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A different astronomy and space science related image is featured each day, along with a brief explanation.
Highest, Tallest, and Closest to the Stars
Fans of planet Earth probably recognize its highest mountain, the Himalayan Mount Everest, on the left in this 3-panel skyscape of The World at Night. Shrouded in cloud Everest's peak is at 8,848 meters (29,029 feet) elevation above sea level. In the middle panel, stars trail above volcanic Mauna Kea forming part of the island of Hawaii. Festooned with astronomical observatories, its summit lies a mere 4,168 meters above sea level. Still, measured from its base starting below the ocean's surface, Mauna Kea is over 10,000 meters tall, making it Earth's tallest mountain from base to summit. At right, beneath the arc of the Milky Way is the Andean mountain Chimborazo in Ecuador. The highest equatorial mountain, the Chimborazo volcano's peak elevation is 6,268 meters above sea level. But rotating planet Earth is a flattened sphere (oblate spheroid) in shape, its equatorial diameter greater than its diameter measured pole to pole. Sitting nearly on top of Earth's greatest equatorial bulge, Chimborazo's peak is the farthest point on the planet's surface from the center, over 2,000 meters farther from the center of the Earth than Everest's peak. That makes Chimborazo's summit the place on Earth's surface closest to the stars.
A Supernova through Galaxy Dust
Telescopes around the world are tracking a bright supernova that occurred in a nearby dusty galaxy. The powerful stellar explosion was first noted earlier this month. The nearby galaxy is the photogenic Centaurus A, visible with binoculars and known for impressive filaments of light-absorbing dust that cross its center. Cen A is featured here in a high-resolution archival Hubble Space Telescope image, with an inset image featuring the supernova taken from the ground only two days after discovery. Designated SN2016adj, the supernova is highlighted with crosshairs in the inset, appearing just to the left of a bright foreground star in our Milky Way Galaxy. This supernova is currently thought to be of Type IIb, a stellar-core-collapse supernova, and is of high interest because it occurred so nearby and because it is being seen through a known dust filament. Current and future observations of this supernova may give us new clues about the fates of massive stars and how some elements found on our Earth were formed.
Where Your Shadow Has Company
Want to take a relaxing interstellar vacation? Consider visiting Kepler-16b, a world in a binary star system. In fact Kepler-16b is the first discovered circumbinary planet. It was detected in a wide 229 day orbit around a close pair of cool, low-mass stars some 200 light-years away. The parent stars eclipse one another in their orbits, observed as a dimming of starlight. But Kepler-16b itself was discovered by following the additional very slight dimming produced during its transits. Like sci-fi planet Tatooine of Star Wars fame, two suns would set over its horizon. Still, Kepler 16b is probably not a Tatooine-like terrestrial desert world. Instead, Kepler 16b is thought to be a cold, uninhabitable planet with about the mass of Saturn and a gaseous surface ... so plan to dress accordingly. Or, choose another Visions of the Future vacation destination.
Hitomi Launches
On February 17 at 5:45pm JST this H-IIA rocket blasted skyward from JAXA's Tanegashima Space Center located off the southern coast of Japan, planet Earth. Onboard was the ASTRO-H X-ray astronomy satellite, now in orbit. Designed to explore the extreme cosmos from black holes to massive galaxy clusters, the satellite observatory is equipped with four cutting-edge X-ray telescopes and instruments sensitive to photon energies from 300 to 600,000 electron volts. By comparison, visible light photon energies are 2 to 3 electron volts. Following a tradition of renaming satellites after their successful launch, ASTRO-H has been newly dubbed "Hitomi", inspired by an ancient legend of dragons. Hitomi means "the pupil of the eye".
Star Forming Region S106
Massive star IRS 4 is beginning to spread its wings. Born only about 100,000 years ago, material streaming out from this newborn star has formed the nebula dubbed Sharpless 2-106 Nebula (S106), featured here. A large disk of dust and gas orbiting Infrared Source 4 (IRS 4), visible in brown near the image center, gives the nebula an hourglass or butterfly shape. S106 gas near IRS 4 acts as an emission nebula as it emits light after being ionized, while dust far from IRS 4 reflects light from the central star and so acts as a reflection nebula. Detailed inspection of a recent infrared image of S106 reveal hundreds of low-mass brown dwarf stars lurking in the nebula's gas. S106 spans about 2 light-years and lies about 2000 light-years away toward the constellation of the Swan (Cygnus).
