Arkhangelsk, Russia

Arkhangelsk (or Archangel in English) is a city and the administrative capital of Archangelsk Oblast, Russia. It is situated on both banks of the Dvina River near where it flows into the White Sea. As early as 800 the area was known to the Vikings to have a settlement, that they raided around 1000. In the 12th century, the Novogordians established the Archangel Michael Monastery. For the next 400 years, conflict between Russia and Sweden for control of the White Sea and the Kola Peninsula led to shifting rulers for Arkhangelsk. Construction of a railway to Moscow in the late 1800s signaled a revival of the city's economy. During both world wars, Arkhangelsk was a major port of entry for Allied aid. The image was acquired July 14, 2010, covers an area of 37.3 x 53.1 km, and is located at 64.5 degrees north latitude, 40.5 degrees east longitude.

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

Enceladus and Saturn's Rings

The Cassini spacecraft looks over cratered and tectonically deformed terrain on Saturn's moon Enceladus as the camera also catches a glimpse of the planet's rings in the background. The image was captured during the spacecraft's flyby of Enceladus on November 30, 2010.

Geologically young terrain in the middle latitudes of the moon gives way to older, cratered terrain in the northern latitudes. See PIA11685 to learn more. This view is centered on terrain at 41 degrees north latitude, 202 degrees west longitude. North on Enceladus (504 kilometers, or 313 miles, across) is up and rotated 28 degrees to the right.

This view looks toward the northern, sunlit side of the rings from less than a degree above the ringplane.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera. The view was acquired at a distance of approximately 46,000 kilometers (29,000 miles) from Enceladus and at a Sun-Enceladus-spacecraft, or phase, angle of 14 degrees. Image scale is 276 meters (906 feet) per pixel.

Photo credit: NASA/JPL/Space Science Institute

Zeta Ophiuchi Bow Shock

The blue star near the center of this image is Zeta Ophiuchi. When seen in visible light it appears as a relatively dim red star surrounded by other dim stars and no dust. However, in this infrared image taken with NASA's Wide-field Infrared Survey Explorer, or WISE, a completely different view emerges. Zeta Ophiuchi is actually a very massive, hot, bright blue star plowing its way through a large cloud of interstellar dust and gas.

Astronomers theorize that this stellar juggernaut was likely once part of a binary star system with an even more massive partner. It's believed that when the partner exploded as a supernova, blasting away most of its mass, Zeta Ophiuchi was suddenly freed from its partner's pull and shot away like a bullet moving 24 kilometers per second (54,000 miles per hour). Zeta Ophiuchi is about 20 times more massive and 65,000 times more luminous than the sun. If it weren't surrounded by so much dust, it would be one of the brightest stars in the sky and appear blue to the eye. Like all stars with this kind of extreme mass and power, it subscribes to the 'live fast, die young' motto. It's already about halfway through its very short 8-million-year lifespan. In comparison, the sun is roughly halfway through its 10-billion-year lifespan. While the sun will eventually become a quiet white dwarf, Zeta Ophiuchi, like its ex-partner, will ultimately die in a massive explosion called a supernova.

Perhaps the most interesting features in this image are related to the interstellar gas and dust that surrounds Zeta Ophiuchi. Off to the sides of the image and in the background are relatively calm clouds of dust, appearing green and wispy, slightly reminiscent of the northern lights. Near Zeta Ophiuchi, these clouds look quite different. The cloud in all directions around the star is brighter and redder, because the extreme amounts of ultraviolet radiation emitted by the star are heating the cloud, causing it to glow more brightly in the infrared than usual.

Even more striking, however, is the bright yellow curved feature directly above Zeta Ophiuchi. This is a magnificent example of a bow shock. In this image, the runaway star is flying from the lower right towards the upper left. As it does so, its very powerful stellar wind is pushing the gas and dust out of its way (the stellar wind extends far beyond the visible portion of the star, creating an invisible 'bubble' all around it). And directly in front of the star's path the wind is compressing the gas together so much that it is glowing extremely brightly (in the infrared), creating a bow shock. It is akin to the effect you might see when a boat pushes a wave in front it as it moves through the water. This feature is completely hidden in visible light. Infrared images like this one from WISE shed an entirely new light on the region.

