Shell Game in the LMC

An alluring sight in southern skies, the Large Magellanic Cloud (LMC) is seen here through narrowband filters. The filters are designed to transmit only light emitted by ionized sulfur, hydrogen, and oxygen atoms. Ionized by energetic starlight, the atoms emit their characteristic light as electrons are recaptured and the atom transitions to a lower energy state. As a result, this false color image of the LMC seems covered with shell-shaped clouds of ionized gas surrounding massive, young stars. Sculpted by the strong stellar winds and ultraviolet radiation, the glowing clouds, dominated by emission from hydrogen, are known as H II (ionized hydrogen) regions. Itself composed of many overlapping shells, the Tarantula Nebula is the large star forming region at top center. A satellite of our Milky Way Galaxy, the LMC is about 15,000 light-years across and lies a mere 180,000 light-years away in the constellation Dorado. via NASA http://ift.tt/2iIpJL2

Curiosity Surveys Lower Mount Sharp on Mars

If you could stand on Mars -- what might you see? If you were the Curiosity rover, then just last month you would have contemplated the featured image -- a breathtaking panorama of the lower portion of Mount Sharp. The colors have been adjusted to mimic lighting familiar to Earthlings. Surveyed here was a rocky plain before increasingly high rolling hills. The rounded hills in the middle distance, called the Sulfate Unit, are Curiosity's highest currently planned destination. One reason these hills are interesting is because sulfates are an energy source for some micro-organisms. The immediate path forward, though, was toward the southeast on the left part of the image. via NASA http://ift.tt/2hosYXb

The Magnificent Horsehead Nebula

Sculpted by stellar winds and radiation, a magnificent interstellar dust cloud by chance has assumed this recognizable shape. Fittingly named the Horsehead Nebula, it is some 1,500 light-years distant, embedded in the vast Orion cloud complex. About five light-years "tall", the dark cloud is cataloged as Barnard 33 and is visible only because its obscuring dust is silhouetted against the glowing red emission nebula IC 434. Stars are forming within the dark cloud. Contrasting blue reflection nebula NGC 2023, surrounding a hot, young star, is at the lower left. The gorgeous color image combines both narrowband and broadband images recorded using three different telescopes. via NASA http://ift.tt/2i5mZbE

An Airplane Glory

Looking out the window of an airplane, you might be lucky enough to see "the glory" in the direction directly opposite the Sun. Before airplanes, the phenomenon, known to some as the heiligenschein or the Specter of the Brocken, was sometimes seen from mountaintops. There, when conditions were right, one could look away from the Sun and see what appeared to be the shadow of a giant surrounded by a bright halo. The giant turns out to be the observer, as in the modern version a silhouette of an plane frequently occupies the glory's center. This bright glory was photographed two weeks ago over Michigan from an airplane on approach to O'Hare International Airport. The cause of the glory is still being researched and is relatively complex. Surely, small droplets of water in some way reflect, refract, and diffract sunlight backwards towards the Sun. The phenomenon has similar counterparts in other branches of science including astronomy, where looking out from the Earth in the direction opposite the Sun yields a bright spot called the gegenschein. via NASA http://ift.tt/2hVAYR2

Sharpless 308: Star Bubble

Blown by fast winds from a hot, massive star, this cosmic bubble is huge. Cataloged as Sharpless 2-308 it lies some 5,200 light-years away toward the constellation of the Big Dog (Canis Major) and covers slightly more of the sky than a full moon. That corresponds to a diameter of 60 light-years at its estimated distance. The massive star that created the bubble, a Wolf-Rayet star, is the bright one near the center of the nebula. Wolf-Rayet stars have over 20 times the mass of the Sun and are thought to be in a brief, pre-supernova phase of massive star evolution. Fast winds from this Wolf-Rayet star create the bubble-shaped nebula as they sweep up slower moving material from an earlier phase of evolution. The windblown nebula has an age of about 70,000 years. Relatively faint emission captured in the expansive image is dominated by the glow of ionized oxygen atoms mapped to a blue hue. via NASA http://ift.tt/2gXLXYn

Sharpless 308: Star Bubble

Blown by fast winds from a hot, massive star, this cosmic bubble is huge. Cataloged as Sharpless 2-308 it lies some 5,200 light-years away toward the constellation of the Big Dog (Canis Major) and covers slightly more of the sky than a full moon. That corresponds to a diameter of 60 light-years at its estimated distance. The massive star that created the bubble, a Wolf-Rayet star, is the bright one near the center of the nebula. Wolf-Rayet stars have over 20 times the mass of the Sun and are thought to be in a brief, pre-supernova phase of massive star evolution. Fast winds from this Wolf-Rayet star create the bubble-shaped nebula as they sweep up slower moving material from an earlier phase of evolution. The windblown nebula has an age of about 70,000 years. Relatively faint emission captured in the expansive image is dominated by the glow of ionized oxygen atoms mapped to a blue hue. via NASA http://ift.tt/2gXLXYn