A Heart Shaped Lenticular Cloud
Can a cloud love a mountain? Perhaps not, but on a Valentine's Day like today, one might be prone to seeing heart-shaped symbols where they don't actually exist. A fleeting pareidolia, the featured heart was really a lenticular cloud that appeared one morning last July above Mount Cook National Park in New Zealand. A companion video shows the lenticular cloud was mostly stationary in the sky but shifted and vibrated with surrounding winds. The cloud's red color was caused by the Sun rising off the frame to the right. Lenticular clouds are somewhat rare but can form in air that passes over a mountain. Then, vertical eddies may form where rising air cools past the dew point causing water carried by the air to condense into droplets. Unfortunately, this amazing sight made the fascinated videographer late for breakfast.
LIGO Detects Gravitational Waves from Merging Black Holes
Gravitational radiation has been directly detected. The first-ever detection was made by both facilities of the Laser Interferometer Gravitational-Wave Observatory (LIGO) in Washington and Louisiana simultaneously last September. After numerous consistency checks, the resulting 5-sigma discovery was published today. The measured gravitational waves match those expected from two large black holes merging after a death spiral in a distant galaxy, with the resulting new black hole momentarily vibrating in a rapid ringdown. A phenomenon predicted by Einstein, the historic discovery confirms a cornerstone of humanity's understanding of gravity and basic physics. It is also the most direct detection of black holes ever. The featured illustration depicts the two merging black holes with the signal strength of the two detectors over 0.3 seconds superimposed across the bottom. Expected future detections by Advanced LIGO and other gravitational wave detectors may not only confirm the spectacular nature of this measurement but hold tremendous promise of giving humanity a new way to see and explore our universe.
Light Pillars over Alaska
What's happening behind those houses? Pictured here are not auroras but nearby light pillars, a nearby phenomenon that can appear as a distant one. In most places on Earth, a lucky viewer can see a Sun-pillar, a column of light appearing to extend up from the Sun caused by flat fluttering ice-crystals reflecting sunlight from the upper atmosphere. Usually these ice crystals evaporate before reaching the ground. During freezing temperatures, however, flat fluttering ice crystals may form near the ground in a form of light snow, sometimes known as a crystal fog. These ice crystals may then reflect ground lights in columns not unlike a Sun-pillar. The featured image was taken in Fort Wainwright near Fairbanks in central Alaska.
Five Planets at Castell de Burriac
February's five planet line-up stretches across a clear sky in this predawn scene. A hilltop Castell de Burriac looms in the foreground, overlooking the town of Cabrera de Mar near Barcelona, Spain, planet Earth. The mosaicked, panoramic image looks south. It merges three different exposure times to record a bright Last Quarter Moon, planets, seaside city lights, and dark castle ruins. Seen on February 1st the Moon was near Mars on the sky. But this week early morning risers have watched it move on, passing near Saturn and finally Venus and Mercury, sliding along near the ecliptic toward the dawn, approaching the February 7 New Moon.
Dwarf Planet Ceres
Dwarf planet Ceres is the largest object in the Solar System's main asteroid belt, with a diameter of about 950 kilometers (590 miles). Ceres is seen here in approximately true color, based on image data from the Dawn spacecraft recorded on May 4, 2015. On that date, Dawn's orbit stood 13,642 kilometers above the surface of the small world. Two of Ceres' famous mysterious bright spots at Oxo crater and Haulani crater are near center and center right of this view. Casting a telltale shadow at the bottom is Ceres' cone-shaped, lonely mountain Ahuna Mons. Presently some 385 kilometers above the Cerean surface, the ion-propelled Dawn spacecraft is now returning images from its closest mapping orbit.
Comet 67P from Spacecraft Rosetta
Spacecraft Rosetta continues to circle and map Comet Churyumov-Gerasimenko. Crossing the inner Solar System for ten years to reach the vicinity of the comet in 2014, the robotic spacecraft continues to image the unusual double-lobed comet nucleus. The featured image, taken one year ago, shows dust and gas escaping from the comet's nucleus. Although appearing bright here, the comet's surface reflects only about four percent of impinging visible light, making it as dark as coal. Comet 67P/Churyumov–Gerasimenko spans about four kilometers in length and has a surface gravity so low that an astronaut could jump off of it. With Rosetta in tow, Comet 67P passed its closest to the Sun last year and is now headed back to the furthest point -- just past the orbit of Jupiter.
