A possible scenario for the internal structure of Titan, which includes a global subsurface ocean beneath an icy outer shell, as inferred by radio science data collected by the Cassini spacecraft.
This artist's impression shows exoplanet HD 189733b, as it passes in front of its parent star, called HD 189733A. Hubble's instruments observed the system in 2010, and in 2011 following a large flare from the star (depicted in the image). Following the flare, Hubble observed the planet’s atmosphere evaporating at a rate of over 1000 tonnes per second.
In this picture, the surface of the star, which is around 80% the mass of the Sun, is based on observations of the Sun from the Solar Dynamics Observatory.
The large 25 km-diameter crater in the foreground of this High Resolution Stereo Camera (HRSC) perspective view has excavated rocks which have been altered by groundwater in the crust before the impact occurred. Using OMEGA (Visible and Infrared Mineralogical Mapping Spectrometer) on ESA's Mars Express and CRISM (Compact Reconnaissance Imaging Spectrometer for Mars) on NASA's Mars Reconnaissance Orbiter (MRO), scientists have identified hydrated minerals in the central mound of the crater, on the crater walls and on the large ejecta blanket around the crater. Hydrated minerals were found in 175 locations associated with other nearby craters in the Tyrrhena Terra region of Mars.
This image, taken by NASA's Hubble Space Telescope, show an arc of blue light behind an extremely massive cluster of galaxies residing 10 billion light-years away.
The giant arc is the stretched shape of a more distant star-forming galaxy whose light is distorted by the monster cluster's powerful gravity, an effect called gravitational lensing. The "lensed" galaxy existed 10 billion to 13 billion years ago.
The arc, located within the small box, is barely visible in the Hubble image of the cluster, named IDCS J1426.5+3508. A close-up image of the arc is shown in the inset in Figure 1. The images were taken by Hubble's Advanced Camera for Surveys and Wide Field Camera 3 in 2010.
The cluster is the most massive found at that epoch, weighing as much as 500 trillion suns. The assemblage is 5 to 10 times larger than other clusters found at such an early time in the universe's history. This unique system constitutes the most distant cluster known to "host" a giant gravitationally lensed arc.
A particularly strong jet stream churns through Saturn's northern hemisphere in this false-color view from NASA's Cassini spacecraft.
Clouds associated with the jet stream can be seen in the upper right about a third of the way down from the top of this image. The jet stream clouds appear like a thin, bright orange line here. Moving west and closer to the center of the image, the feature drops south. Farther to the west of this discontinuity, or drop, a blurrier form of the jet stream clouds continues to move along the latitude circle.
See PIA14917 for a closer view and to learn how eddies, or rotating storms, give the jet stream its shape and speed.
The winds of Saturn's jet streams are zonal, meaning they move eastward or westward at particular latitudes. This jet stream is located at about 42 degrees north latitude, and has been visible on Saturn since the days of NASA's Voyager spacecraft (see PIA00027). In the Voyager days, this jet stream had an undulating appearance, leading scientists to dub it the "ribbon wave" (see PIA01378). The planet's atmosphere is always changing, and the jet stream now looks nothing like a ribbon.
Saturn's atmosphere and its rings are shown here in a false color composite made from three images taken in near infrared light through filters that are sensitive to varying degrees of methane absorption. Red and orange colors in this view indicate clouds that are deep in the atmosphere. Yellow and green colors, most noticeable near the top of the view, indicate intermediate clouds. White and blue indicate high clouds and haze.
The white clouds of the equatorial region appear oversaturated because the image was specially processed to bring out the wave.
The rings, in the upper left and lower left of the image, appear bright blue because they are outside of the atmosphere and not affected by methane absorption. This view looks toward the northern, unilluminated side of the rings from about 36 degrees above the ring plane.
The images were taken with the Cassini spacecraft wide-angle camera on January 13, 2008 using a combination of spectral filters sensitive to wavelengths of near-infrared light. The image filtered at 890 nanometers is projected as blue. The image filtered at 728 nanometers is projected as green, and the image filtered at 752 nanometers is projected as red.
The view was acquired at a distance of approximately 810,000 miles (1.3 million kilometers) from Saturn and at a sun-Saturn-spacecraft, or phase, angle of 55 degrees. Image scale is 46 miles (74 kilometers) per pixel.
