Wallpaper World

Active regions on the Sun combined to look something like a jack-o-lantern�s face on October 8, 2014. The image was captured by NASA's Solar Dynamics Observatory, or SDO, which watches the Sun at all times from its orbit in space. The active regions in this image appear brighter because those are areas that emit more light and energy. They are markers of an intense and complex set of magnetic fields hovering in the Sun�s atmosphere, the corona. This image blends together two sets of extreme ultraviolet wavelengths at 171 and 193 �ngstr�ms, typically colorized in gold and yellow, to create a particularly Halloween-like appearance. Image Credit: NASA/SDO Explanation from: https://www.nasa.gov/content/goddard/sdo-jack-o-lantern-sun

As the name implies, this reflection nebula associated with the star Rigel looks suspiciously like a fairytale crone. Formally known as IC 2118 in the constellation Orion, the Witch Head Nebula glows primarily by light reflected from the star. The color of this very blue nebula is caused not only by blue color of its star, but also because the dust grains reflect blue light more efficiently than red. A similar physical process causes Earth's daytime sky to appear blue. Image Credit: NASA/STScI Digitized Sky Survey/Noel Carboni Explanation from: https://www.nasa.gov/multimedia/imagegallery/image_feature_1209.html

Described as a "dusty curtain" or "ghostly apparition," mysterious reflection nebula VdB 152 really is very faint. Far from your neighborhood on this Halloween Night, the cosmic phantom is nearly 1,400 light-years away. Also catalogued as Ced 201, it lies along the northern Milky Way in the royal constellation Cepheus. Near the edge of a large molecular cloud, pockets of interstellar dust in the region block light from background stars or scatter light from the embedded bright star giving parts of the nebula a characteristic blue color. Ultraviolet light from the star is also thought to cause a dim reddish luminescence in the nebular dust. Though stars do form in molecular clouds, this star seems to have only accidentally wandered into the area, as its measured velocity through space is very different from the cloud's velocity. This deep telescopic image of the region spans about 7 light-years. Image Credit: Stephen Leshin Explanation from: https://www.nasa.gov/...

Countless galaxies vie for attention in this monster image of the Fornax Galaxy Cluster, some appearing only as pinpricks of light while others dominate the foreground. One of these is the lenticular galaxy NGC 1316. The turbulent past of this much-studied galaxy has left it with a delicate structure of loops, arcs and rings that astronomers have now imaged in greater detail than ever before with the VLT Survey Telescope. This astonishingly deep image also reveals a myriad of dim objects along with faint intracluster light. Captured using the exceptional sky-surveying abilities of the VLT Survey Telescope (VST) at ESO�s Paranal Observatory in Chile, this deep view reveals the secrets of the luminous members of the Fornax Cluster, one of the richest and closest galaxy clusters to the Milky Way. This 2.3-gigapixel image is one of the largest images ever released by ESO. Perhaps the most fascinating member of the cluster is NGC 1316, a galaxy that has experienced a dynamic history, being ...

Brilliant blue stars litter the southern sky and the galactic bulge of our home galaxy, the Milky Way, hangs serenely above the horizon in this spectacular shot of ESO�s Paranal Observatory. This image was taken atop Cerro Paranal in Chile, home to ESO�s Very Large Telescope (VLT). In the foreground, the open dome of one of the four 1.8-metre Auxiliary Telescopes can be seen. The four Auxiliary Telescopes can be utilised together, to form the Very Large Telescope Interferometer (VLTI). The plane of the Milky Way is dotted with bright regions of hot gas. The very bright star towards the upper left corner of the frame is Antares � the brightest star in Scorpius and the fifteenth brightest star in the night sky. Image Credit: ESO/B. Tafreshi Explanation from: https://www.eso.org/public/images/potw1744a/

Stunning views like this image of Saturn's night side are only possible thanks to our robotic emissaries like Cassini. Until future missions are sent to Saturn, Cassini's image-rich legacy must suffice. Because Earth is closer to the Sun than Saturn, observers on Earth only see Saturn's day side. With spacecraft, we can capture views (and data) that are simply not possible from Earth, even with the largest telescopes. This view looks toward the sunlit side of the rings from about 7 degrees above the ring plane. The image was taken in visible light with the wide-angle camera on NASA's Cassini spacecraft on June 7, 2017. The view was obtained at a distance of approximately 751,000 miles (1.21 million kilometers) from Saturn. Image scale is 45 miles (72 kilometers) per pixel. The Cassini spacecraft ended its mission on September 15, 2017. Image Credit: NASA/JPL-Caltech/Space Science Institute Explanation from: https://photojournal.jpl.nasa.gov/catalog/PIA21350

During its flight, the Galileo spacecraft returned images of the Moon. The Galileo spacecraft surveyed the Moon on December 7, 1992, on its way to explore the Jupiter system in 1995-1997. The left part of this north pole view is visible from Earth. This color picture is a mosaic assembled from 18 images taken by Galileo's imaging system through a green filter. The left part of this picture shows the dark, lava-filled Mare Imbrium (upper left); Mare Serenitatis (middle left), Mare Tranquillitatis (lower left), and Mare Crisium, the dark circular feature toward the bottom of the mosaic. Also visible in this view are the dark lava plains of the Marginis and Smythii Basins at the lower right. The Humboldtianum Basin, a 650-kilometer (400-mile) impact structure partly filled with dark volcanic deposits, is seen at the center of the image. The Moon's north pole is located just inside the shadow zone, about a third of the way from the top left of the illuminated region. Image Credit: ...