MWC 922: The Red Square Nebula
What could cause a nebula to appear square? No one is quite sure. The hot star system known as MWC 922, however, appears to be embedded in a nebula with just such a shape. The featured image combines infrared exposures from the Hale Telescope on Mt. Palomar in California, and the Keck-2 Telescope on Mauna Kea in Hawaii. A leading progenitor hypothesis for the square nebula is that the central star or stars somehow expelled cones of gas during a late developmental stage. For MWC 922, these cones happen to incorporate nearly right angles and be visible from the sides. Supporting evidence for the cone hypothesis includes radial spokes in the image that might run along the cone walls. Researchers speculate that the cones viewed from another angle would appear similar to the gigantic rings of supernova 1987A, possibly indicating that a star in MWC 922 might one day itself explode in a similar supernova.
Hidden Galaxy IC 342
Similar in size to large, bright spiral galaxies in our neighborhood, IC 342 is a mere 10 million light-years distant in the long-necked, northern constellation Camelopardalis. A sprawling island universe, IC 342 would otherwise be a prominent galaxy in our night sky, but it is hidden from clear view and only glimpsed through the veil of stars, gas and dust clouds along the plane of our own Milky Way galaxy. Even though IC 342's light is dimmed by intervening cosmic clouds, this deep telescopic image traces the galaxy's obscuring dust, blue star clusters, and glowing pink star forming regions along spiral arms that wind far from the galaxy's core. IC 342 may have undergone a recent burst of star formation activity and is close enough to have gravitationally influenced the evolution of the local group of galaxies and the Milky Way.
An Airglow Fan from Lake to Sky
Why would the sky look like a giant fan? Airglow. The featured intermittent green glow appeared to rise from a lake through the arch of our Milky Way Galaxy, as captured last summer next to Bryce Canyon in Utah, USA. The unusual pattern was created by atmospheric gravity waves, ripples of alternating air pressure that can grow with height as the air thins, in this case about 90 kilometers up. Unlike auroras powered by collisions with energetic charged particles and seen at high latitudes, airglow is due to chemiluminescence, the production of light in a chemical reaction. More typically seen near the horizon, airglow keeps the night sky from ever being completely dark.
Where Your Elements Came From
The hydrogen in your body, present in every molecule of water, came from the Big Bang. There are no other appreciable sources of hydrogen in the universe. The carbon in your body was made by nuclear fusion in the interior of stars, as was the oxygen. Much of the iron in your body was made during supernovas of stars that occurred long ago and far away. The gold in your jewelry was likely made from neutron stars during collisions that may have been visible as short-duration gamma-ray bursts. Elements like phosphorus and copper are present in our bodies in only small amounts but are essential to the functioning of all known life. The featured periodic table is color coded to indicate humanity's best guess as to the nuclear origin of all known elements. The sites of nuclear creation of some elements, such as copper, are not really well known and are continuing topics of observational and computational research.
USA's Northeast Megalopolis from Space
Can you identify a familiar area in the northeast USA just from nighttime lights? It might be possible because many major cities are visible, including (right to left) New York, Philadelphia, Baltimore, Washington, Richmond and Norfolk -- Boston of the USA's Northeast megalopolis is not pictured. The featured image was taken in 2012 from the International Space Station. In the foreground are two Russian cargo ships with prominent solar panels. This Northeast megalopolis of the USA contains almost 20 percent of the people of the USA but only about 2 percent of the land area. Also known also as the Northeast Corridor and part of the Eastern Seaboard, about 10 percent of the world's largest companies are headquartered here. The near continuity of the lights seem to add credence to the 1960s-era prediction that the entire stretch is evolving into one continuous city.
M82: Galaxy with a Supergalactic Wind
What's lighting up the Cigar Galaxy? M82, as this irregular galaxy is also known, was stirred up by a recent pass near large spiral galaxy M81. This doesn't fully explain the source of the red-glowing outwardly expanding gas, however. Evidence indicates that this gas is being driven out by the combined emerging particle winds of many stars, together creating a galactic superwind. The featured photographic mosaic highlights a specific color of red light strongly emitted by ionized hydrogen gas, showing detailed filaments of this gas. The filaments extend for over 10,000 light years. The 12-million light-year distant Cigar Galaxy is the brightest galaxy in the sky in infrared light, and can be seen in visible light with a small telescope towards the constellation of the Great Bear (Ursa Major).
NGC 2403 in Camelopardalis
Magnificent island universe NGC 2403 stands within the boundaries of the long-necked constellation Camelopardalis. Some 10 million light-years distant and about 50,000 light-years across, the spiral galaxy also seems to have more than its fair share of giant star forming HII regions, marked by the telltale reddish glow of atomic hydrogen gas. The giant HII regions are energized by clusters of hot, massive stars that explode as bright supernovae at the end of their short and furious lives. A member of the M81 group of galaxies, NGC 2403 closely resembles another galaxy with an abundance of star forming regions that lies within our own local galaxy group, M33 the Triangulum Galaxy. Spiky in appearance, bright stars in this colorful galaxy portrait of NGC 2403 are in the foreground, within our own Milky Way.
