. Each clearing follows another at a regular spacing of some 3.5 degrees in longitude.

This is the first time such a regular and extensive train of cloud-clearings has been observed. The regularity indicates that they may be a manifestation of a large planetary wave. Scientists plan to take more observations of this phenomenon over the next few years to try to understand Saturn's deep circulation systems and meteorology. This image was taken on April 27, 2006.

Image credit: NASA/JPL/University of Arizona

Saturn's Silhouetted CloudsThis false-color mosaic shows deep-level clouds silhouetted against Saturn's glowing interior. This mosaic shows the entire planet, including features like Saturn's ring shadows and the terminator, the boundary between day and night.

The blue-green color (lower right) is sunlight scattered off clouds high in Saturn's atmosphere and the red color (upper left) is the glow of thermal radiation from Saturn's warm interior, easily seen on Saturn's night side (top left), within the shadow of the rings, and with somewhat less contrast on Saturn's day side (bottom right). The darker areas within Saturn show the strongest thermal radiation. The bright red color indicates areas where Saturn's atmosphere is relatively clear. The great variety of cloud shapes and sizes reveals a surprisingly active planet below the overlying sun-scattering haze.

The brighter glow of the northern hemisphere versus the southern indicates that the clouds and hazes there are noticeably thinner than those in the south. Scientists speculate that this is a seasonal effect, and if so, it will change as the northern hemisphere enters springtime during the next few years.

The data were obtained in February 2006 at a distance of 1.6 million kilometers (1 million miles) from directly over the plane of Saturn's rings, which appear here as a thin, blue line over the equator.

Image credit: NASA/JPL/University of Arizona

A Bird's-Eye View of ErebusThis false-color view combines frames taken by the panoramic camera on NASA's Mars Exploration Rover Opportunity on the rover's 652 through 663 Martian days, or sols (Nov. 23 to Dec. 5, 2005), at the edge of Erebus Crater. The mosaic is presented as a vertical projection. This type of projection provides a true-to-scale overhead view of the rover deck and nearby surrounding terrain. The view here shows outcrop rocks, sand dunes, and other features out to a distance of about 25 meters (82 feet) from the rover. Opportunity examined targets on the outcrop called "Rimrock" in front of the rover, testing the mobility and operation of Opportunity's robotic arm. The view shows examples of the dunes and ripples that Opportunity has been crossing as the rover drives on the Meridiani plains.

Image credit: NASA/JPL-Caltech/Cornell

Orbiting a Red Dwarf StarThis artist's concept of a gas giant planet orbiting a red dwarf K star shows a planet has not been directly imaged, but its presence was detected in 2003 microlensing observations of a field star in our galaxy. Gravitational microlensing happens when a foreground star amplifies the light of a background star that momentarily aligns with it. Follow-up observations by Hubble Space Telescope in 2005 separated the light of the slightly offset foreground star from the background star. This allowed the host star to be identified as a red dwarf star located 19,000 light-years away. The Hubble observations allow for the planet's mass to be estimated at 2.6 Jupiter masses. The characteristics of the lensing event show that the planet is in a Jupiter-sized orbit around its parent red star. The rings and moon around the gas giant are hypothetical, but plausible, given the nature of the family of gas giant planets in our solar system.

Image credit: NASA,ESA and G. Bacon (STScI)

An Unwelcome Place for New StarsThis artist's concept depicts a supermassive black hole at the center of a galaxy. NASA's Galaxy Evolution Explorer found evidence that black holes -- once they grow to a critical size -- stifle the formation of new stars in elliptical galaxies. Black holes are thought to do this by heating up and blasting away the gas that fuels star formation.

The blue color here represents radiation pouring out from material very close to the black hole. The grayish structure surrounding the black hole, called a torus, is made up of gas and dust. Beyond the torus, only the old red-colored stars that make up the galaxy can be seen. There are no new stars in the galaxy.

Image credit: NASA/JPL-Caltech

Stellar NurseryNASA's Spitzer Space Telescope captured a glowing stellar nursery within a dark globule that reveals the birth of new protostars, or embryonic stars, and young stars never before seen.