The colors used in this image represent specific wavelengths of infrared light. Blue and cyan (blue-green) represent light emitted at wavelengths of 3.4 and 4.6 microns, which is predominantly from stars. Green and red represent light from 12 and 22 microns, respectively, which is mostly emitted by dust.

Photo credit: NASA/JPL-Caltech/UCLA

Mercury in Color

During MESSENGER's second flyby of Mercury, MDIS acquired a strip of high-resolution images obtained with each of the WAC's 11 different color filters. The graphic shown here displays the resulting enhanced-color mosaic and gives considerable detail about the images, how the mosaic was created, and the geologic features that can be seen.

Currently, these images are the highest-resolution color images ever obtained of the Solar System's innermost planet, but not for long! On March 18, 2011, MESSENGER will enter into orbit about Mercury, and the mission's extensive, year-long science observation campaign will begin. That campaign includes capturing color images of Mercury's surface at higher resolution than ever before.

Special thanks to Kathryn Powell, a summer intern student with the MESSENGER project, for contributing to the content of this graphic. Note: since the original creation of this graphic, the crater identified in the upper right with the label "young rayed crater" has been named Dominici. See PIA12871 to learn more about this recently named crater.

Date Acquired: October 6, 2008
Instrument: Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS)

Photo credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

Note: There is a very nice annotated poster of this image located here.

Messier 1: The Crab Nebula

This is a composite image of the Crab Nebula, probably the most iconic relic of a star's demise: first spotted as a supernova in 1054 AD, this object appears today as the remnant of that explosion, a vast nebula hosting a rapidly spinning neutron star, or pulsar, at its core.

The optical view of the nebula, obtained by the NASA/ESA Hubble Space Telescope, is shown in red and yellow, the X-ray image obtained by the Chandra X-ray Observatory is shown in blue, and the Spitzer Space Telescope's infrared image is in purple. At infrared and optical wavelengths the intricate structure of the nebula is visible on a larger scale, whereas the X-ray image shows the emission coming from the most highly energetic electrons, which are concentrated much closer to the central pulsar powering the entire nebula's emission.

The image is 5 arc-minutes across.

Photo credit: X-ray: NASA/CXC/SAO/F. Seward; Optical: NASA/ESA/ASU/J. Hester & A. Loll; Infrared: NASA/JPL-Caltech/Univ. Minn./R. Gehrz

Note: For more information, see The Crab Nebula: Standard Candle No More?.

Maffei 2 - The Hidden Galaxy

Maffei 2 is the poster child for an infrared galaxy that is almost invisible to optical telescopes. Foreground dust clouds in our Milky Way galaxy block about 99.5 percent of its visible light. But this infrared image from NASA's Spitzer Space Telescope penetrates the dust to reveal the galaxy in all its glory.

The astronomer Paolo Maffei first noted the galaxy as a mysterious smudge on an infrared photographic plate in 1968. Four years later, he identified the strange object to be a galaxy, now named after him. This discovery was made in the infancy of infrared astronomy, and it would take many technological innovations in the following decades to allow astronomers to study obscured objects like this one in detail.

Most other galaxies the size of Maffei 2 had been cataloged for over a century. Because this galaxy was hidden behind dust lanes in our own galaxy, it did not become one of the entries in the famous 18th century catalog of bright deep-sky objects compiled by Charles Messier.

This Spitzer image clearly shows the unusual structure of Maffei 2. The strong central bar and asymmetric spiral arms help identify why the galaxy also harbors a "starburst" in its very core. Such dramatic bursts of star formation occur when massive amounts of dust and gas are driven into the center of a galaxy, often by gravitational interactions that create the barred spiral structures.

Photo credit: NASA/JPL-Caltech/UCLA

Note: This is MinSEx's 300th post!

Delta Cephei - Standard Candle in the Wind

This image layout illustrates how NASA's Spitzer Space Telescope was able to show that a "standard candle" used to measure cosmological distances is shrinking -- a finding that affects precise measurements of the age, size and expansion rate of our universe. The image on the left, taken by Spitzer in infrared light, shows Delta Cephei, a type of standard candle used to measure the distances to galaxies that are relatively close to us. Cepheids like this one are the first rungs on the so-called cosmological distance ladder -- a tool needed to measure farther and farther distances.

