Sunspots and Solar Flares

NASA's Solar Dynamics Observatory (SDO) captured this image of an M7.9 class flare on March 13, 2012 at 1:29 p.m. EDT. It is shown here in the 131 Angstrom wavelength, a wavelength particularly good for seeing solar flares and a wavelength that is typically colorized in teal. The flare peaked at 1:41 p.m. EDT. It was from the same active region, No. 1429, that produced flares and coronal mass ejections the entire week. The region has been moving across the face of the Sun since March 2, and will soon rotate out of Earth view.

A solar flare is an intense burst of radiation coming from the release of magnetic energy associated with sunspots. Flares are our solar system’s largest explosive events. They are seen as bright areas on the Sun and last from mere minutes to several hours.

Scientists classify solar flares according to their x-ray brightness. There are 3 categories: X-, M- and C-class. X-class flares are the largest of these events. M-class flares are medium-sized; they can cause brief radio blackouts that affect Earth's polar regions. Compared to X- and M-class, C-class flares are small with few noticeable consequences on Earth.

Photo credit: NASA/SDO

Bright Rays from Canuleia Crater

In this image from NASA's Dawn spacecraft, bright material extends out from the crater Canuleia on Vesta. The bright material appears to have been thrown out of the crater during the impact that created it.

Canuleia crater is located outside the rim of the Rheasilvia basin in the southern hemisphere, inside the quadrangle named for Urbinia crater. It is about 6 miles (10 kilometers) in diameter. The bright ejected material extends 12 to 19 miles (20 to 30 kilometers) beyond the crater's rim.

This image was obtained by Dawn's framing camera on October 25, 2011, during high-altitude mapping orbit (on average 420 miles or 680 kilometers above the surface). This particular image was obtained at an altitude of 435 miles (700 kilometers). It covers about 2,000 square miles (5,000 square kilometers).

Photo credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/UMD

Note: This is only one of fifteen images recently released about features on Vesta. Choosing just one image to highlight on this blog was rather difficult. Be sure to visit the JPL website to view the other fourteen images!

Cygnus Loop Nebula

Wispy tendrils of hot dust and gas glow brightly in this ultraviolet image of the Cygnus Loop nebula, taken by NASA's Galaxy Evolution Explorer. The nebula lies about 1,500 light-years away, and is a supernova remnant, left over from a massive stellar explosion that occurred between 5,000 to 8,000 years ago. The Cygnus Loop extends over three times the size of the full moon in the night sky, and is tucked next to one of the "swan's wings" in the constellation of Cygnus.

The filaments of gas and dust visible here in ultraviolet light were heated by the shockwave from the supernova, which is still spreading outward from the original explosion. The original supernova would have been bright enough to be seen clearly from Earth with the naked eye.

Photo credit: NASA/JPL-Caltech

The Earth from the Moon

This image of the far side of the lunar surface, with Earth in the background, was taken by NASA's MoonKAM system onboard the Ebb spacecraft as part of the first image set taken from lunar orbit from March 15-18, 2012. A little more than half-way up and on the left side of the image is the crater De Forest. Due to its proximity to the southern pole, De Forest receives sunlight at an oblique angle when it is on the illuminated half of the Moon.

MoonKAM (Moon Knowledge Acquired by Middle school students), is led by Sally Ride, America's first woman in space, and her team at Sally Ride Science, in collaboration with undergraduate students at the University of California in San Diego. Over 2,700 schools in 52 countries have signed up to participate in MoonKAM.

Photo credit: NASA/Caltech-JPL/MIT/SRS

Note: For more information, see NASA GRAIL Returns First Student-Selected Moon Images.

COSMOS Deep Field

This view shows a section of the widest deep view of the sky ever taken using infrared light, with a total effective exposure time of 55 hours. It was created by combining more than 6000 individual images from the VISTA survey telescope at ESO’s Paranal Observatory in Chile. This picture shows a region of the sky known as the COSMOS field in the constellation of Sextans (The Sextant). More than 200,000 galaxies have been identified in this picture.

Photo credit: ESO/UltraVISTA team. Acknowledgement: TERAPIX/CNRS/INSU/CASU

Note: For more information, see VISTA Stares Deep into the Cosmos.

