Wallpaper World

NOAA�s GOES-East satellite provided a visible-light image of Tropical Storm Harvey on Wednesday, August 30, 2017 at 7:30 a.m. EDT (1230 UTC), hours after it made landfall at 4 a.m. CDT just west of Cameron, Louisiana. At the time of the image, the bulk of showers and thunderstorms around Harvey seemed to stretch from the northern to southwestern quadrants of the storm. Image Credit: NASA/NOAA GOES Project

This spectacular group of young stars is the open star cluster NGC 3766 in the constellation of Centaurus (The Centaur). Very careful observations of these stars by a group from the Geneva Observatory using the Swiss 1.2-metre Leonhard Euler Telescope at ESO�s La Silla Observatory in Chile have shown that 36 of the stars are of a new and unknown class of variable star. This image was taken with the MPG/ESO 2.2-metre telescope at the La Silla Observatory. Image Credit: ESO Explanation from: https://www.eso.org/public/images/eso1326a/

Chandra data show the supermassive black hole at the center of NGC 5813 has erupted multiple times over 50 million years. NGC 5813 is a group of galaxies that is immersed in an enormous reservoir of hot gas. Cavities, or bubbles, in the hot gas that Chandra detects gives information about the black hole's eruptions. Chandra's observations of NGC 5813 are the longest ever of a galaxy group taken in X-ray light. Astronomers have used NASA's Chandra X-ray Observatory to show that multiple eruptions from a supermassive black hole over 50 million years have rearranged the cosmic landscape at the center of a group of galaxies. Scientists discovered this history of black hole eruptions by studying NGC 5813, a group of galaxies about 105 million light years from Earth. These Chandra observations are the longest ever obtained of a galaxy group, lasting for just over a week. The Chandra data are shown in this new composite image where the X-rays from Chandra (purple) have been combin

ISS, Orbit of the Earth August 1, 2017 Image Credit: NASA

This image shows a colour composite of near-infrared images of the central regions of the Orion Nebula, obtained on March 14, 2000, with the SOFI instrument at the ESO 3.5-m New Technology Telescope (NTT) at La Silla. Three exposures were made through J- (wavelength 1.25 �m here colour-coded as "blue"), H- (1.65 �m; "green") and Ks-filters (2.16 �m; "red"), respectively. The central group of bright stars is the famous "Trapezium" . The total effective exposure time was 86.4 seconds per band. The sky field measures about 4.9 x 4.9 arcmin 2 (1024 x 1024 pix 2). Image Credit: ESO Explanation from: https://www.eso.org/public/images/eso0124a/

That galaxies come in very different shapes and sizes is dramatically demonstrated by this striking Hubble image of the Hickson Compact Group 59. Named by astronomer Paul Hickson in 1982, this is the 59th such collection of galaxies in his catalogue of unusually close groups. What makes this image interesting is the variety on display. There are two large spiral galaxies, one face-on with smooth arms and delicate dust tendrils, and one highly inclined, as well as a strangely disorderly galaxy featuring clumps of blue young stars. We can also see many apparently smaller, probably more distant, galaxies visible in the background. Hickson groups display many peculiarities, often emitting in the radio and infrared and featuring active star-forming regions. In addition their galaxies frequently contain Active Galactic Nuclei powered by supermassive black holes, as well large quantities of dark matter. The NASA/ESA Hubble Space Telescope's Advanced Camera for Surveys, using the Wide Fiel

Astronaut Randy Bresnik took this photo of Tropical Storm Harvey from the International Space Station on August 28 at 1:27 p.m. CDT. Image Credit: NASA