The Elephant's Trunk Nebula is an elongated dark globule within the emission nebula IC 1396 in the constellation of Cepheus. Within the globule, a half dozen newly discovered protostars are easily discernible as the bright red-tinted objects, mostly along the southern rim of the globule. These were previously undetected at visible wavelengths due to obscuration by the thick cloud ('globule body') and by dust surrounding the newly forming stars. The newborn stars form in the dense gas because of compression by the wind and radiation from a nearby massive star (located outside the field of view to the left). The winds from this unseen star are also responsible for producing the spectacular filamentary appearance of the globule itself, which resembles that of a flying dragon.

Image credit: NASA/JPL-Caltech/W. Reach (SSC/Caltech

The Face of PhoebePhoebe's true nature is revealed in startling clarity in this mosaic of two images taken during Cassini's flyby on June 11, 2004. This image of Saturn’s moon shows evidence for the emerging view that Phoebe may be an ice-rich body coated with a thin layer of dark material. Small bright craters in the image are probably fairly young features. This phenomenon has been observed on other icy satellites, such as Jupiter’s Ganymede.

When impactors slammed into the surface of Phoebe, the collisions excavated fresh, bright material -- probably ice -- underlying the surface layer. Further evidence for this can be seen on some crater walls where the darker material appears to have slid downwards, exposing more light-colored material. Some areas of the image that are particularly bright -- especially near lower right -- are over-exposed.

Image credit: NASA/JPL/Space Science Institute

The Plane of the EclipticThe Plane of the Ecliptic is illustrated in this Clementine star tracker camera image which reveals (from right to left) the Moon lit by Earthshine, the sun's corona rising over the Moon's dark limb and the planets Saturn, Mars and Mercury.

The ecliptic plane is defined as the imaginary plane containing the Earth's orbit around the sun. In the course of a year, the sun's apparent path through the sky lies in this plane. The planetary bodies of our solar system all tend to lie near this plane, since they were formed from the sun's spinning, flattened, proto-planetary disk.

This image captures a momentary line-up looking out along this fundamental plane of our solar system.

Image credit: NASA

Flaming StarThis is a false-color image of the star AE Aurigae (bright source of light near the center of image) embedded in a region of space containing smoke-like filaments of carbon-rich dust grains. Such dust might be hiding deuterium, an isotope of hydrogen, and stymieing astronomers' efforts to study star and galaxy formation. NASA's Far Ultraviolet Spectroscopic Explorer (FUSE) satellite has surveyed the local deuterium concentration in the galaxy and found far more than expected. Because deuterium is a tracer of star and galaxy evolution, this discovery has the potential to radically alter theories about how stars and galaxies form.

Image credit: T.A. Rector and B.A. Wolpa, NOAO, AURA and NSF

Portrait of a Dying StarThe Bug Nebula, NGC 6302, is one of the brightest and most extreme planetary nebulae known. A blanket of icy hailstones at its center shrouds the fiery, dying star.

This image, taken by the NASA Hubble Wide Field Plantery Camera 2, shows impressive walls of compressed gas, laced with trailing strands and bubbling outflows.

Image credit: NASA, ESA and A. Zijlstra (UMIST, Manchester, UK)

Crab NebulaThis composite image of the Crab Nebula shows x-ray (blue) and optical (red) superimposed.

Image credit: NASA/HST/CXC/ASU/J. Hester et al.

Cocoon of a New White DwarfLike a butterfly, a white dwarf star begins its life by casting off the cocoon that enclosed it.

In the cocoon-like structure above, the planetary nebula designated NGC 2440, contains one of the hottest white dwarfs known to scientists. The white dwarf can be seen as the bright dot near the photo's center. Our sun eventually will become a "white dwarf butterfly," but not for another 5 billion years.