Southern Jupiter from Perijove 3

Southern Jupiter looms some 37,000 kilometers away in this JunoCam image from December 11. The image data was captured near Juno's third perijove or closest approach to Jupiter, the spacecraft still in its 53 day long looping orbit. With the south polar region on the left, the large whitish oval toward the right is massive, counterclockwise rotating storm system. Smaller than the more famous Great Red Spot, the oval storm is only about half the diameter of planet Earth, one of a string of white ovals currently in the southern hemisphere of the Solar System's, ruling gas giant. via NASA http://ift.tt/2hZSClv

Seagull to Sirius

This broad, beautiful mosaic spans almost 20 degrees across planet Earth's sky. The nebula-rich region lies near the edge of the Orion-Eridanus superbubble, filled with looping, expanding shells of gas and dust embedded in molecular clouds near the plane of the Milky Way Galaxy. Recognizable at the left is the expansive Seagull Nebula, composed of emission nebula NGC 2327, seen as the seagull's head, with the more diffuse IC 2177 as the wings and body. Some 3,800 light-years away, the wings of the Seagull Nebula spread about 240 light-years, still within our local spiral arm. The bluish light of Sirius, alpha star of Canis Major and brightest star in the night, easily dominates the scene at right but shines from a distance of only 8.6 light-years. Study the big picture and you should also be rewarded with star cluster Messier 41, also known as NGC 2287, not to mention the mighty Thor's Helmet. via NASA http://ift.tt/2hRIH1m

The Lagoon Nebula in High Definition

Stars are battling gas and dust in the Lagoon Nebula but the photographers are winning. Also known as M8, this photogenic nebula is visible even without binoculars towards the constellation of Sagittarius. The energetic processes of star formation create not only the colors but the chaos. The red-glowing gas results from high-energy starlight striking interstellar hydrogen gas. The dark dust filaments that lace M8 were created in the atmospheres of cool giant stars and in the debris from supernovae explosions. The light from M8 we see today left about 5,000 years ago. Light takes about 50 years to cross this section of M8. Data used to compose this image was taken with the wide-field camera OmegaCam of the ESO's VLT Survey Telescope (VST). via NASA http://ift.tt/2hEMAur

Meteors over Four Girl Mountains

On some nights it rains meteors. Peaking over the next two nights, asteroid dust is expected to rain down on Earth during the annual Geminids meteor shower. This year, unfortunately, fainter Geminids will be harder to see because of the brightness of the Long Nights Full Moon, which occurs Wednesday. Pictured, an image from this year's Perseids meteor shower in August captured multiple streaks over Four Girls Mountain in central China. The bright Pleaides open star cluster appears toward the upper right, while numerous emission nebulas are visible in red, many superposed on the diagonal band of the Milky Way. via NASA http://ift.tt/2gHbmsn

Over Saturns Turbulent North Pole

The Cassini spacecraft's Grand Finale at Saturn has begun. The Grand Finale will allow Cassini to explore Saturn and some of Saturn's moons and rings in unprecedented detail. The first phase started two weeks ago when a close flyby of Titan changed Cassini's orbit into one that passes near Saturn's poles and just outside of Saturn's outermost F-ring. Featured here is an image taken during the first of Cassini's 20 week-long F-ring orbits around Saturn. Visible are the central polar vortex on the upper left, a hexagonal cloud boundary through the image center, and numerous light-colored turbulent storm systems. In 2017 April, Cassini will again use the gravity of Titan to begin a new series of 22 Proximal orbits -- trajectories that will take Cassini inside of Saturn's rings for the first time. Cassini's new science adventure is scheduled to end on 2017 September 17, though, when the robotic spacecraft will be directed into a dramatic mission-ending dive into Saturn's atmosphere. via NASA http://ift.tt/2hlvVLX

The Lunar X

The striking X appearing in this lunarscape is easily visible in binoculars or a small telescope. Yet, not too many have seen it. The catch is this lunar X is fleeting, only apparent in the hours before the Moon's first quarter phase. At the terminator, or shadow line between lunar day and night, the X illusion is produced by a configuration of the craters Blanchinus, La Caille and Purbach. Near the Moon's first quarter phase, an astronaut standing close to the craters' position would see the slowly rising Sun very near the horizon. Temporarily, the crater walls would be in sunlight while the crater floors were still in darkness. Seen from planet Earth, contrasting sections of bright walls against the dark floors by chance look remarkably like an X. This sharp image of the Lunar X was captured at approximately 16:45 UT on December 6, 2016. For extra credit, sweep your gaze along the lunar terminator and you can also spot the Lunar V. via NASA http://ift.tt/2hg43Ja

Aurora over Jupiters South Pole from Juno

Why is there a glowing oval over Jupiter's South Pole? Aurora. Near the closest part of its first pass near Jupiter in August, NASA's robotic spacecraft Juno captured this dramatic infrared image of a bright auroral ring. Auroras are caused by high energy particles from the Sun interacting with a planet's magnetic field, and ovals around magnetic poles are common. Data from Juno are giving preliminary indications that Jupiter's magnetic field and aurorae are unexpectedly powerful and complex. Unfortunately, a computer glitch caused Juno to go into safe mode during its last pass near the Jovian giant in September. That glitch has now been resolved, making Juno ready for its next pass over Jupiter's cloud tops this coming Sunday. via NASA http://ift.tt/2h2oM3h