Astronomers have discovered a pair of neighboring planets with dissimilar densities orbiting very close to each other. The planets are too close to their star to be in the so-called "habitable zone," the region in a star system where liquid water might exist on the surface, but they have the closest orbits between two planets ever confirmed. The findings appear today in the journal Science.
The research team, led by Josh Carter, a Hubble fellow at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., and Eric Agol, a professor of astronomy at the University of Washington in Seattle, used data from NASA's Kepler space telescope, which measures dips in the brightness of more than 150,000 stars, to search for planets.
The inner planet, Kepler-36b, orbits its host star every 13.8 days, and the outer planet, Kepler-36c, every 16.2 days. On their closest approach, the neighboring duo comes within about 1.2 million miles (1.9 million kilometers) of each other. This is only five times the Earth-moon distance and about 20 times closer to each other than any two planets in our solar system.
Kepler-36b is a rocky world measuring 1.5 times the radius, and 4.5 times the mass, of Earth. Kepler-36c is a gaseous giant measuring 3.7 times the radius, and eight times the mass, of Earth. The planetary odd couple orbits a star slightly hotter, and a couple of billion years older, than our sun. The planets are located 1,200 light-years from Earth.
ESO’s Very Large Telescope (VLT) has taken the most detailed image so far of a spectacular part of the stellar nursery called NGC 6357. The view shows many hot young stars, glowing clouds of gas and weird dust formations sculpted by ultraviolet radiation and stellar winds.
The galaxies pictured here have so much dust surrounding them that the brilliant light from their quasars cannot be seen in these images from NASA's Hubble Space Telescope.
Quasars are the brilliant beacons of light that are powered by black holes feasting on captured material, and in the process, heating some of the matter to millions of degrees.
The galaxies are part of a census of 30 quasar host galaxies conducted with two of NASA's premier observatories, the Hubble Space Telescope and Spitzer Space Telescope. They were found in the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS). The study shows that 26 of the host galaxies bear no telltale signs of collisions with neighbors, such as distorted shapes.
The quasars found in normal-looking galaxies are fainter than those powered by collisions between galaxies, which send lots of gas and dust into the gravitational whirlpool of hungry black holes. The dimmer quasars are triggered by black holes snacking on such tasty treats as a batch of gas or the occasional small satellite galaxy. They are the most abundant type of quasar, according to the Hubble analysis.
The images at top right, bottom left, and bottom right reveal three of the survey's normal-looking galaxies that host quasars. Only one galaxy in the sample, at top left, shows evidence of an interaction with another galaxy. The two white blobs are the cores from both galaxies. A streamer of material, colored brown and blue, also lies below the merging galaxies.
The galaxies existed roughly 8 billion to 12 billion years ago, during a peak epoch of black-hole growth. The galaxies' masses are comparable to our Milky Way's. The blue patches are star-forming regions. The brown areas are either dust or old stars.
The images were taken by Hubble's Wide Field Camera 3 between 2011 and 2012.
NASA's Spitzer and Hubble Space Telescopes have 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 infrared and visible-light composite indicates that four monstrously massive stars at the center of the cloud may be the main culprits in the familiar Orion constellation. The stars are collectively called the "Trapezium." 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.
Together, the telescopes expose the stars in Orion as a rainbow of dots sprinkled throughout the image. Orange-yellow dots revealed by Spitzer are actually infant stars deeply embedded in a cocoon of dust and gas. Hubble showed less embedded stars as specks of green, and foreground stars as blue spots.
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.
The Orion constellation is a familiar sight in the fall and winter night sky in the northern hemisphere. The nebula is invisible to the unaided eye, but can be resolved with binoculars or small telescopes.
This image is a false color composite where light detected at wavelengths of 0.43, 0.50, and 0.53 microns is blue. Light at wavelengths of 0.6, 0.65, and 0.91 microns is green. Light at 3.6 microns is orange, and 8.0 microns is red.
Many of the troughs (or, rounded depressions) of Noctis Labyrinthus contain bright, sometimes layered, materials. Noctis Labyrinthus is located on the far western end of the large canyon system Valles Marineris. To the west lie the volcanoes of Tharsis.
This HiRISE image shows an example of the bright material commonly found along the floors of some of the Noctis troughs. Spectral data from the CRISM instrument, also onboard the MRO spacecraft, indicate the bright material is hydrated (i.e., contains water). The hydrated material may have formed when water upwelled into the low-lying depression or when ice within the trough melted due to heating from volcanic activity.