Spitzer showed that the star has a bow shock in front of it. This can be seen as the red arc shape to the left of the star, which is depicted in blue-green (the colors have been assigned to specific infrared wavelengths we can't see with our eyes). The presence of the bow shock told astronomers that Delta Cephei must have a wind that is forming the shock. This wind is made up of gas and dust blowing off the star. Before this finding, there was no direct proof that Cepheid stars could lose mass, or shrink.

The finding is important because the loss of mass around a Cepheid can obscure the star's light, making it appear brighter in infrared observations, and dimmer in visible light, than it really is. This, in turn, affects calculations of how far away the star is. Even tiny inaccuracies in such distant measurements can cause the whole cosmological distance ladder to come unhinged.

The diagram on the right in Figure 1 illustrates how Delta Cephei's bow shock was formed. As the star speeds along through space, its wind hits interstellar gas and dust, causing it to pile up in the bow shock. A companion star to Delta Cephei, seen just below it, is lighting up the region, allowing Spitzer to better see the region. By examining the structure of the bow shock, astronomers were able to calculate how fast the star is losing mass.

In this image, infrared light captured by the infrared array camera is blue and blue-green (3.6- and 4.5-micron light is blue and 8.0-micron light is blue-green). Infrared light captured by the multiband imaging photometer is colored green and red (24-micron light is green and 70-micron light is red).

Photo credit: NASA/JPL-Caltech/Iowa State

Cold Cores in the Milky Way

This map illustrates the numerous star-forming clouds, called cold cores, that Planck observed throughout our Milky Way galaxy. Planck, a European Space Agency mission with significant NASA participation, detected around 10,000 of these cores, thousands of which had never been seen before. Cold cores are chilly chambers of gas and dust where stellar embryos are just beginning to take shape. Some of the cold cores found by Planck are the coldest ever observed, as cold as just seven degrees above absolute zero, or minus 447 degrees Fahrenheit.

The blue data show the density of the cores, some of which are shaped more like clumps or filaments than spherical cores. Other missions, like the Herschel Space Observatory, can follow-up on the Planck discoveries, and see the structures in more detail.

Planck is an all-sky survey mission, scanning the sky at longer wavelengths of light, ranging from infrared to radio waves. Its ultimate goal is to measure the cosmic microwave background -- ancient radiation from the Big Bang that created our universe 13.7 billion years ago. But in the process of making these precise measurements, Planck is catching objects that lie in front of the cosmic microwave background -- objects like cold cores in our galaxy, in addition to distant galaxies.

About 1,000 of the cold cores observed by Planck are being released to the public January 11, 2011, in the mission's "Early Release Compact Source Catalogue." These are the best sources of the bunch, and the coldest.

Photo credit: ESA/NASA/JPL-Caltech

COSMOS-AzTEC3 Proto-Galactic Cluster

Astronomers have discovered a massive cluster of young galaxies forming in the distant universe. The growing galactic metropolis, named COSMOS-AzTEC3, is the most distant known massive "proto-cluster" of galaxies, lying about 12.6 billion light-years away from Earth. Members of the developing cluster are shown here, circled in white, in this image taken by Japan's Subaru telescope atop Mauna Kea in Hawaii. The cluster was discovered by a suite of multi-wavelength telescopes, including NASA's Spitzer, Chandra and Hubble space observatories, Subaru and the W.M. Keck Observatory, also atop Mauna Kea in Hawaii.

The other dots in this picture are stars or galaxies that are not members of the cluster -- most of the them are located closer to us than the cluster, but some are farther away. The two brightest spots are stars. Though they appear bright in this image, they are actually tens of thousands of times fainter than what we can see with our eyes.

Photo credit: Subaru/NASA/JPL-Caltech

Messier 81 and 82

This image from NASA's Wide-Field Infrared Survey Explorer, or WISE, features two stunning galaxies engaged in an intergalactic dance. The galaxies, Messier 81 and Messier 82, swept by each other a few hundred million years ago, and will likely continue to twirl around each other multiple times before eventually merging into a single galaxy. The relatively recent encounter triggered a spectacular burst of star formation visible in both galaxies.

Messier 81 (bottom of image) is a prototypical "grand design" spiral galaxy with its pronounced and well-defined arms spiraling into its core. At the wavelengths WISE sees, these beautiful arms show areas of compressed interstellar gas and dust, which go hand-in-hand with areas of increased star formation. The spiral density waves that create this compression and star formation have been enhanced by the close gravitational interaction with its partner galaxy, Messier 82, causing the arms to appear more prominent than what is typically seen in other isolated spiral galaxies.