Lightning over Colorado

Have you ever watched a lightning storm in awe? Join the crowd. Oddly, nobody knows exactly how lightning is produced. What is known is that charges slowly separate in some clouds causing rapid electrical discharges (lightning), but how electrical charges get separated in clouds remains a topic of much research. Lightning usually takes a jagged course, rapidly heating a thin column of air to about three times the surface temperature of the Sun. The resulting shock wave starts supersonically and decays into the loud sound known as thunder. Lightning bolts are common in clouds during rainstorms, and on average 44 lightning bolts occur on the Earth every second. Pictured, over 60 images were stacked to capture the flow of lightning-producing storm clouds in July over Colorado Springs, Colorado, USA. via NASA http://ift.tt/2ha4WUe

Galaxies in Pegasus

This wide, sharp telescopic view reveals galaxies scattered beyond the stars of the Milky Way at the northern boundary of the high-flying constellation Pegasus. Prominent at the upper right is NGC 7331. A mere 50 million light-years away, the large spiral is one of the brighter galaxies not included in Charles Messier's famous 18th century catalog. The disturbed looking group of galaxies at the lower left is well-known as Stephan's Quintet. About 300 million light-years distant, the quintet dramatically illustrates a multiple galaxy collision, its powerful, ongoing interactions posed for a brief cosmic snapshot. On the sky, the quintet and NGC 7331 are separated by about half a degree. via NASA http://ift.tt/2g4uUXq

A Triple Star is Born

A triple star system is forming, enshrouded within this dusty natal disk some 750 light-years away in the Perseus molecular cloud. Imaged at millimeter wavelengths by the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, the extreme close-up shows two protostars separated by a mere 61 AU (1 AU is the Earth-Sun distance) with a third 183 AU from the central protostar. The ALMA image also reveals a clear spiral structure indicating instability and fragmentation led to the multiple protostellar objects within the disk. Astronomers estimate that the system, cataloged as L1448 IRS3B, is less than 150,000 years old. Captured at an early phase, the starforming scenario is likely not at all uncommon, since almost half of all sun-like stars have at least one companion. via NASA http://ift.tt/2fOoNI1

Milky Way over Shipwreck

What happened to this ship? It was carried aground by a giant storm that struck the coast of Argentina in 2002. The pictured abandoned boat, dubbed Naufragio del Chubasco, wrecked near the nearly abandoned town of Cabo Raso (population: 1). The rusting ship provides a picturesque but perhaps creepy foreground for the beautiful sky above. This sky is crowned by the grand arch of our Milky Way and features galaxies including the Large and Small Magellanic Clouds, stars including Canopus and Altair, planets including Mars and Neptune, and nebulas including the Lagoon, Carina, and the Coal Sack. The mosaic was composed from over 80 images taken in early September. A 360-degree interactive panoramic version of this image is also available. The adventurous astrophotographer reports that the creepiest part of taking this picture was not the abandoned ship, but the unusual prevalence of black and hairy caterpillars. via NASA http://ift.tt/2gJKk0t

W5: The Soul of Star Formation

Where do stars form? Many times, stars form in energetic regions where gas and dark dust are pushed around in chaotic mayhem. Pictured, bright massive stars near the center of W5, the Soul Nebula, are exploding and emitting ionizing light and energetic winds. The outward-moving light and gas push away and evaporate much surrounding gas and dust, but leave pillars of gas behind dense protective knots. Inside these knots, though, stars also form. The featured image highlights the inner sanctum of W5, an arena spanning about 1,000 light years that is rich in star forming pillars. The Soul Nebula, also cataloged as IC 1848, lies about 6,500 light years away toward the constellation of the Queen of Aethopia (Cassiopeia). Likely, in few hundred million years, only a cluster of the resulting stars will remain. Then, these stars will drift apart. via NASA http://ift.tt/2fxUBRk

Arp 240: A Bridge between Spiral Galaxies from Hubble

Why is there a bridge between these two spiral galaxies? Made of gas and stars, the bridge provides strong evidence that these two immense star systems have passed close to each other and experienced violent tides induced by mutual gravity. Known together as Arp 240 but individually as NGC 5257 and NGC 5258, computer modelling and the ages of star clusters indicate that the two galaxies completed a first passage near each other only about 250 million years ago. Gravitational tides not only pulled away matter, they compress gas and so caused star formation in both galaxies and the unusual bridge. Galactic mergers are thought to be common, with Arp 240 representing a snapshot of a brief stage in this inevitable process. The Arp 240 pair are about 300 million light-years distant and can be seen with a small telescope toward the constellation of Virgo. Repeated close passages should ultimately result in a merger and with the emergence of a single combined galaxy. via NASA http://ift.tt/2gyc9wh