Image credit: NASA/R. Ciardullo (PSU)/H. Bond (STScI)

Solimões and Negro RiversThe largest river on the planet, the Amazon, forms from the confluence of the Solimões (the upper Amazon River) and the Negro at the Brazilian city of Manaus in central Amazonas. At the river conjunction, the muddy, tan-colored waters of the Solimões meet the "black" water of the Negro River. The unique mixing zone where the waters meet extends downstream through the rainforest for hundreds of miles, and attracts tourists from all over the world, which has contributed to substantial growth in the city of Manaus. It is the vast quantity of sediment eroded from the Andes Mountains that gives the Solimões its tan color. By comparison, water in the Negro derives from the low jungles where reduced physical erosion of rock precludes mud entering the river. In place of sediment, organic matter from the forest floor stains the river the color of black tea. The Solimões provides nutrient-rich mud to lakes on the floodplain (lower right). The ecology of muddy lakes differs correspondingly from that of nutrient-poor, blackwater rivers and lakes. Solimões water can be seen leaking into the Negro west of the main meeting zone (lower left). The Solimões is much shallower than the Negro because it has filled its valley and bed with great quantities of sediment since the valleys were excavated. Widths of the rivers differ for this reason. Image credit: NASA

Extreme PlanetsThis artist's concept depicts the pulsar planet system discovered by Aleksander Wolszczan in 1992. Wolszczan used the Arecibo radio telescope in Puerto Rico to find three planets - the first of any kind ever found outside our solar system - circling a pulsar named PSR B1257+12. Pulsars are rapidly rotating neutron stars, which are the collapsed cores of exploded massive stars. They spin and pulse with radiation, much like a lighthouse beacon. Here, the pulsar's twisted magnetic fields are highlighted by the blue glow. All three pulsar planets are shown in this picture; the farthest two from the pulsar (closest in this view) are about the size of Earth. Radiation from charged pulsar particles would probably rain down on the planets, causing their night skies to light up with auroras similar to our Northern Lights. One such aurora is illustrated on the planet at the bottom of the picture. Since this landmark discovery, more than 160 extrasolar planets have been observed around stars that are burning nuclear fuel. The planets spotted by Wolszczan are still the only ones around a dead star. They also might be part of a second generation of planets, the first having been destroyed when their star blew up. The Spitzer Space Telescope's discovery of a dusty disk around a pulsar might represent the beginnings of a similarly "reborn" planetary system. Image Credit: NASA/JPL-Caltech

Tadpole's Tidal TailIn this stunning vista recorded with the Hubble Space Telescope's Advanced Camera for Surveys, distant galaxies form a dramatic backdrop for disrupted spiral galaxy Arp 188, the Tadpole Galaxy. The cosmic tadpole is a mere 420 million light-years distant toward the northern constellation Draco. Its eye-catching tail is about 280 thousand light-years long and features massive, bright blue star clusters.

Scientists believe that a more compact intruder galaxy crossed in front of Arp 188 - from left to right in this view - and was slung around behind the Tadpole via gravitational attraction. During the close encounter, tidal forces drew out the galaxy’s stars, gas, and dust forming the spectacular tail. The intruder galaxy itself, estimated to lie about 300 thousand light-years behind the Tadpole, can be seen through foreground spiral arms at the upper left. Like its terrestrial namesake, the Tadpole Galaxy will likely lose it tail as it grows older, the tail's star clusters forming smaller satellites of the large spiral galaxy.

Image Credit: NASA

Perspective Image of the Virgin IslandsSt. Thomas, St. John, Tortola and Virgin Gorda are the four main islands (front to back) of this east-looking view of the U.S. and British Virgin Islands, along the northeast perimeter of the Caribbean Sea. For this view, a nearly cloud-free Landsat image was draped over elevation data from the Shuttle Radar Topography Mission (SRTM), and shading derived from the SRTM data was added to enhance the topographic expression.

Elevation is shown with 1.5x scaled vertical exaggeration. Coral reefs fringe the islands in many locations and appear as very light shades of blue. Tropical vegetation appears green, and developed areas appear in shades of brown and white.