After more than four years of observations using the most successful low-mass exoplanet hunter in the world, the HARPS spectrograph attached to the 3.6-metre ESO telescope at La Silla, Chile, astronomers have discovered in this system the lightest exoplanet found so far: Gliese 581e (foreground) is only about twice the mass of our Earth. The Gliese 581 planetary system now has four known planets, with masses of about 1.9 (planet e, left in the foreground), 16 (planet b, nearest to the star), 5 (planet c, centre), and 7 Earth-masses (planet d, with the bluish colour). The planet furthest out, Gliese 581d, orbits its host star in 66.8 days, while Gliese 581 e completes its orbit in 3.15 days. Image Credit: ESO/L. Cal�ada Explanation from: https://www.eso.org/public/images/eso0915a/

These turbulent clouds are on top of the world at Saturn. NASA's Cassini spacecraft captured this view of Saturn's north pole on April 26, 2017 - the day it began its Grand Finale -- as it approached the planet for its first daring dive through the gap between the planet and its rings. Although the pole is still bathed in sunlight at present, northern summer solstice on Saturn occurred on May 24, 2017, bringing the maximum solar illumination to the north polar region. Now the Sun begins its slow descent in the northern sky, which eventually will plunge the north pole into Earth-years of darkness. Cassini's long mission at Saturn enabled the spacecraft to see the Sun rise over the north, revealing that region in great detail for the first time. This view looks toward the sunlit side of the rings from about 44 degrees above the ring plane. The image was taken with the Cassini spacecraft wide-angle camera using a spectral filter which preferentially admits wavelengths of near-

This image was taken by ESO Photo Ambassador Petr Hor�lek, and shows a partial lunar eclipse near its peak, as visible from the roof of the ESO Headquarters in Garching, Germany on 7 August 2017. The entire Moon is turned red by its light scattering through the Earth�s atmosphere. Meanwhile, the bottom right part of the full Moon blends into the sky having entered the umbra of the Earth�s shadow. Image Credit: ESO/P. Hor�lek Explanation from: https://www.eso.org/public/images/potw1733b/

On August 25, 1989, NASA's Voyager 2 made its historic flyby of Neptune and that planet's largest moon Triton. The Cassini mission is publishing this image to celebrate the anniversary of that event. Neptune appears in this natural color composite as a pale blue disk (similar to Cassini's image of Uranus from 2014), just below and to the right of image center. Most of the faint specks in the image are background stars, although some are likely cosmic rays (charged particles that strike the camera detector). A cropped and magnified version is provided in monochrome with Triton visible as a point of light above and to the left of Neptune. In imaging Neptune, Cassini's solar system family portrait-taking is complete. The mission's planetary photojournal includes all of the major planets except Mercury, which is too close to the Sun to be imaged, as well as dwarf planet Pluto. This view was acquired by the Cassini narrow-angle camera on Aug. 10, 2017, at a distance of a

Phenomena across the Universe emit radiation spanning the entire electromagnetic spectrum � from high-energy gamma rays, which stream out from the most energetic events in the cosmos, to lower-energy microwaves and radio waves. Microwaves, the very same radiation that can heat up your dinner, are produced by a multitude of astrophysical sources, including strong emitters known as masers (microwave lasers), even stronger emitters with the somewhat villainous name of megamasers, and the centres of some galaxies. Especially intense and luminous galactic centres are known as active galactic nuclei. They are in turn thought to be driven by the presence of supermassive black holes, which drag surrounding material inwards and spit out bright jets and radiation as they do so. The two galaxies shown here, imaged by the NASA/ESA Hubble Space Telescope, are named MCG+01-38-004 (the upper, red-tinted one) and MCG+01-38-005 (the lower, blue-tinted one). MCG+01-38-005 is a special kind of megamaser;

As millions of people across the United States experienced a total eclipse as the umbra, or Moon�s shadow passed over them, only six people witnessed the umbra from space. Viewing the eclipse from orbit were NASA�s Randy Bresnik, Jack Fischer and Peggy Whitson, ESA (European Space Agency�s) Paolo Nespoli, and Roscosmos� Commander Fyodor Yurchikhin and Sergey Ryazanskiy. The space station crossed the path of the eclipse three times as it orbited above the continental United States at an altitude of 250 miles. Image Credit: NASA Explanation from: https://www.nasa.gov/image-feature/the-eclipse-2017-umbra-viewed-from-space-1