Verona Rupes: Tallest Known Cliff in the Solar System

Could you survive a jump off the tallest cliff in the Solar System? Quite possibly. Verona Rupes on Uranus' moon Miranda is estimated to be 20 kilometers deep -- ten times the depth of the Earth's Grand Canyon. Given Miranda's low gravity, it would take about 12 minutes for a thrill-seeking adventurer to fall from the top, reaching the bottom at the speed of a racecar -- about 200 kilometers per hour. Even so, the fall might be survivable given proper airbag protection. The featured image of Verona Rupes was captured by the passing Voyager 2 robotic spacecraft in 1986. How the giant cliff was created remains unknown, but is possibly related to a large impact or tectonic surface motion. via NASA http://ift.tt/2fnUdoD

Apollo 17 VIP Site Anaglyph

Get out your red/blue glasses and check out this stereo scene from Taurus-Littrow valley on the Moon! The color anaglyph features a detailed 3D view of Apollo 17's Lunar Rover in the foreground -- behind it lies the Lunar Module and distant lunar hills. Because the world was going to be able to watch the Lunar Module's ascent stage liftoff via the rover's TV camera, this parking place was also known as the VIP Site. In December of 1972, Apollo 17 astronauts Eugene Cernan and Harrison Schmitt spent about 75 hours on the Moon, while colleague Ronald Evans orbited overhead. The crew returned with 110 kilograms of rock and soil samples, more than from any of the other lunar landing sites. Cernan and Schmitt are still the last to walk (or drive) on the Moon. via NASA http://ift.tt/2fyv60M

Ring Scan

Scroll right and you can cruise along the icy rings of Saturn. This high resolution scan is a mosaic of images presented in natural color. The images were recorded in May 2007 over about 2.5 hours as the Cassini spacecraft passed above the unlit side of the rings. To help track your progress, major rings and gaps are labeled along with the distance from the center of the gas giant in kilometers. The alphabetical designation of Saturn's rings is historically based on their order of discovery; rings A and B are the bright rings separated by the Cassini division. In order of increasing distance from Saturn, the seven main rings run D,C,B,A,F,G,E. (Faint, outer rings G and E are not imaged here.) Four days from now, on November 29, Cassini will make a close flyby of Saturn's moon Titan and use the large moon's gravity to nudge the spacecraft into a series of 20 daring, elliptical, ring-grazing orbits. Diving through the ring plane just 11,000 kilometers outside the F ring (far right) Cassini's first ring-graze will be on December 4. via NASA http://ift.tt/2fbgea1

Plutos Sputnik Planum

Is there an ocean below Sputnik Planum on Pluto? The unusually smooth 1000-km wide golden expanse, visible in the featured image from New Horizons, appears segmented into convection cells. But how was this region created? One hypothesis now holds the answer to be a great impact that stirred up an underground ocean of salt water roughly 100-kilometers thick. The featured image of Sputnik Planum, part of the larger heart-shaped Tombaugh Regio, was taken last July and shows true details in exaggerated colors. Although the robotic New Horizons spacecraft is off on a new adventure, continued computer-modeling of this surprising surface feature on Pluto is likely to lead to more refined speculations about what lies beneath. via NASA http://ift.tt/2ghUTco

Nova over Thailand

A nova in Sagittarius is bright enough to see with binoculars. Detected last month, the stellar explosion even approached the limit of naked-eye visibility last week. A classical nova results from a thermonuclear explosion on the surface of a white dwarf star -- a dense star having the size of our Earth but the mass of our Sun. In the featured image, the nova was captured last week above ancient Wat Mahathat in Sukhothai, Thailand. To see Nova Sagittarius 2016 yourself, just go out just after sunset and locate near the western horizon the constellation of the Archer (Sagittarius), popularly identified with an iconic teapot. Also visible near the nova is the very bright planet Venus. Don’t delay, though, because not only is the nova fading, but that part of the sky is setting continually closer to sunset. via NASA http://ift.tt/2gBQ3dz

NGC 4414: A Flocculent Spiral Galaxy

How much mass do flocculent spirals hide? The featured true color image of flocculent spiral galaxy NGC 4414 was taken with the Hubble Space Telescope to help answer this question. The featured image was augmented with data from the Sloan Digital Sky Survey (SDSS). Flocculent spirals -- galaxies without well-defined spiral arms -- are a quite common form of galaxy, and NGC 4414 is one of the closest. Stars and gas near the visible edge of spiral galaxies orbit the center so fast that the gravity from a large amount of unseen dark matter must be present to hold them together. Understanding the matter and dark matter distribution of NGC 4414 helps humanity calibrate the rest of the galaxy and, by deduction, flocculent spirals in general. Further, calibrating the distance to NGC 4414 helps humanity calibrate the cosmological distance scale of the entire visible universe. via NASA http://ift.tt/2gsbMns