Milky Way over the Pinnacles in Australia
What strange world is this? Earth. In the foreground of the featured image are the Pinnacles, unusual rock spires in Nambung National Park in Western Australia. Made of ancient sea shells (limestone), how these human-sized picturesque spires formed remains unknown. In the background, just past the end of the central Pinnacle, is a bright crescent Moon. The eerie glow around the Moon is mostly zodiacal light, sunlight reflected by dust grains orbiting between the planets in the Solar System. Arching across the top is the central band of our Milky Way Galaxy. Many famous stars and nebula are also visible in the background night sky. The featured 29-panel panorama was taken and composed last September after detailed planning that involved the Moon, the rock spires, and their corresponding shadows. Even so, the strong zodiacal light was a pleasant surprise.
White Rock Fingers on Mars
What caused this unusual light rock formation on Mars? Intrigued by the possibility that they could be salt deposits left over as an ancient lakebed dried-up, detailed studies of these fingers now indicate a more mundane possibility: volcanic ash. Studying the exact color of the formation indicated the possible volcanic origin. The light material appears to have eroded away from surrounding area, indicating a very low-density substance. The stark contrast between the rocks and the surrounding sand is compounded by the unusual darkness of the sand. The featured picture was taken with the Thermal Emission Imaging System on the Mars Odyssey, the longest serving spacecraft currently orbiting Mars. The image spans about 10 kilometers inside a larger crater.
Yutu on a Little Planet
Tracks lead to a small robot perched near the top of this bright little planet. Of course, the planet is really the Moon. The robot is the desk-sized Yutu rover, leaving its looming Chang'e 3 lander after a after a mid-December 2013 touch down in the northern Mare Imbrium. The little planet projection is a digitally warped and stitched mosaic of images from the lander's terrain camera covering 360 by 180 degrees. Ultimately traveling over 100 meters, Yutu came to a halt in January 2014. The lander's instruments are still working though, after more than two years on the lunar surface. Meanwhile, an interactive panoramic version of this little planet is available here.
Galaxies in the River
Large galaxies grow by eating small ones. Even our own galaxy practices galactic cannibalism, absorbing small galaxies that get too close and are captured by the Milky Way's gravity. In fact, the practice is common in the universe and illustrated by this striking pair of interacting galaxies from the banks of the southern constellation Eridanus, The River. Located over 50 million light years away, the large, distorted spiral NGC 1532 is seen locked in a gravitational struggle with dwarf galaxy NGC 1531 (right of center), a struggle the smaller galaxy will eventually lose. Seen edge-on, spiral NGC 1532 spans about 100,000 light-years. Nicely detailed in this sharp image, the NGC 1532/1531 pair is thought to be similar to the well-studied system of face-on spiral and small companion known as M51.
Advanced LIGO: Gravitational Wave Detectors Upgraded
Accelerate a charge and you'll get electromagnetic radiation: light. But accelerate any mass and you'll get gravitational radiation. Light is seen all the time, but, so far, a confirmed direct detection of gravitational radiation has been elusive. When absorbed, gravitational waves create a tiny symmetric jiggle similar to squashing a rubber ball and letting go quickly. Separated detectors can be used to discern gravitational waves from everyday bumps. Powerful astronomical sources of gravitational radiation would coincidentally jiggle even detectors on opposite ends of the Earth. Pictured here are the four-kilometer-long arms of one such detector: the LIGO Hanford Observatory in Washington state, USA. Together with its sister interferometer in Louisiana, these gravitational wave detectors continue to be upgraded and are now more sensitive than ever.
Massive Stars in NGC 6357
Massive stars lie within NGC 6357, an expansive emission nebula complex some 6,500 light-years away toward the tail of the constellation Scorpius. In fact, positioned near center in this ground-based close-up of NGC 6357, star cluster Pismis 24 includes some of the most massive stars known in the galaxy, stars with nearly 100 times the mass of the Sun. The nebula's bright central region also contains dusty pillars of molecular gas, likely hiding massive protostars from the prying eyes of optical instruments. Intricate shapes in the nebula are carved as interstellar winds and energetic radiation from the young and newly forming massive stars clear out the natal gas and dust and power the nebular glow. Enhancing the nebula's cavernous appearance, narrowband image data was included in this composite color image in a Hubble palette scheme. Emission from sulfur, hydrogen, and oxygen atoms is shown in red green and blue hues. The alluring telescopic view spans about 50 light-years at the estimated distance of NGC 6357.