Messier 82 (top of image) is also a spiral galaxy. However, it is seen edge-on from our point of view. It was originally classified as an irregular galaxy, until 2005, when astronomers were able to tease out spiral structure in near-infrared images (similar to wavelengths that WISE sees). Viewed in visible wavelengths, this galaxy appears to have a long thin bar shape, hence its common name, the Cigar Galaxy.

Messier 82 is also a starburst galaxy, meaning it is currently forming stars at an exceptionally high rate. This huge burst of activity was caused by its close encounter with Messier 81, whose gravitational influence caused gas near the center of Messier 82 to rapidly compress. This compression triggered an explosion of star formation, concentrated near the core. The intense radiation from all of the newly formed massive stars creates a galactic "superwind" that is blowing massive amounts of gas and dust out perpendicular to the plane of the galaxy. This ejected material (seen as the orange/yellow areas extending up and down) is made mostly of polycyclic aromatic hydrocarbons, which are common products of combustion here on Earth. It can literally be thought of as the smoke from the cigar.

A third, smaller galaxy, NGC 3077, can be seen at lower left. This spiral galaxy belongs to the same group as Messier 81 and Messier 82 -- a group that includes at least a dozen gravitationally linked galaxies. NGC 3077 is also experiencing a burst of new star birth, likely triggered by its interaction with Messier 81.

Messier 81 and Messier 82 are both very bright galaxies and can be seen on a clear, dark night with binoculars in the northern constellation Ursa Major, which contains the Big Dipper. In visible light, Messier 81 is one of the brightest galaxies that can be seen. Messier 82 is not as bright at visible wavelengths, but in infrared light, it is by far the brightest galaxy in the entire night sky.

This image was made from observations by all four infrared detectors aboard WISE. Blue and cyan (blue-green) represent infrared light at wavelengths of 3.4 and 4.6 microns, which is primarily light from stars. Green and red represent light at 12 and 22 microns, which is primarily emission from warm dust.

Photo credit: NASA/JPL-Caltech/UCLA

Solar Wind Shaping Magnetospheres of Earth and Venus

Artist's impression showing how the solar wind shapes the magnetospheres of Venus (shown with a brown tail, closer to the Sun) and Earth (shown in blue). Both planets are roughly the same size. Venus is closer to the Sun, at roughly 0.7 AU (Astronomical Unit) while Earth is located at 1 AU. Unlike Venus, Earth has an internal magnetic field which makes its magnetosphere bigger. The lines coming out of the Sun symbolize the propagation direction of the solar wind.

Image credit: ESA

Note: For more information, see ESA Spacecraft Model Magnetic Boundaries.

Messier 8 - The Lagoon Nebula

This colorful picture is a mosaic of the Lagoon Nebula taken by NASA's Wide-field Infrared Survey Explorer, or WISE. Normally, you would expect a lagoon to be filled with water, but this nebula is composed of clouds of gas and dust in which new stars are forming. Also known as Messier 8, or simply M8, the Lagoon Nebula is seen here as a large circular cloud in the center of the image, surrounded by innumerable stars.

This view is looking toward the center of the Milky Way, which is our home galaxy. Our solar system is located on one of the spiral arms, about halfway out from the center of the disk-shaped Milky Way galaxy. When we view the Milky Way from Earth, we are looking into the disk of the galaxy where stars are so numerous that they appear to us as a cloudy band of light stretching across the sky. The center of the Milky Way is located in the constellation Sagittarius, which is where the Lagoon Nebula can be found. M8 is a favorite target for amateur astronomers because it can be easily seen with binoculars or a small telescope.

Astronomers have identified several different parts of the Lagoon Nebula, including M8E, a young stellar object, and the star clusters NGC 6523 and NGC 6530 (sometimes the designation of NGC 6523 is used interchangeably with M8). At the center of the Lagoon Nebula is the star Herschel 36. Distance measurements to this nebula vary widely, from 4,000 to 6,500 light-years away from Earth. Also included in this image but not classified as part of M8, is another cloud of warm dust and gas, located up and to the right of M8. This cloud is emitting infrared radiation.

All four of WISE's infrared detectors were used to take this image. The colors used represent specific wavelengths of infrared radiation. Blue and blue-green (cyan) represent 3.4- and 4.6-micron light, respectively. These wavelengths are mainly emitted by hot stars within the Milky Way. Green represents 12-micron light, which is emitted by the warm gas of the nebulae. Red represents the longest-wavelength, 22-micron light emitted by cooler dust within the nebulae.