Philadelphia Perigee Full Moon

A supermoon sets over the metropolis of Philadelphia in this twilight snapshot captured on November 14 at 6:21am Eastern Standard Time. Within hours of the Moon's exact full phase, that time does correspond to a lunar perigee or the closest point in the Moon's elliptical orbit around our fair planet. Slightly bigger and brighter at perigee, this Full Moon is still flattened and distorted in appearance by refraction in atmospheric layers along the sight-line near the horizon. Also like more ordinary Full Moons, it shines with the warm color of sunlight. Joined by buildings along the Philadelphia skyline, the perigee full moonlight is reflected in the waters of the mighty Cooper River. via NASA http://ift.tt/2f7q2wQ

Super Moon vs Micro Moon

What is so super about tomorrow's supermoon? Tomorrow, a full moon will occur that appears slightly larger and brighter than usual. The reason is that the Moon's fully illuminated phase occurs within a short time from perigee - when the Moon is its closest to the Earth in its elliptical orbit. Although the precise conditions that define a supermoon vary, tomorrow's supermoon will undoubtedly qualify because it will be the closest, largest, and brightest full moon in over 65 years. One reason supermoons are popular is because they are so easy to see -- just go outside at sunset and watch an impressive full moon rise! Since perigee actually occurs tomorrow morning, tonight's full moon, visible starting at sunset, should also be impressive. Pictured here, a supermoon from 2012 is compared to a micromoon -- when a full Moon occurs near the furthest part of the Moon's orbit -- so that it appears smaller and dimmer than usual. Given many definitions, at least one supermoon occurs each year, with another one coming next month (moon-th). However, a full moon will not come this close to Earth again until 2034. via NASA http://ift.tt/2fvYgeM

NGC 7822 in Cepheus

Hot, young stars and cosmic pillars of gas and dust seem to crowd into NGC 7822. At the edge of a giant molecular cloud toward the northern constellation Cepheus, the glowing star forming region lies about 3,000 light-years away. Within the nebula, bright edges and dark shapes stand out in this colorful skyscape. The image includes data from narrowband filters, mapping emission from atomic oxygen, hydrogen, and sulfur into blue, green, and red hues. The emission line and color combination has become well-known as the Hubble palette. The atomic emission is powered by energetic radiation from the central hot stars. Their powerful winds and radiation sculpt and erode the denser pillar shapes and clear out a characteristic cavity light-years across the center of the natal cloud. Stars could still be forming inside the pillars by gravitational collapse but as the pillars are eroded away, any forming stars will ultimately be cutoff from their reservoir of star stuff. This field of view spans over 40 light-years at the estimated distance of NGC 7822. via NASA http://ift.tt/2fqqCap

The Cosmic Web of the Tarantula Nebula

It is the largest and most complex star forming region in the entire galactic neighborhood. Located in the Large Magellanic Cloud, a small satellite galaxy orbiting our Milky Way galaxy, the region's spidery appearance is responsible for its popular name, the Tarantula nebula. This tarantula, however, is about 1,000 light-years across. Were it placed at the distance of Milky Way's Orion Nebula, only 1,500 light-years distant and the nearest stellar nursery to Earth, it would appear to cover about 30 degrees (60 full moons) on the sky. Intriguing details of the nebula are visible in the featured image shown in colors emitted predominantly by hydrogen and oxygen. The spindly arms of the Tarantula nebula surround NGC 2070, a star cluster that contains some of the brightest, most massive stars known, visible in blue in the image center. Since massive stars live fast and die young, it is not so surprising that the cosmic Tarantula also lies near the site of the closest recent supernova. via NASA http://ift.tt/2fz5At0

Inverted City Beneath Clouds

How could that city be upside-down? The city, Chicago, was actually perfectly right-side up. The long shadows it projected onto nearby Lake Michigan near sunset, however, when seen in reflection, made the buildings appear inverted. This fascinating, puzzling, yet beautiful image was captured by a photographer in 2014 on an airplane on approach to Chicago's O'Hare International Airport. The Sun can be seen both above and below the cloud deck, with the latter reflected in the calm lake. As a bonus, if you look really closely -- and this is quite a challenge -- you can find another airplane in the image, likely also on approach to the same airport. via NASA http://ift.tt/2frZ98z

Starburst Cluster in NGC 3603

A mere 20,000 light-years from the Sun lies NGC 3603, a resident of the nearby Carina spiral arm of our Milky Way Galaxy. NGC 3603 is well known to astronomers as one of the Milky Way's largest star-forming regions. The central open star cluster contains thousands of stars more massive than our Sun, stars that likely formed only one or two million years ago in a single burst of star formation. In fact, nearby NGC 3603 is thought to contain a convenient example of the massive star clusters that populate much more distant starburst galaxies. Surrounding the cluster are natal clouds of glowing interstellar gas and obscuring dust, sculpted by energetic stellar radiation and winds. Recorded by the Hubble Space Telescope, the image spans about 17 light-years. via NASA http://ift.tt/2erW06L