Copernicus Crater in Ultraviolet Light

LROC Wide Angle Camera (WAC) visible to ultraviolet portrait of Copernicus Crater, image 458 kilometers (284 miles) wide.

Understanding how scientists determine the relative age of geologic units on the Moon is straightforward, most of the time. One simply follows the law of superposition; what is on top is younger, what is below is older. In some cases, superposition relations are not clear, so scientists then compare crater densities. That is the number of impact craters on a common size of ground. Since impacts occur randomly both in time and on the Moon's surface, any piece of ground has an equal chance of being hit. Over time, the number craters in a given area increases. Simply stated, the older an area the more craters you will find.

Photo credit: NASA/GSFC/Arizona State University

Note: For more information, see Absolute Time.

Planetary System KOI-961

This artist's concept depicts a planetary system so compact that it's more like Jupiter and its moons than a star and its planets. Astronomers using data from NASA's Kepler mission and ground-based telescopes recently confirmed that the system, called KOI-961, hosts the three smallest exoplanets currently known to orbit a star other than our Sun. An exoplanet is a planet that resides outside of our solar system.

The star, which is located about 130 light-years away in the Cygnus constellation, is a red dwarf that is one-sixth the size of the Sun, or just 70 percent bigger than Jupiter. The star is also cooler than our Sun, and gives off more red light than yellow.

The smallest of the three planets, called KOI-961.03, is actually located the farthest from the star, and is pictured in the foreground. This planet is about the size of Mars, with a radius of 0.57 times that of Earth. The next planet to the upper right is KOI-961.01, which is 0.78 times the radius of Earth. The planet closest to the star is KOI-961.02, with a radius 0.73 times the Earth's.

All three planets whip around the star in less than two days, with the closest planet taking less than half a day. Their close proximity to the star also means they are scorching hot, with temperatures ranging from 350 to 836 degrees Fahrenheit (176 to 447 degrees Celsius). The star's habitable zone, or the region where liquid water could exist, is located far beyond the planets.

The ground-based observations contributing to these discoveries were made with the Palomar Observatory, near San Diego, California, and the W.M. Keck Observatory atop Mauna Kea in Hawaii.

Image credit: NASA/JPL-Caltech

Abell 383

Abell 383: A cluster of galaxies located about 2.3 billion light years from Earth.

Two teams of astronomers have used data from Chandra and other telescopes to map the distribution of dark matter in three dimensions in the galaxy cluster Abell 383. The dark matter in Abell 383 is stretched out like a gigantic football with the point of the football aligned close to the line of sight. The X-ray data (purple) from Chandra in the composite image show the hot gas, which is by far the dominant type of normal matter in the cluster. Galaxies are shown with the optical data from the Hubble, the Very Large Telescope, and the Sloan Digital Sky Survey, colored in blue and white.

Scale: Image is 7.26 arcmin across. (4.84 million light years across.)

Photo credit: X-ray: NASA/CXC/Caltech/A.Newman et al/Tel Aviv/A.Morandi & M.Limousin; Optical: NASA/STScI, ESO/VLT, SDSS

Note: For more information, see Abell 383: Getting a Full Picture of an Elusive Subject.

Earth's Gravilty Field Map, Before and After GRACE

Before the launch of NASA's Gravity Recovery and Climate Experiment (GRACE) in 2002, scientists' knowledge of Earth's gravity field was based upon decades of data from geodetic satellites (left image). GRACE has allowed monthly gravity measurements that are more than 100 times more accurate than these previous models, permitting scientists to characterize how Earth's gravity field varies over time and space, as illustrated by the map on the right, produced after just 13 months of GRACE data.

Image credit: NASA/University of Texas Center for Space Research

Note: For more information, see At 10, GRACE Continues Defying, and Defining, Gravity.

Cassiopeia A by WISE

Over 11,000 years ago, a massive, supergiant star came to the end of its life. The star's core collapsed to form an incredibly dense ball of neutrons, and its exterior was blasted away in an immense release of energy astronomers call a supernova.