An earlier image taken of this same location will now be combined with this new image to produce a stereo anaglyph. The stereo should allow scientists to understand the relationship between the bright material and the darker rocks that make up the trough floor.
This is a stereo pair with ESP_017399_1680.
The NASA/ESA Hubble Space Telescope has produced an incredibly detailed image of a pair of overlapping galaxies called NGC 3314. While the two galaxies look as if they are in the midst of a collision, this is in fact a trick of perspective: the two are in chance alignment from our vantage point.
This artist's concept shows NASA's two Voyager spacecraft exploring a turbulent region of space known as the heliosheath, the outer shell of the bubble of charged particles around our sun. After more than 33 years of travel, the two Voyager spacecraft will soon reach interstellar space, which is the space between stars.
Our sun gives off a stream of charged particles that form a bubble around our solar system known as the heliosphere. The solar wind travels at supersonic speeds until it crosses a shockwave called the termination shock. That part of our solar system is shown in dark blue. Voyager 1 crossed the termination shock in December 2004 and Voyager 2 did so in August 2007. Beyond the termination shock is the heliosheath, shown in gray, where the solar wind dramatically slows down and heats up. Outside those two areas is territory dominated by the interstellar wind, which is blowing from the left in this image. As the interstellar wind approaches the heliosphere, a bow shock forms, indicated by the bright arc.
NGC 4342 & NGC 4291: Two galaxies, located about 75 million and 85 million light years away respectively, with unusually large central black holes.
Two objects that challenge the prevailing idea of how supermassive black holes grow in the centers of galaxies are shown here. In these composite images, X-rays from Chandra (blue) have been combined with infrared data from 2MASS (red). Both of the black holes at the centers of these galaxies have much larger masses than expected when compared to the galaxies' central bulges of stars. The Chandra data revealed the presence of massive envelopes of dark matter around each galaxy. The new study suggests that the growth of the black holes is closely tied to the amount and distribution of the dark matter in each galaxy, rather than the mass of stars contained in their bulges as previously thought.
Scale: NGC 4342, 6 arcmin across, NGC 4291, 8.4 arcmin across.
This animation of Vesta is made from images taken with Dawn's framing camera. Many of the images were taken at different viewing angles to provide stereo for use in determining the topography. Other images were taken through special infrared and visible light filters in the camera. These infrared and visible light images have been combined and represented in colors that highlight the nature of the minerals on Vesta's surface. Green shows the amount of iron. Scientists have not yet determined the composition indicated by the other colors.
The animation begins overlooking Vesta's north pole and gradually moves southward. The northern polar region is shown as gray because the sun has not yet illuminated this part of Vesta's surface during Dawn's exploration of the asteroid.
It is clear from the wide range of colors that Vesta is very diverse; it is one of the most diversely colored asteroids that has been imaged. The northern troughs can be seen running obliquely from the northern shadows to the Vestan equator. The "snowman" craters Marcia, Calpurnia and Minucia are also clearly visible just north of the equator. Next, the band of equatorial troughs comes into view and Vesta's heavily cratered surface is also displayed. A number of areas of ejecta show a strong red-orange color. As the viewing angle moves towards the southern pole, the large central complex protrudes from the giant Rheasilvia impact basin. The rim and some of the internal structure of the Rheasilvia impact basin are also clearly visible. The Rheasilvia impact basin has a strong greenish appearance here, which signifies a region abundant in iron.
Dawn obtained the images used to make this animation in September and October 2011. The distance to the surface of Vesta is around 420 miles (680 kilometers) on average and the images have an average resolution of about 210 feet (65 meters) per pixel. The color composite mosaic was prepared by the German Aerospace Center. The animation and the topographic model were made by the Planetary Science Institute, Tucson, Arizona.
The Cassini spacecraft takes a close look at a row of craters on Saturn's moon Tethys during the spacecraft's April 14, 2012, flyby of the moon.
Three large craters are visible along the terminator between day and night on Tethys (660 miles, or 1,062 kilometers across). The larger Odysseus crater also can be seen in profile on the right of the image. Odysseus Crater is 280 miles (450 kilometers) across. See PIA07693 for a closer view of Odysseus.
This view looks toward the area between the leading hemisphere and the anti-Saturn side of Tethys. North on Tethys is up and rotated 25 degrees to the right.