As in much of the world, topography is the primary factor in the pattern of land use development in the Virgin Islands. Topography across most of the islands is quite rugged, and although the steep slopes create a scenic setting, they crowd most development into the small areas of low relief terrain, generally along the shoreline. The topographic pattern also affects water supply, wastewater disposal, landfill locations, road construction, and most other features of the development infrastructure. Additionally, topography defines the natural drainage pattern, which is the major consideration in anticipating tropical storm water runoff dangers, as well as the dangers of heightened sediment impacts upon the adjacent coral reefs. Image Credit: NASA/JPL/NIMA/SRTM Team

Cosmic TornadoLight-years in length, this cosmic tornado is actually a powerful jet cataloged as HH (Herbig-Haro) 49/50. Though such energetic outflows are well known to be associated with the formation of young stars, the exact cause of the spiraling structures apparent in this case is still mysterious. The embryonic star responsible for the 62 mile per second jet is located just off the top of the picture, while the bright star seen near the tip of the jet may just by chance lie along the line of sight. HH49/50 is about 450 light-years distant, located in the Chamaeleon I molecular cloud.

Image Credit: NASA/JPL-Caltech/J. Bally (Univ. of Colorado) et al.

Atacama Desert, ChileVivid colors belie the arid landscape of northern Chile where the Atacama Desert, one of the world’s driest, meets the foothills of the Andes. Here salt pans and gorges choked with mineral-streaked sediments give way to white-capped volcanoes.

This scene was acquired by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) instrument on NASA's Terra satellite on Oct. 28, 2001.

Image Credit: NASA/USGS

Eyes in the SkyThese shape-shifting galaxies have taken on the form of a giant mask. The icy blue eyes are actually the cores of two merging galaxies, called NGC 2207 and IC 2163, and the mask is their spiral arms. The false-color image consists of infrared data from NASA's Spitzer Space Telescope (red) and visible data from NASA's Hubble Space Telescope (blue/green).

NGC 2207 and IC 2163 met and began a sort of gravitational tango about 40 million years ago. The two galaxies are tugging at each other, stimulating new stars to form. Eventually, this cosmic ball will come to an end, when the galaxies meld into one. The dancing duo is located 140 million light-years away in the Canis Major constellation.

Image Credit: NASA/JPL-Caltech/STScI/Vassar

Augustine Volcano, AlaskaSince the spring of 2005, the U.S. Geological Survey's Alaska Volcano Observatory has detected increasing volcanic unrest at Augustine Volcano in Cook Inlet, Alaska, near Anchorage. Based on all available monitoring data, an eruption similar to 1976 and 1986 is the most probable outcome. During January 2006, activity has been episodic, and characterized by emission of steam and ash plumes, rising to altitudes in excess of 30,000 feet, and posing hazards to aircraft in the vicinity.

This image was captured by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on Jan. 12, 2006, during an eruptive phase of Augustine. The perspective rendition shows the eruption plume derived from the ASTER image data. ASTER's stereo viewing capability was used to calculate the 3-dimensional topography of the eruption cloud as it was blown to the south by prevailing winds. From a maximum height of 9,950 feet, the plume cooled and its top descended to 6,175 feet.

The topographic relief has been increased 1.5 times for this illustration. Comparison of the ASTER plume topography data with ash dispersal models and weather radar data will allow the National Weather Service to validate and improve such models. These models are used to forecast volcanic ash plume trajectories and provide hazard alerts and warnings to aircraft in the Alaska region.

Image Credit: NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team

"Fossil Water" in LibyaIn the 1950s, oil exploration in Libya turned up another valuable resource: water. Huge aquifers, underground deposits of sand and rock that also contain water, lurked underneath the scorching sands. The Libyan government weighed the costs of bringing water up from the aquifers against transporting water from Europe and desalination of salt water, and chose the aquifers as the most cost-effective option.

The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite captured this image on April 10, 2006. This image is of Libya's massive water project, known as the Grand Omar Mukhtar, near the city of Suluq. Plans are afoot to make the Grand Omar Mukhtar the country's largest man-made reservoir. Water residing in reservoirs appears at the bottom of this image in dark blue. In this false-color image, vegetation appears red, and the brighter the red, the more robust the vegetation. In this arid place, the vegetation results from irrigated agriculture, so the areas of red appear in the crisp geometric shapes of carefully planned fields. The circular spots of red almost certainly result from center-pivot irrigation. Cityscape structures such as pavement and buildings appear in gray. Bare ground appears tan or beige.

