• The Galactic Center in Radio from MeerKAT

    What’s happening at the center of our galaxy? It’s hard to tell with optical telescopes since visible light is blocked by intervening interstellar dust. In other bands of light, though, such as radio, the galactic center can be imaged and shows itself to be quite an interesting and active place. The featured picture shows the inaugural image of the MeerKAT array of 64 radio dishes just completed in South Africa. Spanning four times the angular size of the Moon (2 degrees), the image is impressively vast, deep, and detailed. Many known sources are shown in clear detail, including many with a prefix of Sgr, since the Galactic Center is in the direction of the constellation Sagittarius. In our Galaxy’s Center lies Sgr A, found here just to the right of the image center, which houses the Milky Way’s central supermassive black hole. Other sources in the image are not as well understood, including the Arc, just to the left of Sgr A, and numerous filamentary threads. Goals for MeerKAT include searching for radio emission from neutral hydrogen emitted in a much younger universe and brief but distant radio flashes.

  • Crescent Saturn

    Saturn never shows a crescent phase — from Earth. But when viewed from beyond, the majestic giant planet can show an unfamiliar diminutive sliver. This image of crescent Saturn in natural color was taken by the robotic Cassini spacecraft in 2007. The featured image captures Saturn’s majestic rings from the side of the ring plane opposite the Sun — the unilluminated side — another vista not visible from Earth. Pictured are many of Saturn’s photogenic wonders, including the subtle colors of cloud bands, the complex shadows of the rings on the planet, and the shadow of the planet on the rings. A careful eye will find the moons Mimas (2 o’clock) and Janus (4 o’clock), but the real challenge is to find Pandora (8 o’clock). Saturn is now nearly opposite from the Sun in the Earth’s sky and so can be seen in the evening starting just after sunset for the rest of the night.

  • 8 Minute and 30 Second Eclipse

    The total phase of the July 2nd solar eclipse lasted about 4 minutes and 30 seconds at the point of maximum eclipse. On the surface of planet Earth, that was about 600 nautical miles north of Easter Island in the Southern Pacific Ocean. But from 37,000 feet above, on a charter flight intercepting the Moon’s shadow, the Moon could be seen to completely block the Sun for about 8 minutes and 30 seconds. With a tailwind at the mid-eclipse intercept point, the plane was traveling around 488 nautical miles per hour chasing along the Moon’s shadow track. From above the clouds this wide-field image of the totally eclipsed Sun and shimmering solar corona over the wing records the spectacular view from a window seat on the sunward side of the aircraft.

  • La Silla Eclipse Sequence

    The road to the high mountaintop La Silla Observatory in the Chilean Atacama Desert also led in to the path of July 2nd’s total solar eclipse. Recorded at regular intervals before and after the total eclipse phase, the frames in this composite sequence include the moment the Moon’s dark shadow fell across some of planet Earth’s advanced large telescopes. The dreamlike view looks west toward the setting Sun and the approaching Moon shadow. In fact La Silla was a little north of the shadow track’s center line, so the region’s stunning, clear skies are slightly brighter to the north (right) in the scene.

  • In the Shadow of the Moon

    On July 2 denizens of planet Earth could stand in the Moon’s dark umbral shadow during South America’s 2019 total solar eclipse. It first touched down in the Southern Pacific Ocean, east of New Zealand. Racing toward the east along a narrow track, the shadow of the Moon made landfall along the Chilean coast with the Sun low on the western horizon. Captured in the foreground here are long shadows still cast by direct sunlight though, in the final moments before totality began. While diffraction spikes are from the camera lens aperture, the almost totally eclipsed Sun briefly shone like a beautiful diamond ring in the clear, darkened sky.