The light from this supernova first reached Earth from the direction of the constellation Cassiopeia around 1667 A.D. If anyone alive at the time saw it, they left no records. It is likely that large amounts of dust between the dying star and Earth dimmed the brightness of the explosion to the point that it was barely, if at all, visible to the unaided eye.

The remnant of this supernova was discovered in 1947 from its powerful radio emission. Listed as Cassiopeia A, it is one of the brightest radio sources in the whole sky. More recently, the Wide-field Infrared Survey Explorer (WISE), detected infrared echoes of the flash of light rippling outwards from the supernova.

In the image, the central bright cloud of dust is the blast wave moving through interstellar space heating up dust as it goes. The blast wave travels fast -- at an average speed of about 11,000 miles per second (18,000 kilometers per second). By the time WISE took this image, the blast wave has expanded out to about a distance of 21 light-years from the original explosion. The flash of light from the explosion, traveling at the speed of light, has covered well over 300 light-years. The orange-colored echoes further out from the central remnant are from interstellar dust that was heated by the supernova flash centuries after the original explosion.

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

Photo credit: NASA/JPL-Caltech/UCLA

Gravitational Lensing by Quasars

In space, it sometimes happens that two galaxies are aligned in just the right way that the closer galaxy distorts and magnifies the appearance of the one behind it. For astronomers, finding these alignments is like coming across giant, cosmic magnifying glasses.

Now, a team of astronomers, including Daniel Stern from NASA's Jet Propulsion Laboratory in Pasadena, California, has found several rare examples of this phenomenon, called gravitational lensing, in which the foreground galaxy hosts an actively accreting supermassive black hole.

Such feeding black holes, called quasars, are among the brightest objects in the universe, far outshining the total starlight of their host galaxies. Because they are so bright, it is hard for astronomers to measure the mass of their host galaxies. However, gravitational lenses are invaluable for estimating the mass of a quasar's host galaxy. The amount of the background galaxy's distortion can be used to accurately measure the lensing galaxy's mass.

The team hopes to build an even bigger catalog of these quasar lenses, and to use these data to better understand the interplay between black hole feeding and star formation in galaxy evolution.

Photo credit: NASA, ESA, EPFL (Switzerland); text credit: NASA/JPL.

Note: For more information, see Astronomers Using NASA's Hubble Discover Quasars Acting as Gravitational Lenses; for more images, see PIA15418: Quasar Lenses.

Messier 9

This image from the NASA/ESA Hubble Space Telescope shows the globular cluster Messier 9. Hubble's image resolves stars right into the center of the cluster, and clearly shows they have different colors. Redder colors signify lower surface temperatures, while blue stars are extremely hot.

Photo credit: NASA/ESA

Note: For more information, see Glittering Jewels of Messier 9.

Evolution and Tour of the Moon

"Evolution of the Moon" explains why the moon did not always look like it does now. The moon likely started as a giant ball of magma formed from the remains of a collision by a Mars-sized object with the Earth about four and a half billion years ago. After the magma cooled, the moon's crust formed. Then between 4.5 and 4.3 billion years ago, a giant object hit near the moon's South Pole, forming the South Pole-Aitken Basin, one of the two largest proven impact basins in the solar system. This marked the beginning of collisions that would cause large scale changes to the moon's surface, such as the formation of large basins.

Because the moon had not entirely cooled on the inside, magma began to seep through cracks caused by impacts. Around one billion years ago, it's thought that volcanic activity ended on the near side of the moon as the last of the large impacts made their mark on the surface. The moon continued to be battered by smaller impacts. Some of the best-known impacts from this period include the Tycho, Copernicus, and Aristarchus craters. So, while the moon today may seem to be an unchanging world, its appearance is the result of billions of years of violent activity.

"Tour of the Moon" takes viewers to several interesting locations on the moon. Tour stops included in this breathtaking journey across the moon's surface are: Orientale Basin, Shackleton crater, South Pole-Aitken Basin, Tycho crater, Aristarchus Plateau, Mare Serenitatis, Compton-Belkovich volcano, Jackson crater and Tsiolkovsky crater.

Video 1 credit: NASA; video 2 credit: NASA; text credit: NASA.