Water hiding in aquifers can actually be cleaner than water resting in above-ground reservoirs because the process of percolating through soil and rock can remove impurities. Water can rest underground in aquifers for thousands or even millions of years. When geologic changes seal the aquifer off from further "recharging," the water inside is sometimes called "fossil water." Radiocarbon dating has revealed that some Libya's aquifer water has been there for 40,000 years, since before the end of the last ice age.

Image Credit: NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team

Stellar Rubble May Be Planetary Building BlocksThis artist's concept depicts a pulsar, which is a type of dead star, as well as the surrounding disk of rubble discovered by NASA's Spitzer Space Telescope. The pulsar, called 4U 0142+61, was once a massive star until about 100,000 years ago when it blew up in a supernova explosion and scattered dusty debris into space. Some of that debris was captured into what astronomers refer to as a "fallback disk," now circling the remaining stellar core, or pulsar. The disk resembles protoplanetary disks around young stars, out of which planets are thought to be born.

Supernovas are a source of iron, nitrogen and other "heavy metals" in the universe. They spray these elements out into space, where they eventually come together in clouds that give rise to new stars and planets. The Spitzer finding demonstrates that supernovas might also contribute heavy metals to their own planets, a possibility that was first suggested when astronomers discovered planets circling a pulsar called PSR B1257+12 in 1992.

Movie: Animation shows the death of a massive star and creation of a disk from its ashes.

Image Credit: NASA/JPL-Caltech

Quintuplet ClusterPenetrating 25,000 light-years of obscuring dust and myriad stars, the Hubble Space Telescope has provided the clearest view yet of one of the largest young clusters of stars inside our Milky Way galaxy, located less than 100 light-years from the very center of the Galaxy. Having the equivalent mass greater than 10,000 stars like our sun, the monster cluster is ten times larger than typical young star clusters scattered throughout our Milky Way. It is destined to be ripped apart in just a few million years by gravitational tidal forces in the galaxy's core. But in its brief lifetime it shines more brightly than any other star cluster in the Galaxy. The 4-million-year-old Quintuplet Cluster also is home to the brightest star seen in the galaxy, the so-called Pistol star.

Image Credit: NASA

Happy Sweet Sixteen, Hubble!This mosaic image from the Hubble and Spitzer telescopes and the Chandra Observatory is the sharpest wide-angle view ever obtained of of the magnificent starburst galaxy, Messier 82 (M82). The galaxy is remarkable for its bright blue disk, webs of shredded clouds, and fiery-looking plumes of glowing hydrogen blasting out of its central regions. The Hubble Space Telescope was launched on April 24, 1990, aboard the shuttle Discovery. Over its 16-year history, Hubble has taken many hundreds of images that have expanded our knowledge of the universe. Throughout the galaxy's center, young stars are being born 10 times faster than they are inside our entire Milky Way Galaxy. The resulting huge concentration of young stars carved into the gas and dust at the galaxy's center and the fierce galactic superwind generated from these stars compresses enough gas to make millions of more stars. In M82, young stars are crammed into tiny but massive star clusters. These, in turn, congregate together by the dozens to make the bright patches, or "starburst clumps," in the central parts of the galaxy. The rapid rate of star formation in this galaxy eventually will be self-limiting, because as star formation becomes too vigorous, it will consume or destroy the material needed to make more stars. The starburst then will subside, probably in a few tens of millions of years. Located 12 million light-years away, M82 appears high in the northern spring sky in the direction of the constellation Ursa Major, the Great Bear. It is also called the "Cigar Galaxy" because of the elliptical shape produced by the oblique tilt of its starry disk relative to our line of sight. Image Credit: NASA, ESA, and The Hubble Heritage Team (STScI)

Alaska's Malaspina GlacierThe tongue of the Malaspina Glacier, the largest glacier in Alaska, fills most of this image. The Malaspina lies west of Yakutat Bay and covers 1,500 square miles (3,880 square kilometers).

This is a false-color composite image made using infrared, near infrared, and green wavelengths. The image has also been sharpened using the sensor's panchromatic band. The image was acquired by Landsat 7's Enhanced Thematic Mapper plus (ETM+) sensor on August 31, 2000.