This view from NASA's Cassini spacecraft features a blue planet, but unlike the view from July 19, 2013 that featured our home planet, this blue orb is Uranus, imaged by Cassini for the first time. Uranus is a pale blue in this natural color image because its visible atmosphere contains methane gas and few aerosols or clouds. Methane on Uranus -- and its sapphire-colored sibling, Neptune -- absorbs red wavelengths of incoming sunlight, but allows blue wavelengths to escape back into space, resulting in the predominantly bluish color seen here. Cassini imaging scientists combined red, green and blue spectral filter images to create a final image that represents what human eyes might see from the vantage point of the spacecraft. Uranus has been brightened by a factor of 4.5 to make it more easily visible. The outer portion of Saturn's A ring, seen at bottom right, has been brightened by a factor of two. The bright ring cutting across the image center is Saturn's narrow F ring

This artist�s impression shows the red supergiant star Antares in the constellation of Scorpius. Using ESO�s Very Large Telescope Interferometer astronomers have constructed the most detailed image ever of this, or any star other than the Sun. Using the same data they have also made the first map of the velocities of material the atmosphere of a star other than the Sun. Image Credit: ESO/M. Kornmesser Explanation from: https://www.eso.org/public/images/eso1726b/

This high-resolution image of Juling Crater on Ceres reveals, in exquisite detail, features on the rims and crater floor. The crater is about 1.6 miles (2.5 kilometers) deep and the small mountain, seen left of the center of the crater, is about 0.6 miles (1 kilometers) high. The many features indicative of the flow of material suggest the subsurface is rich in ice. The geological structure of this region, as seen in, also generally suggests that ice is involved. The origin of the small depression seen at the top of the mountain is not fully understood but might have formed as a consequence of a landslide, visible on the northeastern flank. Dawn took this image during its extended mission on August 25, 2016, from its low-altitude mapping orbit at a distance of about 240 miles (385 kilometers) above the surface. The center coordinates of this image are 36 degrees south latitude, 167 degrees east longitude. Juling is named after the Sakai/Orang Asli spirit of the crops from Malaysia. NAS

This visible image of Hurricane Harvey taken from NOAA�s GOES East satellite on August 25 at 10:07 a.m. EDT (1407 UTC) clearly showed the storm�s eye as the storm nears landfall in the southeastern coast of Texas. Image Credit: NASA/NOAA GOES Project

The Copernicus Sentinel-3A satellite saw the temperature at the top of Hurricane Harvey on 25 August 2017 at 04:06 GMT as the storm approached the US state of Texas. The brightness temperature of the clouds at the top of the storm, some 12�15 km above the ocean, range from about �80�C near the eye of the storm to about 20�C at the edges. Hurricanes are one of the forces of nature that can be tracked only by satellites, providing up-to-date imagery so that authorities know when to take precautionary measures. Satellites deliver information on a storm�s extent, wind speed and path, and on key features such as cloud thickness, temperature, and water and ice content. Sentinel-3�s Sea and Land Surface Temperature Radiometer measures energy radiating from Earth�s surface in nine spectral bands and two viewing angles. Image Credit: NASA/ESA Explanation from: http://www.esa.int/spaceinimages/Images/2017/08/Hurricane_Harvey

For more than a month, dozens of large fires have raged in British Columbia. Since early July 2017, wildfire has burned through coniferous forests stressed by heat, drought, and infestations of mountain pine beetles. In early August, another cluster of intense fires flared up in Northwest Territories when a cold front pushed through the region with powerful winds. The intense fires and persistent southerly winds have wafted extraordinary amounts of smoke north over Canada�s Northwest Territories and Yukon and Nunavut provinces. When the Visible Infrared Imaging Radiometer Suite (VIIRS) on Suomi NPP acquired the data for the image above on August 15, 2017, a heavy pall of smoke drifted over northern Canada. The image is a mosaic composed from several satellite overpasses because the affected area is so large. A more detailed view of the fires near Lake Athabasca, captured by the Aqua satellite on August 14, 2017, shows smoke streaming north. That smoke joined with another smoke band fro