Teenage Galaxies and the Motions of Their Gas

This deep view of a tiny patch of sky in the constellation of Cetus (The Sea Monster) shows a selection of galaxies that were used in a new survey of the feeding habits of young galaxies as they grew through cosmic time. Each of the tiny blobs, galaxies seen as they were between three and five billion years after the Big Bang, has been studied in detail using ESO’s VLT and the SINFONI instrument. The color maps show the motions of the gas in the galaxies. Blue indicates that the gas is moving towards us, compared to the galaxy as a whole, and red that the gas is receding. These colors allow astronomers to see if the galaxies is rotating like a disc or has some other behavior.

Illustration credit: ESO/CFHT

Note: For more information, see The Feeding Habits of Teenage Galaxies.

Artist's Impression of the Brown Dwarf 2M1207

This illustration shows an artist's impression of the brown dwarf 2MASSW J1207334-393254, or 2M1207 for short. With a mass that amounts to 25 times that of Jupiter, 2M1207 is surrounded by a circumstellar disc of gas and dust and possesses a planetary companion five times more massive than Jupiter. The planetary companion lies at a very large distance from 2M1207 – the projected distance between the two bodies measuring 55 astronomical units (AU).

Sub-millimeter observations performed with the SPIRE instrument on board ESA's Herschel Space Observatory have shown that the disc's total mass amounts to about three to five times the mass of Jupiter and that its radius ranges between 50 and 100 AU. With such a massive disc, it is likely that the planetary-mass companion originated directly from disc fragmentation, thus challenging the standard scenario of giant planet formation via core accretion.

Illustration credit: ESA

Note: For more information, see Herschel's New View on Giant Planet Formation.

Aurora Australis from the ISS

Another amazing capture from ESA astronaut André Kuipers, from his vantage point on the ISS. The Aurora Australis, or Southern Lights, in the high atmosphere between Australia and Antarctica. André traveled to the orbital outpost in December 2011, and will remain in orbit for more than 6 months as part of ESA's long duration mission, PromISSe.

Photo credit: ESA/NASA

NGC 1483

NASA's Hubble Space Telescope has produced this beautiful image of the galaxy NGC 1483. NGC 1483 is a barred spiral galaxy located in the southern constellation of Dorado — the dolphinfish (or Mahi-mahi fish) in Spanish. The nebulous galaxy features a bright central bulge and diffuse arms with distinct star-forming regions. In the background, many other distant galaxies can be seen.

The constellation Dorado is home to the Dorado Group of galaxies, a loose group comprised of an estimated 70 galaxies and located some 62 million light-years away. The Dorado group is much larger than the Local Group that includes the Milky Way (and which contains around 30 galaxies) and approaches the size of a galaxy cluster. Galaxy clusters are the largest groupings of galaxies (and indeed the largest structures of any type) in the universe to be held together by their gravity.

Barred spiral galaxies are so named because of the prominent bar-shaped structures found in their center. They form about two-thirds of all spiral galaxies, including the Milky Way. Recent studies suggest that bars may be a common stage in the formation of spiral galaxies, and may indicate that a galaxy has reached full maturity.

Photo credit: ESA/Hubble & NASA

Star Cluster R136 in the 30 Doradus Nebula

This massive, young stellar grouping, called R136, is only a few million years old and resides in the 30 Doradus Nebula, a turbulent star-birth region in the Large Magellanic Cloud, a satellite galaxy of the Milky Way. There is no known star-forming region in the Milky Way Galaxy as large or as prolific as 30 Doradus.

Many of the diamond-like icy blue stars are among the most massive stars known. Several of them are 100 times more massive than our Sun. These hefty stars are destined to pop off, like a string of firecrackers, as supernovas in a few million years.

The image, taken in ultraviolet, visible and red light by Hubble's Wide Field Camera 3, spans about 100 light-years. The nebula is close enough to Earth that Hubble can resolve individual stars, giving astronomers important information about the stars' birth and evolution.

The brilliant stars are carving deep cavities in the surrounding material by unleashing a torrent of ultraviolet light, and hurricane-force stellar winds (streams of charged particles), which are etching away the enveloping hydrogen gas cloud in which the stars were born. The image reveals a fantasy landscape of pillars, ridges, and valleys, as well as a dark region in the center that roughly looks like the outline of a holiday tree. Besides sculpting the gaseous terrain, the brilliant stars can also help create a successive generation of offspring. When the winds hit dense walls of gas, they create shocks, which may be generating a new wave of star birth.