Image Credit: NASA/USGS

Neptune on Triton's HorizonThis composite illustration is of the planet Neptune, as seen from its moon Triton. Neptune's south pole is to the left; clearly visible in the planets' southern hemisphere is a Great Dark Spot, a large anti-cyclonic storm system. This three-dimensional view was created using images from the Voyager spacecraft. Image Credit: NASA

1906 San Francisco EarthquakeAlong the coast of California, the tectonic plate underlying the Pacific Ocean and the plate harboring the North American landmass meet at the San Andreas Fault. Intense pressure builds up along the fault as the two plates grind past each other. On the morning of April 18, 1906, the pent-up pressure was released in a major earthquake that thundered across coastal California. The earthquake ruptured the ground for 296 miles (477 kilometers) along the northernmost section of the San Andreas Fault, and the ground surfaces on either side of the rupture slipped more than 20 feet away from each other in some places. The quake set off a catastrophic fire in San Francisco that devastated the city.

This image shows the topography of the region using data from NASA's Shuttle Radar Topography Mission. Low elevations are green, with yellow, pink, and white representing progressively higher elevations. Major geologic faults are marked with white lines. The San Andreas Fault runs in a northwest-southeast line along the coast. The numbers on the fault line indicate how far the ground surface slipped at that location as a result of the 1906 earthquake. Also labeled in the image is the Hayward Fault on the eastern side of San Francisco Bay. The Hayward is one of the faults with a high likelihood of a major earthquake in coming decades. That fault runs through Oakland and Berkeley. Image Credit: NASA

Oresund BridgeIn 1991, the governments of Denmark and Sweden agreed to build a bridge to connect the two countries across the Oresund Strait. The 16-kilometer-long Oresund Link between Malmo, Sweden (right), and Copenhagen, Denmark (left), was completed and opened to traffic in 2000. Denmark and Sweden were linked once more —7,000 years after rising sea levels accompanying the end of the Ice Age severed the dry-land connection between the two. The Oresund Link has three main segments. On the Denmark side, the link begins with a 3,510-meter (2.2-mile) underwater tunnel. The tunnel emerges from the water onto a roadway on a 4,055-meter (2.5-mile) artificial island, Peberholm, which appears as a bright white shape to the south of the natural island in the scene. The cable-supported Oresund Bridge stretches 7,845 meters (4.9 miles) across the eastern part of the Strait toward Sweden, making a thin white line across the image. Deep water appears dark blue, shallow water appears bright blue, vegetation appears green, and developed or paved areas appear white. Several white specks in the waters of the Strait are boats or ships. Image Credit: NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team

Spirit Studies Rock Outcrop at 'Home Plate'Mars Exploration Rover Spirit acquired this false-color image on the rover's on Martian day, or sol, 746 (Feb. 26, 2006) after using the rock abrasion tool to brush the surfaces of rock targets informally named "Stars" (left) and "Crawfords" (right). Small streaks of dust extend for several centimeters behind the small rock chips and pebbles in the dusty, red soils.

The targets Stars and Crawfords are on a rock outcrop located on top of "Home Plate." The outcrop is informally named "James 'Cool Papa' Bell," after a Negro Leagues Hall of Famer who played for both the Pittsburgh Crawfords and the Kansas City Stars. To some science team members, the two brushed spots resemble the eyes of a face, with rocks below and between the eyes as a nose and layered rocks at the bottom of the image as a mouth.

The image combines frames taken by Spirit's panoramic camera through the camera's 753-nanometer, 535-namometer, and 432-nanometer filters. It is enhanced to emphasize color differences among the rocks, soils and brushed areas. The blue circular area on the left, Stars, was brushed on 761 (Feb. 22, 2006). The one on the right, Crawfords, was brushed on sol 763 (Feb. 25, 2006).

Image Credit: NASA/JPL-Caltech/USGS/Cornell

Smokin' Hot GalaxyThis infrared image from NASA's Spitzer Space Telescope shows a galaxy that appears to be sizzling hot, with huge plumes of smoke swirling around it. The galaxy, known as Messier 82 or the "Cigar galaxy," is in fact, smothered in smoky dust particles (red) blown out into space by the galaxy's hot stars (blue).