Ghost Aurora over Canada

What does this aurora look like to you? While braving the cold to watch the skies above northern Canada early one morning in 2013, a most unusual aurora appeared. The aurora definitely appeared to be shaped like something , but what? Two ghostly possibilities recorded by the astrophotographer were "witch" and "goddess of dawn", but please feel free to suggest your own Halloween-enhanced impressions. Regardless of fantastical pareidolic interpretations, the pictured aurora had a typical green color and was surely caused by the scientifically commonplace action of high energy particles from space interacting with oxygen in Earth's upper atmosphere. In the image foreground, at the bottom, is a frozen Alexandra Falls, while evergreen trees cross the middle. via NASA http://ift.tt/2f4lSIh

Halloween and the Ghost Head Nebula

Halloween's origin is ancient and astronomical. Since the fifth century BC, Halloween has been celebrated as a cross-quarter day, a day halfway between an equinox (equal day / equal night) and a solstice (minimum day / maximum night in the northern hemisphere). With a modern calendar however, even though Halloween occurs tomorrow, the real cross-quarter day will occur next week. Another cross-quarter day is Groundhog Day. Halloween's modern celebration retains historic roots in dressing to scare away the spirits of the dead. Perhaps a fitting tribute to this ancient holiday is this view of the Ghost Head Nebula taken with the Hubble Space Telescope. Similar to the icon of a fictional ghost, NGC 2080 is actually a star forming region in the Large Magellanic Cloud, a satellite galaxy of our own Milky Way Galaxy. The Ghost Head Nebula spans about 50 light-years and is shown in representative colors. via NASA http://ift.tt/2fjzIda

Haunting the Cepheus Flare

Spooky shapes seem to haunt this jeweled expanse, drifting through the night in the royal constellation Cepheus. Of course, the shapes are cosmic dust clouds faintly visible in dimly reflected starlight. Far from your own neighborhood on planet Earth, they lurk along the plane of the Milky Way at the edge of the Cepheus Flare molecular cloud complex some 1,200 light-years away. Over 2 light-years across and brighter than the other ghostly apparitions, vdB 141 or Sh2-136 is also known as the Ghost Nebula, seen at the right of the starry field of view. Within the nebula are the telltale signs of dense cores collapsing in the early stages of star formation. via NASA http://ift.tt/2fe2onB

Clouds Near Jupiters South Pole from Juno

What's happening near the south pole of Jupiter? Recent images sent back by NASA's robotic Juno spacecraft are showing an interesting conglomeration of swirling clouds and what appear to be white ovals. Juno arrived at Jupiter in July and is being placed into a wide, looping orbit that will bring it near the gas giant -- and over its poles -- about twice a month. The featured image is a composite taken by JunoCam and post-processed by a digitally savvy citizen scientist. White ovals have been observed elsewhere on Jupiter and are thought to be giant storm systems. They have been observed to last for years, while typically showing Category 5 wind speeds of around 350 kilometers per hour. Unlike Earthly cyclones and hurricanes where high winds circle regions of low pressure, white ovals on Jupiter show rotational directions indicating that they are anticylones -- vortices centered on high pressure regions. Juno will continue to orbit Jupiter over thirty more times while recording optical, spectral, and gravitational data meant to help determine Jupiter's structure and evolution. via NASA http://ift.tt/2eHnAz7

Eagle Aurora over Norway

What's that in the sky? An aurora. A large coronal mass ejection occurred on our Sun five days before this 2012 image was taken, throwing a cloud of fast moving electrons, protons, and ions toward the Earth. Although most of this cloud passed above the Earth, some of it impacted our Earth's magnetosphere and resulted in spectacular auroras being seen at high northern latitudes. Featured here is a particularly photogenic auroral corona captured above Grotfjord, Norway. To some, this shimmering green glow of recombining atmospheric oxygen might appear as a large eagle, but feel free to share what it looks like to you. Although now past Solar Maximum, our Sun continues to show occasional activity creating impressive auroras on Earth visible only last week. via NASA http://ift.tt/2eu9S4j

The Tulip in the Swan

Framing a bright emission region this telescopic view looks out along the plane of our Milky Way Galaxy toward the nebula rich constellation Cygnus the Swan. Popularly called the Tulip Nebula, the glowing cloud of interstellar gas and dust is also found in the 1959 catalog by astronomer Stewart Sharpless as Sh2-101. About 8,000 light-years distant and 70 light-years across the complex and beautiful nebula blossoms at the center of the composite image. Red, green, and blue hues map emission from ionized sulfur, hydrogen, and oxygen atoms. Ultraviolet radiation from young, energetic stars at the edge of the Cygnus OB3 association, including O star HDE 227018, ionizes the atoms and powers the visible light emission from the Tulip Nebula. HDE 227018 is the bright star very near the blue arc at the center of the cosmic tulip. via NASA http://ift.tt/2dCMLmV

M45: The Pleiades Star Cluster

Have you ever seen the Pleiades star cluster? Even if you have, you probably have never seen it as dusty as this. Perhaps the most famous star cluster on the sky, the bright stars of the Pleiades can be seen without binoculars even from the heart of a light-polluted city. With a long exposure from a dark location, though, the dust cloud surrounding the Pleiades star cluster becomes very evident. The featured image was a long duration exposure taken last month from Namibia and covers a sky area many times the size of the full moon. Also known as the Seven Sisters and M45, the Pleiades lies about 400 light years away toward the constellation of the Bull (Taurus). A common legend with a modern twist is that one of the brighter stars faded since the cluster was named, leaving only six stars visible to the unaided eye. The actual number of visible Pleiades stars, however, may be more or less than seven, depending on the darkness of the surrounding sky and the clarity of the observer's eyesight. via NASA http://ift.tt/2el3RF8