Photo credit: NASA/JPL-Caltech/UCLA

The Andromeda Galaxy in Infrared and X-Rays

This mosaic of the Andromeda spiral galaxy highlights explosive stars in its interior, and cooler, dusty stars forming in its many rings. The image is a combination of observations from the Herschel Space Observatory taken in infrared light (seen in orange hues), and the XMM-Newton telescope captured in X-rays (seen in blues). NASA plays a role in both of these European Space Agency-led missions.

Herschel provides a detailed look at the cool clouds of star birth that line the galaxy's five concentric rings. Massive young stars are heating blankets of dust that surround them, causing them to glow in the longer-wavelength infrared light, known as far-infrared, that Herschel sees.

In contrast, XMM-Newton is capturing what happens at the end of the lives of massive stars. It shows the high-energy X-rays that come from, among other objects, supernova explosions and massive dead stars rotating around companions. These X-ray sources are clustered in the center of the galaxy, where the most massive stars tend to form.

Andromeda is our Milky Way galaxy's nearest large neighbor. It is located about 2.5 million light-years away and holds up to an estimated trillion stars. Our Milky Way is thought to contain about 200 billion to 400 billion stars.

Photo credit: European Space Agency

Note: For more information, see Andromeda’s Once and Future Stars

Mercury Landscape

When MESSENGER first flew by Mercury on January 14, 2008, MDIS acquired images of a large portion of Mercury's surface that had never previously been seen by spacecraft. This mosaic of NAC images shows some of the geologic features discovered during that first flyby that have been subsequently named: the curving cliff face of Beagle Rupes, the elongated crater Sveinsdottir, and the craters Izquierdo and Kunisada flooded with lava.

This year, the MESSENGER spacecraft is positioned once again to visit the Solar System's innermost planet. However, this time, the spacecraft won't just pass by. On March 18, 2011, a 15-minute maneuver will place MESSENGER in orbit about Mercury, making it the first spacecraft ever to do so. The MESSENGER mission will then begin an extensive year-long science campaign to unravel Mercury's mysteries. 2011 promises to be an exciting year of further discoveries for the MESSENGER mission.

Date Acquired: January 14, 2008
Instrument: Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
Scale: Izquierdo Crater is 170 kilometers (106 miles) in diameter.

Photo credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

Messier 33 - The Triangulum Galaxy

This image captured by NASA's Wide-field Infrared Survey Explorer, or WISE, shows of one of our closest neighboring galaxies, Messier 33. Also named the Triangulum galaxy (after the constellation it's found in), M33 is one of largest members in our small neighborhood of galaxies -- the Local Group. The Local Group consists of about 30 galaxies that are gravitationally bound and travel together through the universe. M33 is the third largest member of the Local Group, dwarfed only by the Andromeda galaxy (M31) and our very own home galaxy, the Milky Way.

M33 is extremely close as far as galaxies go, residing only 3 million light-years away. Its proximity, along with it being conveniently tilted towards Earth (about 54 degrees to the line of sight), make it very easy for astronomers to study in detail. The infrared images that WISE produces contribute to astronomers' overall understanding of a variety of processes happening in the galaxy. Areas in the spiral arms that are hidden behind dust in visible light shine through brightly in infrared light, showing where clouds of cool gas are concentrated. Star-forming regions are easy to spot in infrared (green and red areas in this image). Notice that there isn't a lot of star formation occurring near the center of M33. It would be difficult to deduce this lack of activity in the core by only looking a visible-light image, where the core appears to be the brightest feature. This infrared image also shows that the galaxy is surprisingly bigger than it appears in visible light. The cold dust seen by WISE extends much further out from the core than anticipated.

The bright yellow-orange 'blobs' scattered throughout M33 are areas where stars are forming at an especially intense rate. The largest one in the spiral arm to the upper left has its own name, NGC 604. It's an "H II" region -- an area of gas that is being heated and ionized by powerful young stars recently born inside of it. The Orion nebula is an example of a nearby H II region within our own Milky Way galaxy. NGC 604, however, is the largest such region in the entire Local Group of galaxies. It is over 40 times larger than the Orion nebula and much brighter. If NGC 604 were at the same distance from Earth as the Orion nebula, it would be the brightest object in the night sky (besides the Moon).