It took all three of Spitzer's instruments to show that the galaxy is also surrounded by a huge, hidden halo of smoky dust that appears red in infrared image. Of those instruments, Spitzer's infrared spectrograph told astronomers that the dust contains a carbon-containing compound, called polycyclic aromatic hydrocarbon. This smoky molecule can be found on Earth in tailpipes, barbecue pits and other places where combustion reactions have occurred.

Image Credit: NASA/JPL-Caltech/University of Arizona

Bogda MountainsThe Turpan Depression, nestled at the foot of China’s Bogda Mountains, is a strange mix of salt lakes and sand dunes. It is one of the few landscapes in the world that lies below sea level.

This image was acquired by Landsat 7’s Enhanced Thematic Mapper plus (ETM+) sensor.

Image Credit: NASA/USGS

Death Becomes HerThis stunning false-color picture shows off the many sides of the supernova remnant Cassiopeia A, which is made up of images taken by three of NASA's Great Observatories, using three different wavebands of light. Infrared data from the Spitzer Space Telescope are colored red; visible data from the Hubble Space Telescope are yellow; and X-ray data from the Chandra X-ray Observatory are green and blue.

Located 10,000 light-years away in the northern constellation Cassiopeia, Cassiopeia A is the remnant of a once massive star that died in a violent supernova explosion 325 years ago. It consists of a dead star, called a neutron star, and a surrounding shell of material that was blasted off as the star died. The neutron star can be seen in the Chandra data as a sharp turquoise dot in the center of the shimmering shell.

+ Read More: http://www.nasa.gov/vision/universe/starsgalaxies/spitzer-060905.html

Image Credit: NASA/JPL-Caltech/STScI/CXC/SAO

Galactic Dust BunniesThe yearly ritual of spring cleaning clears a house of dust as well as dust "bunnies," those pesky balls that frolic under beds and behind furniture. NASA's Hubble Space Telescope has photographed similar dense knots of dust and gas in our Milky Way Galaxy, but this dust isn't a nuisance. It's a concentration of elements responsible for the formation of stars throughout the universe.

These opaque, dark knots of gas and dust are called "Bok globules," named after astronomer Bart Bok, who proposed their existence in the 1940's. They're absorbing light in the center of the nearby star-forming region known as NGC 281, ocated nearly 9,500 light-years away in the direction of the constellation Cassiopeia.

Bok hypothesized that giant molecular clouds, on the order of hundreds of light-years in size, can become perturbed and form small pockets where the dust and gas are highly concentrated. These small pockets become gravitationally bound and accumulate dust and gas from the surrounding area. If they can capture enough mass, they have the potential of creating stars in their cores; however, not all Bok globules will form stars. Some will dissipate before they can collapse to form stars. That may be what's happening to the globules seen here.

Image Credit: NASA, ESA, and The Hubble Heritage Team (STScI/AURA)

Viewing EarthThis computer generated image depicts a view of Earth as seen from the surface of the asteroid Toutatis on Nov. 29, 1996. Toutatis currently approaches Earth once every four years, and on Nov. 29th, 1996 was 5.2 million kilometers (3.3 million miles) away.

Image Credit: NASA

Tibetan BraidThis view of Tibet’s Brahmaputra River was taken on Oct. 13, 2000, by the Expedition 3 crew. This Asian river carves a narrow west-east valley between the Tibetan Plateau to the north and the Himalaya Mountains to the south, as it rushes eastward for more than 1,500 km in southwestern China. This area pictured is a 15-km stretch south of the ancient Tibetan capital of Lhasa where the river flow becomes intricately braided as it works and reworks its way through extensive deposits of erosional material.

Image Credit: NASA/JPL/Space Science Institute

Stephan’s QuintetThis false-color composite image of the Stephan’s Quintet galaxy cluster clearly shows one of the largest shock waves ever seen (green arc). The wave was produced by one galaxy falling toward another at speeds of more than one million miles per hour. The image is made up of data from NASA's Spitzer Space Telescope and a ground-based telescope in Spain.