The Antlia Cluster of Galaxies

Galaxies dot the sky in this impressively wide and deep image of the Antlia Cluster. The third closest cluster of galaxies to Earth after Virgo and Fornax, the Antlia cluster is known for its compactness and its high fraction of elliptical galaxies over (spirals. Antlia, cataloged as Abell S0636, spans about 2 million light years and lies about 130 million light years away toward the constellation of the Air Pump (Antlia). The cluster has two prominent galaxy groups - bottom center and upper left -- among its over 200 galactic members, but no single central dominant galaxy. The vertical red ribbon of gas on the left is thought related to the foreground Antlia supernova remnant and not associated with the cluster. The featured image composite, taken from New Zealand, resulted from 150+ hours of exposures taken over six months. via NASA http://ift.tt/2egQ4iQ

Cylindrical Mountains on Venus

What could cause a huge cylindrical mountain to rise from the surface of Venus? Such features that occur on Venus are known as coronas. Pictured here in the foreground is 500-kilometer wide Atete Corona found in a region of Venus known as the Galindo. The featured image was created by combining multiple radar maps of the region to form a computer-generated three-dimensional perspective. The series of dark rectangles that cross the image from top to bottom were created by the imaging procedure and are not real. The origin of massive coronas remains a topic of research although speculation holds they result from volcanism. Studying Venusian coronas help scientists better understand the inner structure of both Venus and Earth. via NASA http://ift.tt/2e9hMOr

Herschel s Orion

This dramatic image peers within M42, the Orion Nebula, the closest large star-forming region. Using data at infrared wavelengths from the Herschel Space Observatory, the false-color composite explores the natal cosmic cloud a mere 1,500 light-years distant. Cold, dense filaments of dust that would otherwise be dark at visible wavelengths are shown in reddish hues. Light-years long, the filaments weave together bright spots that correspond to regions of collapsing protostars. The brightest bluish area near the top of the frame is warmer dust heated by the hot Trapezium cluster stars that also power the nebula's visible glow. Herschel data has recently indicated ultraviolet starlight from the hot newborn stars likely contributes to the creation of carbon-hydrogen molecules, basic building blocks of life. This Herschel image spans about 3 degrees on the sky. That's about 80 light-years at the distance of the Orion Nebula. via NASA http://ift.tt/2efmMkj

Galaxies from the Altiplano

The central bulge of our Milky Way Galaxy rises over the northern Chilean Atacama altiplano in this postcard from planet Earth. At an altitude of 4500 meters, the strange beauty of the desolate landscape could almost belong to another world though. Brownish red and yellow tinted sulfuric patches lie along the whitish salt flat beaches of the Salar de Aguas Calientes region. In the distance along the Argentina border is the stratovolcano Lastarria, its peak at 5700 meters (19,000 feet). In the clear, dark sky above, stars, nebulae, and cosmic dust clouds in the Milky Way echo the colors of the altiplano at night. Extending the view across extragalactic space, the Large and Small Magellanic Clouds, satellite galaxies of the Milky Way, shine near the horizon through a faint greenish airglow. via NASA http://ift.tt/2dP2QJ4

The Hydrogen Clouds of M33

Gorgeous spiral galaxy M33 seems to have more than its fair share of glowing hydrogen gas. A prominent member of the local group of galaxies, M33 is also known as the Triangulum Galaxy and lies about 3 million light-years distant. The galaxy's inner 30,000 light-years or so are shown in this telescopic portrait that enhances its reddish ionized hydrogen clouds or HII regions. Sprawling along loose spiral arms that wind toward the core, M33's giant HII regions are some of the largest known stellar nurseries, sites of the formation of short-lived but very massive stars. Intense ultraviolet radiation from the luminous, massive stars ionizes the surrounding hydrogen gas and ultimately produces the characteristic red glow. To enhance this image, broadband data was used to produce a color view of the galaxy and combined with narrowband data recorded through a hydrogen-alpha filter. That filter transmits the light of the strongest visible hydrogen emission line. via NASA http://ift.tt/2d8nO2o

Trifid, Lagoon, and Mars

Bright nebulae and star clusters along this 5 degree wide field of view are popular stops on telescopic tours of the constellation Sagittarius and the crowded starfields of the central Milky Way. Cataloged by 18th century French astronomer Charles Messier, M20, the colorful Trifid Nebula, and M8, the expansive Lagoon Nebula, are at upper left and center. Both are well-known star forming regions about 5,000 light-years distant. Just passing through the same field of view on September 29, the yellowish star lined up with M8 and M20 at the lower right is actually Mars, close to 8.8 light-minutes from Earth on that date. That distance is nearly equivalent to 1 astronomical unit or the distance from Earth to Sun. Mars is overexposed in the image, with visible diffraction spikes created by the telescope mirror supports. Of course, Mars has long been known to wander through planet Earth's night skies. via NASA http://ift.tt/2dOpssR