This NASA/ESA Hubble Space Telescope image is chock-full of galaxies � each glowing speck is a different galaxy, bar the bright flash in the middle of the image which is actually a star lying within our own galaxy that just happened to be in the way. At the centre of the image lies something especially interesting, the centre of the massive galaxy cluster called WHL J24.3324-8.477, including the brightest galaxy of the cluster. The Universe contains structures on various scales � planets collect around stars, stars collect into galaxies, galaxies collect into groups, and galaxy groups collect into clusters. Galaxy clusters contain hundreds to thousands of galaxies bound together by gravity. Dark matter and dark energy play key roles in the formation and evolution of these clusters, so studying massive galaxy clusters can help scientists to unravel the mysteries of these elusive phenomena. This infrared image was taken by Hubble�s Advanced Camera for Surveys and Wide-Field Camera 3 as p...

This color-enhanced image of Jupiter and two of its largest moons -- Io and Europa -- was captured by NASA's Juno spacecraft as it performed its eighth flyby of the gas giant planet. The image was taken on Sept. 1, 2017 at 3:14 p.m. PDT (6:14 p.m. EDT). At the time the image was taken, the spacecraft was about 17,098 miles (27,516 kilometers) from the tops of the clouds of the planet at a latitude of minus 49.372 degrees. Closer to the planet, the Galilean moon of Io can be seen at an altitude of 298,880 miles (481,000 kilometers) and at a spatial scale of 201 miles (324 kilometers) per pixel. In the distance (to the left), another one of Jupiter's Galilean moons, Europa, is visible at an altitude of 453,601 miles (730,000 kilometers) and at a spatial scale of 305 miles (492 kilometers) per pixel. Image Credit: NASA/JPL-Caltech/SwRI/MSSS/Roman Tkachenko Explanation from: https://photojournal.jpl.nasa.gov/catalog/PIA21968

New NASA research is helping to refine our understanding of candidate planets beyond our Solar System that might support life. �Using a model that more realistically simulates atmospheric conditions, we discovered a new process that controls the habitability of exoplanets and will guide us in identifying candidates for further study,� said Yuka Fujii of NASA�s Goddard Institute for Space Studies (GISS), New York, New York and the Earth-Life Science Institute at the Tokyo Institute of Technology, Japan. Previous models simulated atmospheric conditions along one dimension, the vertical. Like some other recent habitability studies, the new research used a model that calculates conditions in all three dimensions, allowing the team to simulate the circulation of the atmosphere and the special features of that circulation, which one-dimensional models cannot do. The new work will help astronomers allocate scarce observing time to the most promising candidates for habitability. Liquid water ...

The elliptical galaxy NGC 4993 is located about 130 million light-years from Earth. On 17 August 2017 the Laser Interferometer Gravitational-Wave Observatory (LIGO) and the Virgo Interferometer both detected gravitational waves from the collision of two neutron stars within this galaxy. The event also resulted in a flare of light, called a kilonova, which is visible to the upper left of the galactic centre in this image from the NASA/ESA Hubble Space Telescope. Image Credit: NASA and ESA Explanation from: https://www.spacetelescope.org/images/heic1717c/

Fomalhaut is one of the brightest stars in the sky. At roughly 25 light-years away the star lies especially close to us, and can be seen shining brightly in the constellation of Piscis Austrinus (The Southern Fish). This image from the Atacama Large Millimeter/submillimeter Array (ALMA) shows Fomalhaut (centre) encircled by a ring of dusty debris � this is the first time this scene has been captured at such high resolution and sensitivity at millimetre wavelengths. Fomalhaut�s disc comprises a mix of cosmic dust and gas from comets in the Fomalhaut system (exocomets), released as the exocomets graze past and smash into one another. This turbulent environment resembles an early period in our own Solar System known as the Late Heavy Bombardment, which occurred approximately four billions years ago. This era saw huge numbers of rocky objects hurtle into the inner Solar System and collide with the young terrestrial planets, including Earth, where they formed a myriad of impact craters � ma...

Looking up at the Moon at night, Earth�s closest neighbor appears in shades of gray and white; a dry desert in the vacuum of space, inactive and dead for billions of years. Like many things, though, with the Moon, there is so much more than what meets the eye. Research completed by NASA Marshall Space Flight Center planetary volcanologist Debra Needham in Huntsville, Alabama, and planetary scientist David Kring at the Lunar and Planetary Institute in Houston, Texas, suggests that billions of years ago, the Moon actually had an atmosphere. The ancient lunar atmosphere was thicker than the atmosphere of Mars today and was likely capable of weathering rocks and producing windstorms. Perhaps most importantly, it could be a source for some, if not all, of the water detected on the Moon. �It just completely changes the way we think of the Moon,� said Needham, a scientist in Marshall�s Science and Technology Office. �It becomes a much more dynamic planetary body to explore.� A time sequence ...