These observations were taken October 20-27, 2009. The blue color is light from the hottest, most massive stars; the green from the glow of oxygen; the red from fluorescing hydrogen.

Photo credit: NASA, ESA, and F. Paresce (INAF-IASF, Bologna, Italy), R. O'Connell (University of Virginia, Charlottesville), and the Wide Field Camera 3 Science Oversight Committee

Star Birth in Galaxy Centaurus A

Resembling looming rain clouds on a stormy day, dark lanes of dust crisscross the giant elliptical galaxy Centaurus A.

Hubble's panchromatic vision, stretching from ultraviolet through near-infrared wavelengths, reveals the vibrant glow of young, blue star clusters and a glimpse into regions normally obscured by the dust.

The warped shape of Centaurus A's disk of gas and dust is evidence for a past collision and merger with another galaxy. The resulting shockwaves cause hydrogen gas clouds to compress, triggering a firestorm of new star formation. These are visible in the red patches in this Hubble close-up.

At a distance of just over 11 million light-years, Centaurus A contains the closest active galactic nucleus to Earth. The center is home for a supermassive black hole that ejects jets of high-speed gas into space, but neither the supermassive black hole or the jets are visible in this image.

This image was taken in July 2010 with Hubble's Wide Field Camera 3.

Image Credit: NASA, ESA, and the Hubble Heritage (STScI/AURA)-ESA/Hubble

Collaboration Acknowledgment: R. O'Connell (University of Virginia) and the WFC3 Scientific Oversight Committee

Gumdrop Meets Spider

This image, taken on March 6, 1969, shows the Apollo 9 Command and Service Modules docked with the Lunar Module. Apollo 9 astronaut Dave Scott stands in the open hatch of the Command Module, nicknamed "Gumdrop," docked to the Lunar Module "Spider" in Earth orbit. His crewmate Rusty Schweickart, lunar module pilot, took this photograph from the porch of the lunar module. Inside the lunar module was Apollo 9 commander Jim McDivitt. The crew tested the orbital rendezvous and docking procedures that made the lunar landings possible.

Photo credit: NASA

Note: This photo has been one of the Minister's favorites since his childhood; for some reason, this photo has a strong emotional appeal to him. Perhaps it's the red spacehelmet. More astronauts should wear red spacehelmets.

The No Name Nebula

If astronomy had its own Academy Awards, then this part of the Milky Way would have been the "Favorite Nebula" pick for 2011. Competing against 12,263 other slices of the sky, this got more votes from the 35,000 volunteers searching for cosmic bubbles than any other location.

The volunteers are all "citizen scientists" working on the Milky Way Project, scanning a vast collection of infrared images from NASA's Spitzer Space Telescope. Their goal is to identify bubbles that have been blown into gas and dust by stars forming in our Milky Way galaxy. The volunteers study image after image, drawing circles around possible bubbles. Together their efforts have produced a catalog of more than 5,000 bubbles, 10 times what was known before.

While scrutinizing each of the images, the volunteers can bookmark favorite areas. The bright yellow-red nebula at the center of this image garnered the most votes.

Interestingly, this nebula, which is in the constellation of Scutum, has no common name since it is hidden behind dust clouds. It takes an infrared telescope like Spitzer, which sees beyond the visible spectrum of light, to see through this dark veil and reveal this spectacular hidden nebula. Stars can be seen in the process of forming within this audience-favorite nebula, as well in the surrounding areas in this image.

Photo credit: NASA/JPL-Caltech/University of Wisconsin

Note: For another picture and story about the Milky Way Project, see PIA15412: Finding Bubbles in the Milky Way.

Messier 81

The perfectly picturesque spiral galaxy known as Messier 81, or M81, looks sharp in this new composite from NASA's Spitzer and Hubble space telescopes and NASA's Galaxy Evolution Explorer. M81 is a "grand design" spiral galaxy, which means its elegant arms curl all the way down into its center. It is located about 12 million light-years away in the Ursa Major constellation and is one of the brightest galaxies that can be seen from Earth through telescopes.