Galaxy Wars: M81 versus M82
In the lower left corner, surrounded by blue spiral arms, is spiral galaxy M81. In the upper right corner, marked by red gas and dust clouds, is irregular galaxy M82. This stunning vista shows these two mammoth galaxies locked in gravitational combat, as they have been for the past billion years. The gravity from each galaxy dramatically affects the other during each hundred million-year pass. Last go-round, M82's gravity likely raised density waves rippling around M81, resulting in the richness of M81's spiral arms. But M81 left M82 with violent star forming regions and colliding gas clouds so energetic the galaxy glows in X-rays. This big battle is seen from Earth through the faint glow of an Integrated Flux Nebula, a little studied complex of diffuse gas and dust clouds in our Milky Way Galaxy. In a few billion years only one galaxy will remain.
Find the Man in the Moon
Have you ever seen the Man on the Moon? This common question plays on the ability of humans to see pareidolia -- imagining familiar icons where they don't actually exist. The textured surface of Earth's full Moon is home to numerous identifications of iconic objects, not only in modern western culture but in world folklore throughout history. Examples, typically dependent on the Moon's perceived orientation, include the Woman in the Moon and the Rabbit in the Moon. One facial outline commonly identified as the Man in the Moon starts by imagining the two dark circular areas -- lunar maria -- here just above the Moon's center, to be the eyes. Surprisingly, there actually is a man in this Moon image -- a close look will reveal a real person -- with a telescope -- silhouetted against the Moon. This featured well-planned image was taken in mid-January in Cadalso de los Vidrios in Madrid, Spain. Do you have a favorite object that you see in the Moon?
A Five Planet Dawn
As January closes and in the coming days of February, early morning risers can spot the five naked-eye planets before dawn. Though some might claim to see six planets, in this seaside panoramic view all five celestial wanderers were found above the horizon along with a bright waning gibbous Moon on January 27. Nearly aligned along the plane of the ecliptic, but not along a line with the Sun, the five planets are spread well over 100 degrees across the sky. Just arriving on the predawn scene, fleeting Mercury stands above the southeastern horizon in the golden light of the approaching sunrise.
Elliptical M60, Spiral NGC 4647
Giant elliptical galaxy M60 and spiral galaxy NGC 4647 do look like an odd couple in this sharp cosmic portrait from the Hubble Space Telescope. But they are found in a region of space where galaxies tend to gather, on the eastern side of the nearby Virgo Galaxy Cluster. About 54 million light-years distant, bright M60's simpler egg-like shape is created by its randomly swarming older stars, while NGC 4647's young blue stars, gas and dust are organized into winding arms rotating in a flattened disk. Spiral NGC 4647 is estimated to be more distant than M60, some 63 million light-years away. Also known as Arp 116, the pair of galaxies may be on the verge of a significant gravitational encounter, though. M60 (aka NGC 4649) is about 120,000 light-years across. The smaller NGC 4647 spans around 90,000 light-years, about the size of our own Milky Way.
A Candidate for the Biggest Boom Yet Seen
It is a candidate for the brightest and most powerful explosion ever seen -- what is it? The flaring spot of light was found by the All Sky Automated Survey for Supernovae (ASASSN) in June of last year and labelled ASASSN-15lh. Located about three billion light years distant, the source appears tremendously bright for anything so far away: roughly 200 times brighter than an average supernova, and temporarily 20 times brighter than all of the stars in our Milky Way Galaxy combined. Were light emitted by ASASSN-15lh at this rate in all directions at once, it would be the most powerful explosion yet recorded. No known stellar object was thought to create an explosion this powerful, although pushing the theoretical limits for the spin-down of highly-magnetized neutron star -- a magnetar -- gets close. Assuming the flare fades as expected later this year, astronomers are planning to use telescopes including Hubble to zoom in on the region to gain more clues. The above-featured artist's illustration depicts a hypothetical night sky of a planet located across the host galaxy from the outburst.
Star Cluster R136 Bursts Out
In the center of star-forming region 30 Doradus lies a huge cluster containing some of the largest, hottest, and most massive stars known. These stars, known collectively as star cluster R136, were captured in the featured image in visible light by the Wide Field Camera 3 in 2009 peering through the Hubble Space Telescope. Gas and dust clouds in 30 Doradus, also known as the Tarantula Nebula, have been sculpted into elongated shapes by powerful winds and ultraviolet radiation from these hot cluster stars. The 30 Doradus Nebula lies within a neighboring galaxy known as the Large Magellanic Cloud and is located a mere 170,000 light-years away.