This illustration shows the hot, dense, expanding cloud of debris stripped from two neutron stars just before they collided. Within this neutron-rich debris, large quantities of some of the universe's heaviest elements were forged, including hundreds of Earth masses of gold and platinum. This represents the first time scientists detected light tied to a gravitational-wave event, thanks to two merging neutron stars in the galaxy NGC 4993, located about 130 million light-years from Earth in the constellation Hydra. Image Credit: NASA Goddard Space Flight Center/CI Lab Explanation from: https://www.nasa.gov/image-feature/when-neutron-stars-collide

This image, captured by the NASA/ESA Hubble Space Telescope, shows what happens when two galaxies become one. The twisted cosmic knot seen here is NGC 2623 � or Arp 243 � and is located about 250 million light-years away in the constellation of Cancer (The Crab). NGC 2623 gained its unusual and distinctive shape as the result of a major collision and subsequent merger between two separate galaxies. This violent encounter caused clouds of gas within the two galaxies to become compressed and stirred up, in turn triggering a sharp spike of star formation. This active star formation is marked by speckled patches of bright blue; these can be seen clustered both in the centre and along the trails of dust and gas forming NGC 2623�s sweeping curves (known as tidal tails). These tails extend for roughly 50 000 light-years from end to end. Many young, hot, newborn stars form in bright stellar clusters � at least 170 such clusters are known to exist within NGC 2623. NGC 2623 is in a late stage of...

The NASA/ESA Hubble Space Telescope has observed for the first time the source of a gravitational wave, created by the merger of two neutron stars. This merger created a kilonova � an object predicted by theory decades ago � that ejects heavy elements such as gold and platinum into space. This event also provides the strongest evidence yet that short duration gamma-ray bursts are caused by mergers of neutron stars. This discovery is the first glimpse of multi-messenger astronomy, bringing together both gravitational waves and electromagnetic radiation. On 17 August 2017 the Laser Interferometer Gravitational-Wave Observatory (LIGO) and the Virgo Interferometer both alerted astronomical observers all over the globe about the detection of a gravitational wave event named GW170817. About two seconds after the detection of the gravitational wave, ESA�s INTEGRAL telescope and NASA�s Fermi Gamma-ray Space Telescope observed a short gamma-ray burst in the same direction. In the night followin...

NASA astronaut Joe Acaba photographed Puerto Rico from the cupola of the International Space Station on October 12, 2017. Acaba, whose parents were both born in Puerto Rico, joined NASA as a member of the 2004 class of astronauts and is on his third mission to the space station as a Flight Engineer on the Expedition 53/54 crew. Image Credit: NASA

This image from the Atacama Large Millimeter/submillimeter Array (ALMA) shows V1247 Orionis, a young, hot star surrounded by a dynamic ring of gas and dust, known as a circumstellar disc. This disc can be seen here in two parts: a clearly defined central ring of matter and a more delicate crescent structure located further out. The region between the ring and crescent, visible as a dark strip, is thought to be caused by a young planet carving its way through the disc. As the planet orbits around its parent star, its motion creates areas of high pressure on either side of its path, similar to how a ship creates bow waves as it cuts through water. These areas of high pressure could become protective barriers around sites of planet formation; dust particles are trapped within them for millions of years, allowing them the time and space to clump together and grow. The exquisite resolution of ALMA allows astronomers to study the intricate structure of such a dust trapping vortex for the fir...

This artist�s impression shows two tiny but very dense neutron stars at the point at which they merge and explode as a kilonova. Such a very rare event is expected to produce both gravitational waves and a short gamma-ray burst, both of which were observed on 17 August 2017 by LIGO�Virgo and Fermi/INTEGRAL respectively. Subsequent detailed observations with many ESO telescopes confirmed that this object, seen in the galaxy NGC 4993 about 130 million light-years from the Earth, is indeed a kilonova. Such objects are the main source of very heavy chemical elements, such as gold and platinum, in the Universe. ESO�s fleet of telescopes in Chile have detected the first visible counterpart to a gravitational wave source. These historic observations suggest that this unique object is the result of the merger of two neutron stars. The cataclysmic aftermaths of this kind of merger � long-predicted events called kilonovae � disperse heavy elements such as gold and platinum throughout the Univers...

This image from the VIMOS instrument on ESO�s Very Large Telescope at the Paranal Observatory in Chile shows the galaxy NGC 4993, about 130 million light-years from Earth. The galaxy is not itself unusual, but it contains something never before witnessed, the aftermath of the explosion of a pair of merging neutron stars, a rare event called a kilonova (seen just above and slightly to the left of the centre of the galaxy). This merger also produced gravitational waves and gamma rays, both of which were detected by LIGO-Virgo and Fermi/INTEGRAL respectively. Image Credit: ESO/A.J. Levan, N.R. Tanvir Explanation from: https://www.eso.org/public/images/eso1733b/