This artist's rendering shows a view of our own Milky Way Galaxy and its central bar as it might appear if viewed from above. An arrow indicates the location of our Sun. Astronomers have concluded for many years that our galaxy harbors a stellar bar, though its presence has been inferred indirectly. Our vantage point within the disk of the galaxy makes it difficult to accurately determine the size and shape of this bar and surrounding spiral arms. New observations by the GLIMPSE legacy team with NASA's Spitzer Space Telescope indicate that the bar-shaped collection of old stars at the center of our galaxy may be longer, and at a different orientation, than previously believed. The newly-deduced size and angle of the bar are shown relative to our Sun's location. Our Milky Way galaxy may appear to be very different from an ordinary spiral galaxy. Image Credit: NASA/JPL-Caltech/R. Hurt (SSC) Explanation from: http://www.spitzer.caltech.edu/images/2353-sig05-010a-Milky-Way-Bar

It was spring in the Northern hemisphere when this image was taken on May 21, 2017, at 13:21 local Mars time, by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter. Over the winter, snow and ice have inexorably covered the dunes. Unlike on Earth, this snow and ice is carbon dioxide, better known to us as dry ice. When the Sun starts shining on it in the spring, the ice on the smooth surface of the dune cracks and escaping gas carries dark sand out from the dune below, often creating beautiful patterns. On the rough surface between the dunes, frost is trapped behind small sheltered ridges. Image Credit: NASA/JPL/University of Arizona Explanation from: https://www.nasa.gov/image-feature/jpl/a-world-of-snowy-dunes

Using ESO�s Very Large Telescope Interferometer astronomers have constructed the most detailed image ever of a star � the red supergiant star Antares. They have also made the first map of the velocities of material in the atmosphere of a star other than the Sun, revealing unexpected turbulence in Antares�s huge extended atmosphere. To the unaided eye the famous, bright star Antares shines with a strong red tint in the heart of the constellation of Scorpius (The Scorpion). It is a huge and comparatively cool red supergiant star in the late stages of its life, on the way to becoming a supernova. A team of astronomers, led by Keiichi Ohnaka, of the Universidad Cat�lica del Norte in Chile, has now used ESO�s Very Large Telescope Interferometer (VLTI) at the Paranal Observatory in Chile to map Antares�s surface and to measure the motions of the surface material. This is the best image of the surface and atmosphere of any star other than the Sun. The VLTI is a unique facility that can combin

A total solar eclipse is seen on Monday, August 21, 2017 above Madras, Oregon. A total solar eclipse swept across a narrow portion of the contiguous United States from Lincoln Beach, Oregon to Charleston, South Carolina. A partial solar eclipse was visible across the entire North American continent along with parts of South America, Africa, and Europe. Image Credit: NASA/Aubrey Gemignani Explanation from: https://www.nasa.gov/image-feature/2017-total-solar-eclipse

This image, taken with the NASA/ESA Hubble Space Telescope, shows the galaxy NGC 4490. The scattered and warped appearance of the galaxy are the result of a past cosmic collision with another galaxy, NGC 4485 (not visible in this image). The extreme tidal forces of the interaction between the two galaxies have carved out the shapes and properties of NGC 4490. Once a barred spiral galaxy, the outlying regions of NGC 4490 have been stretched out, resulting in its nickname of the Cocoon Galaxy. Image Credit: ESA/Hubble & NASA Explanation from: https://www.spacetelescope.org/images/heic17xx-ngc4490a/