A Crumbling Layered Butte on Mars

What is this unusual mound on Mars? NASA's Curiosity rover rolling across Mars has come across a group of these mounds that NASA has labelled Murray Buttes. Pictured is a recently assembled mosaic image of one of the last of the buttes passed by Curiosity on its way up Mt. Sharp -- but also one of the most visually spectacular. Ancient water-deposited layers in relatively dense -- but now dried-out and crumbling -- windblown sandstone tops the 15-meter tall structure. The rim of Gale crater is visible in the distance. Curiosity continues to accumulate clues about how Mars changed from a planet with areas wet and hospitable to microbial life to the dry, barren, rusted landscape seen today. via NASA http://ift.tt/2cSWFNv

Nest of the Eagle Nebula

What surrounds the famous Eagle Nebula? The inside of the Eagle Nebula contains eggs -- evaporating gaseous globules -- that typically reside in tremendous pillars of gas and dust and where stars form. This image, though, dramatically captures the area surrounding the Eagle Nebula, showing not only the entire Eagle shape, but also enormous volumes of glowing gas and dark dust. Cataloged as M16, the Eagle emission nebula lies about 6,500 light years away and is visible with binoculars toward the constellation of the Serpent (Serpens). The image spans about 80 light years around the nebula. The iconic center of the Eagle Nebula has been the focus of many observational efforts both from the ground and orbiting observatories. via NASA http://ift.tt/2d06Tz3

Aurora Over White Dome Geyser

Sometimes both heaven and Earth erupt. Colorful aurorae erupted unexpectedly a few years ago, with green aurora appearing near the horizon and brilliant bands of red aurora blooming high overhead. A bright Moon lit the foreground of this picturesque scene, while familiar stars could be seen far in the distance. With planning, the careful astrophotographer shot this image mosaic in the field of White Dome Geyser in Yellowstone National Park in the western USA. Sure enough, just after midnight, White Dome erupted -- spraying a stream of water and vapor many meters into the air. Geyser water is heated to steam by scalding magma several kilometers below, and rises through rock cracks to the surface. About half of all known geysers occur in Yellowstone National Park. Although the geomagnetic storm that created these aurorae has since subsided, eruptions of White Dome Geyser continue about every 30 minutes. via NASA http://ift.tt/2dmTiBm

Rosetta s Farewell

After closely following comet 67P/Churyumov-Gerasimenko for 786 days as it rounded the Sun, the Rosetta spacecraft's controlled impact with the comet's surface was confirmed by the loss of signal from the spacecraft on September 30, 2016. One the images taken during its final descent, this high resolution view looks across the comet's stark landscape. The scene spans just over 600 meters (2,000 feet), captured when Rosetta was about 16 kilometers from the comet's surface. Rosetta's descent to the comet brought to an end the operational phase of an inspirational mission of space exploration. Rosetta deployed a lander to the surface of one of the Solar System's most primordial worlds and witnessed first hand how a comet changes when subject to the increasing intensity of the Sun's radiation. The decision to end the mission on the surface is a result of the comet's orbit now taking it to the dim reaches beyond Jupiter where there would be a lack of power to operate the spacecraft. Mission operators also faced an approaching period where the Sun would be close to line-of-sight between Earth and Rosetta, making radio communications increasingly difficult. via NASA http://ift.tt/2cIZosW

Five Hundred Meter Aperture Spherical Telescope

The Five-hundred-meter Aperture Spherical Telescope (FAST) is nestled within a natural basin in China's remote and mountainous southwestern Guizhou province. Nicknamed Tianyan, or the Eye of Heaven, the new radio telescope is seen in this photograph taken near the start of its testing phase of operations on September 25. Designed with an active surface for pointing and focusing, its enormous dish antenna is constructed with 4,450 individual triangular-shaped panels. The 500 meter physical diameter of the dish makes FAST the largest filled, single dish radio telescope on planet Earth. FAST will explore the Universe at radio frequencies, detecting emission from hydrogen gas in the Milky Way and distant galaxies, finding faint galactic and extragalactic pulsars, and searching for potential radio signals from extraterrestrials. via NASA http://ift.tt/2dckAvs

Saturn from Above

This image of Saturn could not have been taken from Earth. No Earth based picture could possibly view the night side of Saturn and the corresponding shadow cast across Saturn's rings. Since Earth is much closer to the Sun than Saturn, only the day side of the ringed planet is visible from the Earth. In fact, this image mosaic was taken earlier this year by the robotic Cassini spacecraft now orbiting Saturn, just before filming a 44-hour video of Saturn rotating. The beautiful rings of Saturn are seen in full expanse, while cloud details are visible including the polar hexagon surrounding the north pole. The Cassini mission is now in its final year as the spacecraft is scheduled to be programmed to dive into Saturn's atmosphere next September. via NASA http://ift.tt/2cu6CBa