The colors in this picture represent a trio of light wavelengths: blue is ultraviolet light captured by the Galaxy Evolution Explorer; yellowish white is visible light seen by Hubble; and red is infrared light detected by Spitzer. The blue areas show the hottest, youngest stars, while the reddish-pink denotes lanes of dust that line the spiral arms. The orange center is made up of older stars.

Photo credit: NASA/JPL-Caltech/ESA/Harvard-Smithsonian CfA

The Hercules Cluster of Galaxies

This new image, taken with the VLT Survey Telescope (VST) shows a wide variety of interacting galaxies in the young Hercules galaxy cluster. The sharpness of the picture and the sheer number of objects captured — across a full square degree — in less than three hours of observations attest to the great power of the VST and its OmegaCAM camera to explore the nearby Universe. This picture has been cropped and does not cover the full VST field of view.

Photo credit: ESO/INAF-VST/OmegaCAM. Acknowledgement: OmegaCen/Astro-WISE/Kapteyn Institute

Note: For more information, see Galaxies Get Up Close and Personal.

Beethoven Basin Elevation Map

This elevation map of the Beethoven basin is color-coded to show the height of features on Mercury's surface. Mercury lacks a "sea level," so the zero-point reference elevation is defined to be the mean planetary radius of 2440 km. Blue areas, such as within Bello crater on the floor of Beethoven, have negative elevations. The red and white areas to the southwest are more than 8 km higher than the lowest points in this area.

Center Latitude: -20°
Center Longitude: 236° E
Scale: Beethoven basin is ~650 km (404 miles) in diameter
Image information: A digital terrain model (DTM) derived from Mercury Dual Imaging System (MDIS) stereo images. The lateral spacing is 330 meters and the map is in stereographic (conformal) projection. The image is taken from abstract number 1913 submitted to the 2012 Lunar and Planetary Science Conference, by Frank Preusker and colleagues.

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

Phlegra Montes

Phlegra Montes is a range of gently curving mountains and ridges on Mars. They extend from the northeastern portion of the Elysium volcanic province to the northern lowlands. The High-Resolution Stereo Camera on ESA’s Mars Express collected the data for these images on 1 June 2011 during orbit 9465. The image combines data from the nadir channel and one stereo channel to produce this 3D image. Stereoscopic glasses are required to see the 3D effect.

Photo credit: ESA/DLR/FU Berlin (G. Neukum)

Note: For more information, see Mountains and Buried Ice on Mars.

Dione in False Colors

This view highlights tectonic faults and craters on Dione, an icy world that has undoubtedly experienced geologic activity since its formation.

To create the enhanced-color view, ultraviolet, green and infrared images were combined into a single black and white picture that isolates and maps regional color differences. This "color map" was then superposed over a clear-filter image. The origin of the color differences is not yet understood, but may be caused by subtle differences in the surface composition or the sizes of grains making up the icy soil.

This view looks toward the leading hemisphere on Dione (1,126 kilometers, or 700 miles across). North is up and rotated 20 degrees to the right.

See PIA07690 for a similar monochrome view.

All images were acquired with the Cassini spacecraft narrow-angle camera on December 24, 2005 at a distance of approximately 151,000 kilometers (94,000 miles) from Dione and at a Sun-Dione-spacecraft, or phase, angle of 99 degrees. Image scale is 896 meters (2,940 feet) per pixel.

Photo credit: NASA/JPL/Space Science Institute

Note: For more information, see Cassini Detects Hint of Fresh Air at Dione.

Twin Jets in Herbig-Haro 34

NASA's Spitzer Space Telescope took this image of a baby star sprouting two identical jets (green lines emanating from fuzzy star). The jet on the right had been seen before in visible-light views, but the jet at left -- the identical twin to the first jet -- could only be seen in detail with Spitzer's infrared detectors. The left jet was hidden behind a dark cloud, which Spitzer can see through.

The twin jets, in a system called Herbig-Haro 34, are made of identical knots of gas and dust, ejected one after another from the area around the star. By studying the spacing of these knots, and knowing the speed of the jets from previous studies, astronomers were able to determine that the jet to the right of the star punches its material out 4.5 years later than the counter-jet.