From a million miles out in space, NASA�s Earth Polychromatic Imaging Camera (EPIC) captured 12 natural color images of the moon�s shadow crossing over North America on Aug. 21, 2017. EPIC is aboard NOAA�s Deep Space Climate Observatory (DSCOVR), where it photographs the full sunlit side of Earth every day, giving it a unique view of total solar eclipses. EPIC normally takes about 20 to 22 images of Earth per day, so this animation appears to speed up the progression of the eclipse. Image Credit: NASA EPIC Team Explanation from: https://www.nasa.gov/image-feature/goddard/2017/nasas-epic-view-of-2017-eclipse-across-america

Clouds on Saturn take on the appearance of strokes from a cosmic brush thanks to the wavy way that fluids interact in Saturn's atmosphere. Neighboring bands of clouds move at different speeds and directions depending on their latitudes. This generates turbulence where bands meet and leads to the wavy structure along the interfaces. Saturn's upper atmosphere generates the faint haze seen along the limb of the planet in this image. This false color view is centered on 46 degrees north latitude on Saturn. The images were taken with the Cassini spacecraft narrow-angle camera on May 18, 2017 using a combination of spectral filters which preferentially admit wavelengths of near-infrared light. The image filter centered at 727 nanometers was used for red in this image; the filter centered at 750 nanometers was used for blue. (The green color channel was simulated using an average of the two filters.) The view was obtained at a distance of approximately 750,000 miles (1.2 million kilom

Gravity governs the movements of the cosmos. It draws flocks of galaxies together to form small groups and more massive galaxy clusters, and brings duos so close that they begin to tug at one another. This latter scenario can have extreme consequences, with members of interacting pairs of galaxies often being dramatically distorted, torn apart, or driven to smash into one another, abandoning their former identities and merging to form a single accumulation of gas, dust, and stars. The subject of this NASA/ESA Hubble Space Telescope image, IC 1727, is currently interacting with its near neighbour, NGC 672 (which is just out of frame). The pair�s interactions have triggered peculiar and intriguing phenomena within both objects � most noticeably in IC 1727. The galaxy�s structure is visibly twisted and asymmetric, and its bright nucleus has been dragged off-centre. In interacting galaxies such as these, astronomers often see signs of intense star formation (in episodic flurries known as s

The last glimmer of the Sun is seen as the Moon makes its final move over the Sun during the total solar eclipse on Monday, August 21, 2017 above Madras, Oregon. A total solar eclipse swept across a narrow portion of the contiguous United States from Lincoln Beach, Oregon to Charleston, South Carolina. A partial solar eclipse was visible across the entire North American continent along with parts of South America, Africa, and Europe. Image Credit: NASA/Aubrey Gemignani Explanation from: https://www.nasa.gov/image-feature/last-glimmer-of-the-sun-above-madras-oregon-during-the-2017-total-solar-eclipse

IC 5148 is a beautiful planetary nebula located some 3000 light-years away in the constellation of Grus (The Crane). The nebula has a diameter of a couple of light-years, and it is still growing at over 50 kilometres per second � one of the fastest expanding planetary nebulae known. The term �planetary nebula� arose in the 19th century, when the first observations of such objects � through the small telescopes available at the time � looked somewhat like giant planets. However, the true nature of planetary nebulae is quite different. When a star with a mass similar to or a few times more than that of our Sun approaches the end of its life, its outer layers are thrown off into space. The expanding gas is illuminated by the hot remaining core of the star at the centre, forming the planetary nebula, which often takes on a beautiful, glowing shape. When observed with a smaller amateur telescope, this particular planetary nebula shows up as a ring of material, with the star � which will coo

This striking Jovian vista was created by citizen scientists Gerald Eichst�dt and Se�n Doran using data from the JunoCam imager on NASA's Juno spacecraft. The tumultuous Great Red Spot is fading from Juno's view while the dynamic bands of the southern region of Jupiter come into focus. North is to the left of the image, and south is on the right. The image was taken on July 10, 2017 at 7:12 p.m. PDT (10:12 p.m. EDT), as the Juno spacecraft performed its seventh close flyby of Jupiter. At the time the image was taken, the spacecraft was 10,274 miles (16,535 kilometers) from the tops of the clouds of the planet at a latitude of -36.9 degrees. Image Credit: NASA/JPL-Caltech/SwRI/MSSS/Gerald Eichstadt/Sean Doran Explanation from: https://photojournal.jpl.nasa.gov/catalog/PIA21778