The image was taken in visible light with the Cassini spacecraft wide-angle camera on April 14, 2012. The view was acquired at a distance of approximately 12,000 miles (20,000 kilometers) from Tethys and at a Sun-Tethys-spacecraft, or phase, angle of 66 degrees. Image scale is a half mile (1 kilometer) per pixel.
Photo credit:NASA/JPL-Caltech/Space Science Institute
High-Resolution Stereo Camera (HRSC) nadir and color channel data taken on 19 June 2011 by ESA’s Mars Express have been combined to form a natural-color view of the Danielson and Kalocsa craters and their environment in the Arabia Terra region. Centered at around 7°N and 353°E, this image has a ground resolution of about 26 m per pixel. The image shows the yardangs bisected by the darker dune field in Danielson Crater.
This image shows our own back yard, astronomically speaking, from a vantage point about 30 light-years away from the sun. It highlights the population of tiny brown dwarfs recently discovered by NASA's Wide-field Infrared Survey Explorer, or WISE (red circles). The image simulates actual positions of stars.
While big stars like our sun are flashy and easy to see from a distance, astronomers are also interested in our very faintest, smallest neighbors as well. One of the prime objectives of the WISE mission is to find missing "failed stars," or brown dwarfs, in the vicinity of the sun.
Astronomers are interested in brown dwarfs, objects too low in mass to shine stably as stars do, because they have cold atmospheres like those of exoplanets and are some of our nearest neighbors in space. These objects were largely uncharted prior to WISE.
This rendering accurately portrays the relative positions of the sun and its surroundings as they would appear from a vantage point about 30 light-years away. The sun is the faint yellow dot at the very center.
All brown dwarfs known within 26 light-years are circled. Blue circles are previously known brown dwarfs, and red circles are brown dwarfs identified for the first time by WISE.
The slightly larger M-dwarf stars, which are the most common type of star in the solar neighborhood, are shown with enhanced brightness to make them easier to see. They round off the rest of the local collection of objects in this region.
This updated census of our solar neighborhood now shows that brown dwarfs are much more rare than stars: there are roughly 6 stars for every known brown dwarf.
Appearing in the background are the constellation of Orion at middle left and the Pleiades star cluster near the top edge.
Astronomers have uncovered patterns of light that appear to be from the first stars and galaxies that formed in the universe. The light patterns were hidden within a strip of sky observed by NASA's Spitzer Space Telescope.
These two panels show the same slice of sky in the constellation Boötes, dubbed the "Extended Groth Strip." The area covered is about 1 by 0.12 degrees.
The top panel shows Spitzer's initial infrared view of this patch, including foreground stars and a confusion of fainter galaxies, seen at a wavelength of 4.5 microns.
In the lower panel, all of the resolved stars and galaxies have been masked out of the image (grey patches), and the remaining background glow has been smoothed and enhanced. This processing reveals structure too faint to be seen in the original image.
The structure of the lower panel matches just what we would expect for the patterns of clusters from the first galaxies formed in the universe. Even though any particular early galaxy would be too faint to see individually, this technique allows astronomers to better understand what things were like shortly after the Big Bang.
This illustration shows the magnetic environment of Earth, which arises from the interaction between the solar wind, a stream of electrically charged particles released by the Sun, and our planet's internal magnetic field. In fact, the magnetosphere acts as a shield that prevents most of the solar wind particles from infiltrating Earth's atmosphere.
Highlighted in purple are the polar cusps, two regions above the planet's magnetic poles where the magnetic field is extremely weak. Through the cusps, particles from the solar wind can access the upper layer of Earth's atmosphere – the ionosphere – and thus sometimes perturb the propagation of signals through it, disturbing for instance the accuracy of GPS positioning.
In the illustration, the four spacecraft of ESA's Cluster mission are shown as they fly from the magnetosphere into the northern cusp, in the configuration they had on 14 February 2003. This was a very favorable crossing event to study the properties of high-energy particles in the cusp. Using data from this event, scientists have inferred that the particles are accelerated locally, within the cusp, as they cross regions characterized by different electric potential – a configuration shown to result from magnetic reconnection events for this case study.
This image of the Carina Nebula complex, taken with ESA's Herschel Space Observatory at far-infrared wavelengths, shows the intricate network of clouds that make up this prolific cosmic nursery, where tens of thousands of new stars are being formed.