Four of the five galaxies in this picture are involved in a violent collision, which has already stripped most of the hydrogen gas from the interiors of the galaxies. The centers of the galaxies appear as bright yellow-pink knots inside a blue haze of stars, and the galaxy producing all the turmoil, NGC7318b, is the left of two small bright regions in the middle right of the image. One galaxy, the large spiral at the bottom left of the image, is a foreground object and is not associated with the cluster.

The titanic shock wave, larger than our own Milky Way galaxy, was detected by the ground-based telescope using visible-light wavelengths. It consists of hot hydrogen gas. As NGC7318b collides with gas spread throughout the cluster, atoms of hydrogen are heated in the shock wave, producing the green glow.

Stephan's Quintet is located 300 million light-years away in the Pegasus constellation.

For more information, visit the Planetary Photojournal

Image credit: NASA/JPL-Caltech/Max Planck Institute

SuitSat-1 Floats FreeA space suit floats freely away from the International Space Station in a scene reminiscent of a sci-fi movie. But this time, no investigation is needed. The suit is actually the world's latest satellite and was launched on Feb. 3, 2006. Dubbed SuitSat-1, the unneeded Russian Orlan spacesuit filled mostly with old clothes was fitted with a radio transmitter and released to orbit the Earth.

Image Credit: NASA

Galactic Hearts of GlassThis artist's concept shows delicate green crystals sprinkled throughout the core of a pair of colliding galaxies. The white spots represent a thriving population of stars of all sizes and ages. NASA's Spitzer Space Telescope detected more than 20 bright and dusty galactic mergers like the one depicted here, all teeming with the tiny gem-like crystals.

When galaxies collide, they trigger the birth of large numbers of massive stars. Astronomers believe these blazing hot stars act like furnaces to produce silicate crystals in the same way that glass is made from sand. The stars probably shed the crystals as they age, and as they blow apart in supernovae explosions.

Image Credit: NASA/JPL-Caltech

NGC 281: Cluster, Clouds, and GlobulesNGC 281 is a busy workshop of star formation. Prominent features include a small open cluster of stars, a diffuse red-glowing emission nebula, large lanes of obscuring gas and dust, and dense knots of dust and gas in which stars may still be forming. The open cluster of stars IC 1590 visible around the center has formed only in the last few million years. The brightest member of this cluster is actually a multiple-star system shining light that helps ionize the nebula's gas, causing the red glow visible throughout. The lanes of dust visible below the center are likely homes of future star formation. Particularly striking in the above photograph are the dark Bok globules visible against the bright nebula. Stars are surely forming there right now. The entire NGC 281 system lies about 10 thousand light years distant.

Credit & Copyright: Jean-Charles Cuillandre (CFHT), Hawaiian Starlight, CFHT

The Andromeda GalaxyAndromeda is the nearest major galaxy to our own Milky Way Galaxy. Our Galaxy is thought to look much like Andromeda. Together these two galaxies dominate the Local Group of galaxies. The diffuse light from Andromeda is caused by the hundreds of billions of stars that compose it. The several distinct stars that surround Andromeda's image are actually stars in our Galaxy that are well in front of the background object. Andromeda is frequently referred to as M31 since it is the 31st object on Messier's list of diffuse sky objects. M31 is so distant it takes about two million years for light to reach us from there. Much about M31 remains unknown, including why the center contains two nuclei.

The Andromeda Galaxy

Our SunExtreme Ultraviolet Imaging Telescope (EIT) image of a huge, handle-shaped prominence taken on Sept. 14,1999 taken in the 304 angstrom wavelength - Prominences are huge clouds of relatively cool dense plasmasuspended in the Sun's hot, thin corona. At times, they can erupt,escaping the Sun's atmosphere. Emission in this spectral line shows theupper chromosphere at a temperature of about 60,000 degrees K. Everyfeature in the image traces magnetic field structure. The hottest areasappear almost white, while the darker red areas indicate coolertemperatures. Courtesy of SOHO/Extreme Ultraviolet Imaging Telescope (EIT) consortium. SOHO is a project of international cooperation between ESA and NASA.

Our Sun