This composite image shows the progression of a partial solar eclipse over Ross Lake, in Northern Cascades National Park, Washington on Monday, August 21, 2017. A total solar eclipse swept across a narrow portion of the contiguous United States from Lincoln Beach, Oregon to Charleston, South Carolina. A partial solar eclipse was visible across the entire North American continent along with parts of South America, Africa, and Europe. Image Credit: NASA/Bill Ingalls Explanation from: https://www.nasa.gov/image-feature/glory-of-the-heavens

NASA's Cassini gazes across the icy rings of Saturn toward the icy moon Tethys, whose night side is illuminated by Saturnshine, or sunlight reflected by the planet. Tethys was on the far side of Saturn with respect to Cassini here; an observer looking upward from the moon's surface toward Cassini would see Saturn's illuminated disk filling the sky. Tethys was brightened by a factor of two in this image to increase its visibility. A sliver of the moon's sunlit northern hemisphere is seen at top. A bright wedge of Saturn's sunlit side is seen at lower left. This view looks toward the sunlit side of the rings from about 10 degrees above the ring plane. The image was taken in visible light with the Cassini spacecraft wide-angle camera on May 13, 2017. The view was acquired at a distance of approximately 750,000 miles (1.2 million kilometers) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 140 degrees. Image scale is 43 miles (70 kilometers) per pixel on S

NGC 178 may be small, but it packs quite a punch. Measuring around 40 000 light-years across, its diameter is less than half that of the Milky Way, and it is accordingly classified as a dwarf galaxy. Despite its diminutive size, NGC 178 is busy forming new stars. On average, the galaxy forms stars totalling around half the mass of the Sun per year � enough to label it a starburst galaxy. The galaxy�s discovery is an interesting, and somewhat confusing, story. It was originally discovered by American astronomer Ormond Stone in 1885 and dubbed NGC 178, but its position in the sky was recorded incorrectly � by accident the value for the galaxy�s right ascension (which can be thought of as the celestial equivalent of terrestrial longitude) was off by a considerable amount. In the years that followed NGC 178 was spotted again, this time by French astronomer St�phane Javelle. As no catalogued object occupied that position in the sky, Javelle believed he had discovered a new galaxy and entere

One of the most recognizable points on the Earth for astronauts to photograph is the Bahamas, captured in striking images many times from the vantage point of the International Space Station. Expedition 52 Flight Engineer Randy Bresnik of NASA took this photo on Aug. 13, 2017. Image Credit: NASA Explanation from: https://www.nasa.gov/image-feature/space-station-flight-over-the-bahamas

This artist's concept shows a brown dwarf with bands of clouds, thought to resemble those seen at Neptune and the other outer planets. Dim objects called brown dwarfs, less massive than the Sun but more massive than Jupiter, have powerful winds and clouds -- specifically, hot patchy clouds made of iron droplets and silicate dust. Scientists recently realized these giant clouds can move and thicken or thin surprisingly rapidly, in less than an Earth day, but did not understand why. Now, researchers have a new model for explaining how clouds move and change shape in brown dwarfs, using insights from NASA's Spitzer Space Telescope. Giant waves cause large-scale movement of particles in brown dwarfs' atmospheres, changing the thickness of the silicate clouds, researchers report in the journal Science. The study also suggests these clouds are organized in bands confined to different latitudes, traveling with different speeds in different bands. "This is the first time we ha