  • Robotic Dragonfly Selected to Fly Across Titan

    If you could fly across Titan, what would you see? To find out and to better explore this exotic moon of Saturn, NASA recently green-lighted Dragonfly, a mission to Titan with plans to deploy a helicopter-like drone. Saturn’s moon Titan is one of the largest moons in the Solar System and the only moon known to have a thick atmosphere and changing hydrocarbon lakes. After development, building, testing, and launch, Dragonfly is currently scheduled to reach Titan in 2034. The featured animated video envisions Dragonfly arriving at Titan, beginning its airborne exploration, landing to establishing a radio link back to Earth, and then continuing on to another trans-Titanian flight. It is hoped that Dragonfly will not only help humanity better understanding Titan’s weather, chemistry, and changing landscape, but also bolster humanity’s understanding of how life first developed on our young Earth. Astrophysicists: Browse 1,900+ codes in the Astrophysics Source Code Library

  • NGC 1566: The Spanish Dancer Spiral Galaxy

    If not perfect, then this spiral galaxy is at least one of the most photogenic. An island universe containing billions of stars and situated about 40 million light-years away toward the constellation of the Dolphinfish (Dorado), NGC 1566 presents a gorgeous face-on view. Classified as a grand design spiral, NGC 1566’s shows two prominent and graceful spiral arms that are traced by bright blue star clusters and dark cosmic dust lanes. Numerous Hubble Space Telescope images of NGC 1566 have been taken to study star formation, supernovas, and the spiral’s unusually active center. Some of these images, stored online in the Hubble Legacy Archive, were freely downloaded, combined, and digitally processed by an industrious amateur to create the featured image. NGC 1566’s flaring center makes the spiral one of the closest and brightest Seyfert galaxies, likely housing a central supermassive black hole wreaking havoc on surrounding stars and gas. Today: Total solar eclipse visible in parts of South America

  • The Big Corona

    Most photographs don’t adequately portray the magnificence of the Sun’s corona. Seeing the corona first-hand during a total solar eclipse is unparalleled. The human eye can adapt to see coronal features and extent that average cameras usually cannot. Welcome, however, to the digital age. The featured central image digitally combined short and long exposures that were processed to highlight faint and extended features in the corona of the total solar eclipse that occurred in August of 2017. Clearly visible are intricate layers and glowing caustics of an ever changing mixture of hot gas and magnetic fields in the Sun’s corona. Looping prominences appear bright pink just past the Sun’s limb. Faint details on the night side of the New Moon can even be made out, illuminated by sunlight reflected from the dayside of the Full Earth. Images taken seconds before and after the total eclipse show glimpses of the background Sun known as Baily’s Beads and Diamond Ring. Tomorrow, a new total solar eclipse will be visible from parts of South America.

  • Virtual Flight over Asteroid Vesta

    What would it be like to fly over the asteroid Vesta? Animators from the German Aerospace Center took actual images and height data from NASA’s Dawn mission when it visited asteroid Vesta a few years ago and generated a virtual movie. The featured video begins with a sequence above Divalia Fossa, an unusual pair of troughs running parallel over heavily cratered terrain. Next, the virtual spaceship explores Vesta’s 60-km Marcia Crater, showing numerous vivid details. Last, Dawn images were digitally recast with exaggerated height to better reveal Vesta’s 5-km high mountain Aricia Tholus. The second largest object in the Solar System’s asteroid belt, Vesta is the brightest asteroid visible from Earth and can be found with binoculars. Using Vesta Trek, you can explore all over Vesta yourself. Every June 30: Today is Asteroid Day

  • M83: The Thousand-Ruby Galaxx

    Big, bright, and beautiful, spiral galaxy M83 lies a mere twelve million light-years away, near the southeastern tip of the very long constellation Hydra. Prominent spiral arms traced by dark dust lanes and blue star clusters lend this galaxy its popular name, The Southern Pinwheel. But reddish star forming regions that dot the sweeping arms highlighted in this sparkling color composite also suggest another nickname, The Thousand-Ruby Galaxy. About 40,000 light-years across, M83 is a member of a group of galaxies that includes active galaxy Centaurus A. In fact, the core of M83 itself is bright at x-ray energies, showing a high concentration of neutron stars and black holes left from an intense burst of star formation. This sharp composite color image also features spiky foreground Milky Way stars and distant background galaxies. The image data was taken from the Subaru Telescope, the European Southern Observatory’s Wide Field Imager camera, and the Hubble Legacy Archive.