The new data also reveal that the area from which the jets originate is contained within a sphere around the star, with a radius of 3 astronomical units. An astronomical unit is the distance between Earth and the Sun. Previous studies estimated that the maximum size of this jet-making zone was 10 times larger.

The wispy material is gas and dust. Arc-shaped bow shocks can be seen at the ends of the twin jets. The shocks consist of compressed material in front of the jets.

The Herbig-Haro 34 jets are located at approximately 1,400 light-years away in the Orion constellation.

Photo credit: NASA/JPL-Caltech

Abell 520

This composite image shows the distribution of dark matter, galaxies, and hot gas in the core of the merging galaxy cluster Abell 520, formed from a violent collision of massive galaxy clusters.

The natural-color image of the galaxies was taken with NASA's Hubble Space Telescope and with the Canada-France-Hawaii Telescope in Hawaii.

Superimposed on the image are "false-colored" maps showing the concentration of starlight, hot gas, and dark matter in the cluster. Starlight from galaxies, derived from observations by the Canada-France-Hawaii Telescope, is colored orange. The green-tinted regions show hot gas, as detected by NASA's Chandra X-ray Observatory. The gas is evidence that a collision took place. The blue-colored areas pinpoint the location of most of the mass in the cluster, which is dominated by dark matter. Dark matter is an invisible substance that makes up most of the universe's mass. The dark-matter map was derived from the Hubble Wide Field Planetary Camera 2 observations by detecting how light from distant objects is distorted by the cluster of galaxies, an effect called gravitational lensing.

The blend of blue and green in the center of the image reveals that a clump of dark matter resides near most of the hot gas, where very few galaxies are found. This finding confirms previous observations of a dark-matter core in the cluster. The result could present a challenge to basic theories of dark matter, which predict that galaxies should be anchored to dark matter, even during the shock of a collision.

Abell 520 resides 2.4 billion light-years away.

Photo credit: NASA, ESA, CFHT, CXO, M.J. Jee (University of California, Davis), and A. Mahdavi (San Francisco State University)

Note: For more information, see Abell 520: Dark Matter and Galaxies Part Ways in Collision between Hefty Galaxy Clusters .

Earthshine: The Moon Shining in Reflected Light From the Earth

When the Moon appears as a thin crescent in the twilight skies of Earth it is often possible to see that the rest of the disc is also faintly glowing. This phenomenon is called earthshine. It is due to sunlight reflecting off the Earth and illuminating the lunar surface. After reflection from Earth the colors in the light, shown as a rainbow in this picture, are significantly changed. By observing earthshine astronomers can study the properties of light reflected from Earth as if it were an exoplanet and search for signs of life. The reflected light is also strongly polarized and studying the polarization as well as the intensity at different colors allows for much more sensitive tests for the presence of life.

Illustration credit: ESO/L. Calçada; video credit: ESO/M. Kornmesser

Note: For more information, see VLT Rediscovers Life on Earth.

Star Formation in the Orion Nebula

This new view of the Orion Nebula shows embryonic stars within extensive gas and dust clouds. Combining far-infrared observations from the Herschel Space Observatory and mid-infrared observations from NASA's Spitzer Space Telescope, the image shows newly forming stars surrounded by remnant gas and dust in the form of discs and larger envelopes.

Data from the PACS instrument on Herschel at wavelengths of 70 and 160 microns (a micron is a millionth of a meter) are shown as green and red, respectively, and reveal emission from the disks and envelopes of the very youngest protostars. Two Spitzer instruments, IRAC and MIPS, were used to obtain images of the same region at 8 and 24 microns, which are combined here as blue. These wavelengths show emission from the hotter regions of discs around somewhat older stars.

The region shown covers roughly 25x25 arcminutes on the sky or 3x3 parsecs at the distance to Orion.

Photo credits: ESA/PACS/NASA/JPL-Caltech/IRAM

Note: For more information, see Fledgling Stars Flicker in the Heart of Orion; also, Young Stars Flicker Amidst Clouds of Gas and Dust.