The complex exhibits a rich assortment of bubbles, filaments and pillars. Partly responsible for creating this tangled structure are the numerous high-mass stars hosted within this star-forming region – in the central region alone, the Carina Nebula boasts a census of more than a hundred very massive stars of type O, B and Wolf-Rayet. These mighty stars, which infuse their surroundings with powerful winds and large amounts of ionizing radiation, not only contribute to shaping the nebula's appearance, but also have a significant impact on the star formation activity that takes place within it.
In the central portion of the image, where several stellar clusters host young, massive stars, feedback effects have cleared out the region, and the diffuse material there shines brightly at the shortest of the wavelengths probed by Herschel (hence the blue-white glow that characterizes this portion of the image). The impact of high-mass stars is revealed also in the upper part of the image, where a series of large bubbles have been carved by winds blown by stars at their center. The most prominent of these bubbles, named Gum 31, is visible at the top right corner of the image; it is the result of feedback from massive stars in the young cluster NGC 3324 hosted within the bubble.
At the lower left part of the image a large number of elongated structures, called the Southern Pillars, can be seen. At the base of these pillars, the mixture of gas and dust is extremely dense, highlighting that in this portion of the nebula the feedback from massive stars has caused the material to concentrate in several compact clumps. New generations of stars will eventually emerge from these dense blobs of matter. A pronounced dark region is adjacent to the right edge of the Southern Pillars: the origin of this bubble-like feature is unclear, as the stars hosted there are not massive enough to have sculpted it with winds. Astronomers believe that it might have been caused by gusts of hot gas leaking from the powerful stars at the center of the nebula.
The image combines data acquired with the PACS instrument at 70 micron (shown in blue) and 160 micron (shown in green) and with the SPIRE instrument at 250 micron (shown in red).
CID-42: A galaxy, located nearly 4 billion light years from Earth, with a black hole being ejected from it.
Chandra and other telescopes have shown that the galaxy CID-42 likely contains a massive black hole being ejected at several million miles per hour. The main panel is a wide-field optical image of CID-42 and the area around it. The outlined box represents the more localized view of CID-42 that is shown in the three separate boxes on the right-hand side of the graphic. An image from Chandra (top box) shows that the X-ray emission is concentrated in a single source, corresponding to one of the two sources seen in deep observations by Hubble (middle box). The precise Chandra data helps astronomers narrow their ideas about what is happening in this galaxy, supporting the ejected black hole theory.
Scale: Wide field image is 1 arcmin (1 million light years), Zoom image is 3.7 arcsec across (70,000 light years)
In 1768, when James Cook sailed out of Plymouth harbor to observe the Transit of Venus in Tahiti, the trip was tantamount to a voyage through space. The remote island had just been "discovered" a year earlier, and by all accounts it was as strange and alien to Europeans as the stars themselves. Cook's pinpoint navigation to Tahiti and his subsequent observations of Venus crossing the South Pacific sun in 1769 have inspired explorers for centuries.
One of those explorers is about to beat Cook at his own game.
High above Earth, astronaut Don Pettit is preparing to photograph the June 5th Transit of Venus from space itself.
"I've been planning this for a while," says Pettit, who serves as Flight Engineer onboard the International Space Station. "I knew the Transit of Venus would occur during my rotation, so I brought a solar filter with me when my expedition left for the ISS in December 2011."
Because transits of Venus come in pairs that occur once every 100 years or so, humans have rarely had the chance to photograph the apparition from Earth, much less from Earth orbit.
"The Expedition 31 crew will be the first people in history to see a Venus transit from space, and Pettit will be the first to photograph one," says Mario Runco, Jr. of the Johnson Space Center (JSC). Runco, an astronaut himself who flew aboard three shuttle missions, is an expert in the optics of spacecraft windows. Along with his wife Susan Runco, who is the coordinator for astronaut photography at JSC, Mario is helping Pettit gather the best possible images of the transit.
Pettit will be pointing his camera through the side windows of the space station's cupola, an ESA-built observatory module that provides a wide-angle view of Earth and the cosmos. Its seven windows are used by the crew to operate the station's robotic arm, coordinate space dockings, and take science-grade photos of the Earth and sky. It's also a favorite "hangout" for off-duty astronauts who find the view exhilarating.
"For this transit, Don will be removing the non-optical quality, internal protective window panes known as 'scratch panes,' which really make crisp, sharp, and clear images impossible," says Runco. "Removing those panes is a huge plus when it comes to details that will be seen in the imagery of the sun."