  • A Solstice Night in Paris

    The night of June 21 was the shortest night for planet Earth’s northern latitudes, so at latitude 48.9 degrees north, Paris was no exception. Still, the City of Light had an exceptionally luminous evening. Its skies were flooded with silvery night shining or noctilucent clouds after the solstice sunset. Hovering at the edge of space, the icy condensations on meteoric dust or volcanic ash are still in full sunlight at the extreme altitudes of the mesophere. Seen at high latitudes in summer months, stunning, wide spread displays of northern noctilucent clouds are now being reported.

  • The Longer Days

    This persistent six month long exposure compresses the time from solstice to solstice (December 21, 2018 to June 16, 2019) into a single point of view. Dubbed a solargraph, the unconventional picture was recorded with a tall, tube-shaped pinhole camera using a piece of photographic paper. Fixed to a single spot at Casarano, Italy for the entire exposure, the simple camera continuously records the Sun’s daily path as a glowing trail burned into the photosensitive paper. Breaks and gaps in the trails are caused by cloud cover. At the end of the exposure, the paper was scanned to create the digital image. Of course, starting in December the Sun trails peak lower in the sky, near the northern hemisphere’s winter solstice. The trails trails climb higher as the days grow longer and the June 21st summer solstice approaches.

  • Noctilucent Clouds, Reflections, and Silhouettes

    Sometimes it’s night on the ground but day in the air. As the Earth rotates to eclipse the Sun, sunset rises up from the ground. Therefore, at sunset on the ground, sunlight still shines on clouds above. Under usual circumstances, a pretty sunset might be visible, but unusual noctilucent clouds float so high up they can be seen well after dark. Normally too dim to be seen, they may become visible just after sunset during the summer when illuminated by sunlight from below. Noctilucent clouds are the highest clouds known and thought to be part of polar mesospheric clouds. Featured here as they appeared two weeks ago, a network of noctilucent clouds was captured not only in the distant sky but in reflection from a small lake just north of Zwolle, Netherlands, with trees in stark silhouette across the horizon. Unusually bright noctilucent clouds continue to appear over much of northern Europe. Much about noctilucent clouds has been discovered only over the past decade, while how they form and evolve remains a topic of active research. Gallery: Recent noctilucent clouds over Europe

  • 25 Brightest Stars in the Night Sky

    Do you know the names of some of the brightest stars? It’s likely that you do, even though some bright stars have names so old they date back to near the beginning of written language. Many world cultures have their own names for the brightest stars, and it is culturally and historically important to remember them. In the interest of clear global communication, however, the International Astronomical Union (IAU) has begun to designate standardized star names. Featured above in true color are the 25 brightest stars in the night sky, currently as seen by humans, coupled with their IAU-recognized names. Some star names have interesting meanings, including Sirius (“the scorcher” in Latin), Vega (“falling” in Arabic), and Antares (“rival to Mars” in Greek). It’s also likely that other of these bright star names are not familiar to you, even though familiar Polaris is too dim to make this list.

  • Anticrepuscular Rays Converge Opposite the Sun

    Is there ever anything interesting to see in the direction opposite the Sun? Sometimes there is. Notable items include your own shadow, a shadow of the Moon during a total solar eclipse, a full moon — in eclipse if the alignment’s good enough, a full earth, planets at opposition, glints from planets, the gegenschein from interplanetary dust, the center of a rainbow, hall-of-mountain fogbows, an airplane glory, and something yet again different if your timing, clouds and Sun position are just right. This different effect starts with clouds near the Sun that are causing common crepuscular rays to stream though. In the featured rare image taken from an airplane in mid-April, these beams were caught converging 180 degrees around, on the opposite side of the sky from the Sun, where they are called anticrepuscular rays. Therefore, it may look like something bright is shining at the antisolar point near the image center, but actually it is reverse-shining because, from your direction, light is streaming in, not out.