M33 is over 50,000 light years across (about half the size of the Milky Way). Because it is so close it appears quite large to us, covering a piece of sky nearly four times bigger than the full moon. Its relatively low surface brightness makes it difficult for human eyes to see, however. Even so, under exceptionally dark skies it can be seen with the unaided eye, making it one of the farthest objects visible without a telescope.

These images were made from observations by all four infrared detectors aboard WISE. Blue and cyan, or blue-green, represent infrared light at wavelengths of 3.4 and 4.6 microns, which is primarily light from stars. Green and red represent light at 12 and 22 microns, which is primarily light emitted from warm dust.

Photo credit: NASA/JPL-Caltech/UCLA

He2-90

Astronomers using NASA's Hubble Space Telescope have stumbled upon a mysterious object that is grudgingly yielding clues to its identity. A quick glance at the Hubble picture at top shows that this celestial body, called He2-90, looks like a young, dust-enshrouded star with narrow jets of material streaming from each side. But it's not. The object is classified as a planetary nebula, the glowing remains of a dying, lightweight star. But the Hubble observations suggest that it may not fit that classification, either. The Hubble astronomers now suspect that this enigmatic object may actually be a pair of aging stars masquerading as a single youngster. One member of the duo is a bloated red giant star shedding matter from its outer layers. This matter is then gravitationally captured in a rotating, pancake-shaped accretion disk around a compact partner, which is most likely a young white dwarf (the collapsed remnant of a Sun-like star). The stars cannot be seen in the Hubble images because a lane of dust obscures them.

Photo credit: NASA, Raghvendra Sahai (NASA Jet Propulsion Laboratory, Lars-Ake Nyman (European Southern Observatory Chile & Onsala Space Observatory, Sweden

Flight over Triton

This simulated voyage over the surface of Neptune's large moon Triton was produced using topographic maps derived from images acquired by NASA's Voyager spacecraft during its August 1989 flyby, 20 years ago.

Triton was the last solid object visited by the Voyager 2 spacecraft on its epic 10-year tour of the outer solar system. Voyager mapped only the hemisphere that faces Neptune, but revealed a very young surface scarred by rising blobs of ice (diapirs), faults, and volcanic pits and lava flows composed of water and other ices. The video begins near the western edge of this hemisphere with an approach over cantaloupe terrain and two large smooth walled plains. The video tracks due east for roughly 1500 kilometers over a large province of volcanic pits, calderas and smooth plains. As can be seen in this video, Triton is locally very rugged (with pits and mounds that are typically a few hundred meters [several hundred feet] high), but has no large mountains or deep basins and regional relief is low. The lack of large topographic features is a consequence of Triton's high internal heat and the low strength of most ices.

The video was produced by using a new topographic map of Triton, combined with a 1.65-kilometer resolution image mosaic. Topographic mapping was based on shape-from-shading analysis of the original Voyager images. Vertical relief has been exaggerated by a factor of 25 to aid interpretation.

Video credit: NASA/JPL/Universities Space Research Association/Lunar & Planetary Institute

False Color View of Enceladus and Saturn's E-Ring

The ice jets of Enceladus send particles streaming into space hundreds of kilometers above the south pole of this spectacularly active moon. Some of the particles escape to form the diffuse E ring around Saturn. This color-coded image was processed to enhance faint signals, making the contours and extent of the fainter, larger-scale component of the plume easier to see.

The bright strip behind and above Enceladus (505 kilometers) is the E ring, in which this intriguing body resides. The small round object at far left is a background star.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on 24 March 2006 at a distance of approximately 1.9 million kilometers from Enceladus and at a Sun-Enceladus-spacecraft, or phase, angle of 162 degrees. Image scale is 11 kilometers per pixel.

Photo credit: NASA/JPL/Space Science Institute

Earth and Moon by Voyager 1

This picture of a crescent-shaped Earth and Moon -- the first of its kind ever taken by a spacecraft -- was recorded September 18, 1977, by NASA's 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 Jet Propulsion Laboratory's Image Processing Lab. 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 print. Voyager 2 was launched August 20, 1977, followed by Voyager 1 on September 5, 1977, en route to encounters at Jupiter in 1979 and Saturn in 1980 and 1981.

Photo credit: NASA/JPL