Pettit describes the camera system: "I'll be using a high-end Nikon D2Xs camera and an 800mm lens with a full-aperture white light solar filter."
"Even with this great camera system, the images would be quite soft if the scratch panes were not removed," notes Runco. "This is only the third time that we'll be [shooting through] the Cupola's optical quality windows. I'm hoping this becomes routine in the future."
This month's transit is the bookend of a 2004-2012 pair. Astronauts were onboard the ISS in 2004, but they did not see the transit, mainly because they had no solar filters onboard. Tiny Venus covers a small fraction of the solar disk, so the sun is still painfully bright to the human eye even at mid-transit. Pettit's foresight to bring a solar filter with him makes all the difference.
How would Cook feel about all this?
"I don't think James Cook should be too envious," says Runco. "After all, he did get an all-expense paid trip to Tahiti out of the deal."
Don's photos will be rapidly posted to the web during the transit. The historic webcast begins on June 5th at approximately 3 pm PDT.
As ESA's Rosetta spacecraft flew past the main-belt asteroid (21) Lutetia, the OSIRIS camera on Rosetta surveyed the part of Lutetia that was visible during this period – about half of its entire surface, mostly coinciding with the asteroid's northern hemisphere. The asteroid's North Pole is indicated with a black dot.
The unique, close-up images obtained by OSIRIS have allowed scientists to identify regions characterized by very distinct geological properties with an accuracy of a few hundred meters. By tracing craters and other features on Lutetia's surface, scientists have put together a geological map for the asteroid. Their studies have shown that Lutetia's surface comprises regions spanning a wide range of ages: each of them reveals a chapter in the long and tumultuous history of this asteroid.
The most ancient portions on the surface of Lutetia are the heavily cratered Achaia and Noricum regions, shown in red and yellow in the upper and lower part of the image, respectively. With ages between 3.4 and 3.7 billion years or more, these two regions are almost as old as the asteroid itself.
Massilia, the largest crater identified on the asteroid, is located in a younger region named Narbonensis. This region is shown in blue on the right side of the image: the depression due to the large crater is clearly visible. With a diameter of 57 km, Massilia provides evidence of the most dramatic event in the history of Lutetia.
The youngest patch on the surface of Lutetia is the Baetica region, located in the vicinity of the asteroid's North Pole and shown in green at the center of the image. This region hosts a number of superimposed craters, named the North Polar Crater Cluster (NPCC), which include three large ones with sizes exceeding 10 km. These craters represent the signature left by a series of subsequent impacts that took place quite recently on geological timescales – namely, in the last few hundred million years.
This image shows the spiral galaxy NGC 4151, located at a distance of about 45 million light years from us. NGC 4151 is a Seyfert galaxy and hosts one of the brightest active galactic nuclei (AGN) known at X-ray wavelengths. The supermassive black hole lying at the center of NGC 4151 has a mass of about 50 million solar masses.
Observations performed with ESA's XMM-Newton X-ray observatory have revealed X-rays emitted and then reflected by ionized iron atoms very close to the central black hole. By measuring the time delays occurring in these 'reverberation' events, scientists have been able to map the vicinity of a black hole in unprecedented detail.
This new image of Centaurus A combines ALMA and near-infrared observations of the massive elliptical radio galaxy. The new ALMA observations, shown in a range of green, yellow and orange colors, reveal the position and motion of the clouds of gas in the galaxy. They are the sharpest and most sensitive such observations ever made.
ALMA was tuned to detect signals with a wavelength around 1.3 millimeters, emitted by molecules of carbon monoxide gas. The motion of the gas in the galaxy causes slight changes to this wavelength, due to the Doppler effect. The motion is shown in this image as changes in color. Greener features trace gas coming towards us while more orange features depict gas moving away. We can see that the gas to the left of the center is moving towards us, while the gas to the right of the center is moving away from us, indicating that the gas is orbiting around the galaxy.
The ALMA observations are overlaid on a near-infrared image of Centaurus A obtained with the SOFI instrument attached to the ESO New Technology Telescope (NTT).
ESA's space weather microsatellite Proba-2 observed the solar eclipse on the evening of 20 May 2012. It passed through the Moon's shadow a total of four times, imaging a sequence of partial solar eclipses in the process. The first contact was made on Sunday May 20 at 21:09 GMT. The last contact finished at 03:04 GMT.