  • Carina Nebula Panorama from Hubble

    How do violent stars affect their surroundings? To help find out, astronomers created a 48-frame high-resolution, controlled-color panorama of the center of the Carina Nebula, one of the largest star forming regions on the night sky. The featured image, taken in 2007, was the most detailed image of the Carina Nebula yet taken. Cataloged as NGC 3372, the Carina Nebula is home to streams of hot gas, pools of cool gas, knots of dark globules, and pillars of dense dusty interstellar matter. The Keyhole Nebula, visible left of center, houses several of the most massive stars known. These large and violent stars likely formed in dark globules and continually reshape the nebula with their energetic light, outflowing stellar winds, and ultimately by ending their lives in supernova explosions. Visible to the unaided eye, the entire Carina Nebula spans over 450 light years and lies about 8,500 light-years away toward the constellation of Ship’s Keel (Carina).

  • Ares 3 Landing Site: The Martian Revisited

    This close-up from the Mars Reconnaissance Orbiter’s HiRISE camera shows weathered craters and windblown deposits in southern Acidalia Planitia. A striking shade of blue in standard HiRISE image colors, to the human eye the area would probably look grey or a little reddish. But human eyes have not gazed across this terrain, unless you count the eyes of NASA astronauts in the scifi novel The Martian by Andy Weir. The novel chronicles the adventures of Mark Watney, an astronaut stranded at the fictional Mars mission Ares 3 landing site corresponding to the coordinates of this cropped HiRISE frame. For scale Watney’s 6-meter-diameter habitat at the site would be about 1/10th the diameter of the large crater. Of course, the Ares 3 landing coordinates are only about 800 kilometers north of the (real life) Carl Sagan Memorial Station, the 1997 Pathfinder landing site.

  • Sunset Analemma

    Today, the solstice is at 15:54 Universal Time, the Sun reaching the northernmost declination in its yearly journey through planet Earth’s sky. A June solstice marks the astronomical beginning of summer in the northern hemisphere and winter in the south. It also brings the north’s longest day, the longest period between sunrise and sunset. In fact the June solstice sun is near the top, at the most northern point in the analemma or figure 8 curve traced by the position of the Sun in this composite photo. The analemma was created (video) from images taken every 10 days at the same time from June 21, 2018 and June 7, 2019. The time was chosen to be the year’s earliest sunset near the December solstice, so the analemma’s lowest point just kisses the unobstructed sea horizon at the left. Sunsets arranged along the horizon toward the right (north) are centered on the sunset at the September equinox and end with sunset at the June solstice.

  • A View Toward M106

    Big, bright, beautiful spiral, Messier 106 dominates this cosmic vista. The nearly two degree wide telescopic field of view looks toward the well-trained constellation Canes Venatici, near the handle of the Big Dipper. Also known as NGC 4258, M106 is about 80,000 light-years across and 23.5 million light-years away, the largest member of the Canes II galaxy group. For a far away galaxy, the distance to M106 is well-known in part because it can be directly measured by tracking this galaxy’s remarkable maser, or microwave laser emission. Very rare but naturally occurring, the maser emission is produced by water molecules in molecular clouds orbiting its active galactic nucleus. Another prominent spiral galaxy on the scene, viewed nearly edge-on, is NGC 4217 below and right of M106. The distance to NGC 4217 is much less well-known, estimated to be about 60 million light-years.

  • Our Galaxy’s Magnetic Center

    What’s the magnetic field like in the center of our Milky Way Galaxy? To help find out, NASA’s SOFIA — an observatory flying in a modified 747 — imaged the central region with an instrument known as HAWC+. HAWC+ maps magnetism by observing polarized infrared light emitted by elongated dust grains rotating in alignment with the local magnetic field. Now at our Milky Way’s center is a supermassive black hole with a hobby of absorbing gas from stars it has recently destroyed. Our galaxy’s black hole, though, is relatively quiet compared to the absorption rate of the central black holes in active galaxies. The featured image gives a clue as to why — a surrounding magnetic field may either channel gas into the black hole — which lights up its exterior, or forces gas into an accretion-disk holding pattern, causing it to be less active — at least temporarily. Inspection of the featured image — appearing perhaps like a surreal mashup of impasto art and gravitational astrophysics — brings out this telling clue by detailing the magnetic field in and around a dusty ring surrounding Sagittarius A*, the black hole in our Milky Way’s center.

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