Chandra observations of the IC 10 starburst galaxy reveal about 110 X-ray sources. Of these, about a dozen are systems where a black hole or neutron star is pulling material away from a young, massive companion star. Some of these pairs may eventually form systems that merge and emit gravitational waves. This new composite contains X-rays from Chandra (dark blue) combined with an optical image from an astrophotographer (red, green, blue). In 1887, American astronomer Lewis Swift discovered a glowing cloud, or nebula, that turned out to be a small galaxy about 2.2 million light years from Earth. Today, it is known as the "starburst" galaxy IC 10, referring to the intense star formationactivity occurring there. More than a hundred years after Swift's discovery, astronomers are studying IC 10 with the most powerful telescopes of the 21st century. New observations with NASA's Chandra X-ray Observatory reveal many pairs of stars that may one day become sources of perhaps t

This illustration shows what the TRAPPIST-1 system might look like from a vantage point near planet TRAPPIST-1f (at right). If we want to know more about whether life could survive on a planet outside our solar system, it�s important to know the age of its star. Young stars have frequent releases of high-energy radiation called flares that can zap their planets' surfaces. If the planets are newly formed, their orbits may also be unstable. On the other hand, planets orbiting older stars have survived the spate of youthful flares, but have also been exposed to the ravages of stellar radiation for a longer period of time. Scientists now have a good estimate for the age of one of the most intriguing planetary systems discovered to date -- TRAPPIST-1, a system of seven Earth-size worlds orbiting an ultra-cool dwarf star about 40 light-years away. Researchers say in a new study that the TRAPPIST-1 star is quite old: between 5.4 and 9.8 billion years. This is up to twice as old as our own

These two views of Saturn's moon Titan exemplify how NASA's Cassini spacecraft has revealed the surface of this fascinating world. Cassini carried several instruments to pierce the veil of hydrocarbon haze that enshrouds Titan. These include the spacecraft's radar and visual and infrared mapping spectrometer, or VIMS. The mission's imaging cameras also have several spectral filters sensitive to specific wavelengths of infrared light that are able to make it through the haze to the surface and back into space. These "spectral windows" have enable the imaging cameras to map nearly the entire surface of Titan. In addition to Titan's surface, images from both the imaging cameras and VIMS have provided windows into the moon's ever-changing atmosphere, chronicling the appearance and movement of hazes and clouds over the years. A large, bright and feathery band of summer clouds can be seen arcing across high northern latitudes in the view at right. These view

This image from the Hubble Space Telescope shows a small galaxy called the Sagittarius dwarf irregular galaxy, or "SagDIG" for short. SagDIG is relatively nearby, and Hubble's sharp vision is able to reveal many thousands of individual stars within the galaxy. The brightest stars in the picture (easily distinguished by the spikes radiating from their images, produced by optical effects within the telescope), are foreground stars lying within our own Milky Way galaxy. Their distances from Earth are typically a few thousand light-years. By contrast, the numerous faint, bluish stars belong to SagDIG, which lies some 3.5 million light-years (1.1 Megaparsecs) from us. Lastly, background galaxies (reddish/brown extended objects with spiral arms and halos) are located even further beyond SagDIG at several tens of millions parsecs away. As their name implies, dwarf irregular galaxies are unlike their spiral and elliptical cousins, because of their much smaller physical size and l

NGC 3628 is a spiral galaxy and a member of a small, but conspicuous group of galaxies located about 35 million light-years away, toward the constellation of Leo (the Lion). The other distinguished members of this family, known collectively as the Leo Triplet, are two well-known prominent spiral galaxies, Messier 65 and Messier 66 (not seen on the image), which were both discovered in 1780 by famous French comet hunter Charles Messier. NGC 3628 is the faintest of the trio and escaped Messier�s observations with his rather small telescope. It was discovered and catalogued by William Herschel only four years later. NGC 3628 hides its spiral structure because it is seen perfectly edge-on, exactly as we observe the Milky Way on a clear night. Its most distinctive feature is a dark band of dust that lies across the plane of the disc and which is visibly distorted outwards, as a consequence of the gravitational interaction between NGC 3628 and its bullying companions. This boxy or �peanut-sh