August 31, 2017

A First Glimpse of the Great American Eclipse

Making landfall in Oregon, the Moon's dark umbral shadow toured the United States on August 21. Those gathered along its coast to coast path were witness to a total eclipse of the Sun, possibly the most widely shared celestial event in history. But first, the Moon's shadow touched the northern Pacific and raced eastward toward land. This dramatic snapshot was taken while crossing the shadow path 250 miles off the Oregon coast, 45,000 feet above the cloudy northern Pacific. Though from a shorter totality, it captures the eclipse before it could be seen from the US mainland. With the eclipsed Sun not far above, beautiful colors appear along the western horizon giving way to a clear, pitch-black, stratospheric sky in the shadow of the Moon. via NASA

August 29, 2017

Panoramic Eclipse Composite with Star Trails

What was happening in the sky during last week's total solar eclipse? This featured little-planet, all-sky, double time-lapse, digitally-fused composite captured celestial action during both night and day from a single location. In this 360x180 panorama, north and south are at the image bottom and top, while east and west are at the left and right edges, respectively. During four hours the night before the eclipse, star trails were captured circling the north celestial pole (bottom) as the Earth spun. During the day of the total eclipse, the Sun was captured every fifteen minutes from sunrise to sunset (top), sometimes in partial eclipse. All of these images were then digitally merged onto a single image taken exactly during the total solar eclipse. Then, the Sun's bright corona could be seen flaring around the dark new Moon (upper left), while Venus simultaneously became easily visible (top). The tree in the middle, below the camera, is a Douglas fir. The images were taken with care and planning at Magone Lake in Oregon, USA. via NASA

August 28, 2017

Saturn in Blue and Gold

Why is Saturn partly blue? The featured picture of Saturn approximates what a human would see if hovering close to the giant ringed world. The image was taken in 2006 March by the robot Cassini spacecraft now orbiting Saturn. Here Saturn's majestic rings appear directly only as a thin vertical line. The rings show their complex structure in the dark shadows they create on the image left. Saturn's fountain moon Enceladus, only about 500 kilometers across, is seen as the bump in the plane of the rings. The northern hemisphere of Saturn can appear partly blue for the same reason that Earth's skies can appear blue -- molecules in the cloudless portions of both planet's atmospheres are better at scattering blue light than red. When looking deep into Saturn's clouds, however, the natural gold hue of Saturn's clouds becomes dominant. It is not known why southern Saturn does not show the same blue hue -- one hypothesis holds that clouds are higher there. It is also not known why Saturn's clouds are colored gold. Next month, Cassini will end its mission with a final dramatic dive into Saturn's atmosphere. via NASA

August 27, 2017

A Fleeting Double Eclipse of the Sun

Last week, for a fraction of a second, the Sun was eclipsed twice. One week ago today, many people in North America were treated to a standard, single, partial solar eclipse. Fewer people, all congregated along a narrow path, experienced the eerie daytime darkness of a total solar eclipse. A dedicated few with fast enough camera equipment, however, were able to capture a double eclipse -- a simultaneous partial eclipse of the Sun by both the Moon and the International Space Station (ISS). The Earth-orbiting ISS crossed the Sun in less than a second, but to keep the ISS from appearing blurry, exposure times must be less than 1/1000th of a second. The featured image composite captured the ISS multiple times in succession as it zipped across the face of the Sun. The picture was taken in a specific color emitted by hydrogen which highlights the Sun's chromosphere, a layer hotter and higher up than the usually photographed photosphere. via NASA

August 26, 2017

The Heart Nebula in Hydrogen, Oxygen, and Sulfur

What powers the Heart Nebula? The large emission nebula dubbed IC 1805 looks, in whole, like a heart. The nebula's glow -- as well as the shape of the gas and dust clouds -- is powered by by stellar winds and radiation from massive hot stars in the nebula's newborn star cluster Melotte 15. This deep telescopic image maps the pervasive light of narrow emission lines from atoms of hydrogen, oxygen, and sulfur in the nebula. The field of view spans just over two degrees on the sky, so that it appears larger than four times the diameter of a full moon. The cosmic heart is found in the constellation of Cassiopeia, the boastful mythical Queen of Aethiopia . via NASA

August 24, 2017

Diamond Ring in a Cloudy Sky

As the Moon's shadow swept across the US on August 21, eclipse chasers in the narrow path of totality were treated to a diamond ring in the sky. At the beginning and end of totality, the fleeting and beautiful effect often produces audible gasps from an amazed audience. It occurs just before or after the appearance of the faint solar corona with a brief ring of light and glimpse of Sun. In this scene from the end of totality at Central, South Carolina, clouds drift near the Sun's diamond ring in the sky. via NASA

August 23, 2017

The Eagle and The Swan

The Eagle Nebula and the Swan Nebula span this broad starscape, a telescopic view toward the Sagittarius spiral arm and the center of our Milky Way galaxy. The Eagle, also known as M16, is at top and M17, the Swan, at bottom of the frame showing the cosmic clouds as brighter regions of active star-formation. They lie along the spiral arm suffused with reddish emission charactistic of atomic hydrogen gas, and dusty dark nebulae. M17, also called the Omega Nebula, is about 5500 light-years away, while M16 is some 6500 light-years distant. The center of both nebulae are locations of well-known close-up images of star formation from the Hubble Space Telescope. In this mosaic image that extends about 3 degrees across the sky, narrowband, high-resultion image data has been used to enhance the central regions of the Eagle and Swan. The extended wings of the Eagle Nebula spread almost 120 light-years. The Swan is over 30 light-years across. via NASA

August 22, 2017

The Crown of the Sun

During a total solar eclipse, the Sun's extensive outer atmosphere, or corona, is an inspirational sight. Streamers and shimmering features visible to the eye span a brightness range of over 10,000 to 1, making them notoriously difficult to capture in a single photograph. But this composite of telescopic images covers a wide range of exposure times to reveal the crown of the Sun in all its glory. The aligned and stacked digital frames were taken in clear skies above Stanley, Idaho in the Sawtooth Mountains during the Sun's total eclipse on August 21. A pinkish solar prominence extends just beyond the right edge of the solar disk. Even small details on the dark night side of the New Moon can be made out, illuminated by sunlight reflected from a Full Earth. via NASA

August 21, 2017

A Total Solar Eclipse over Wyoming

Will the sky be clear enough to see the eclipse? This question was on the minds of many people attempting to view yesterday's solar eclipse. The path of total darkness crossed the mainland of the USA from coast to coast, from Oregon to South Carolina -- but a partial eclipse occurred above all of North America. Unfortunately, many locations saw predominantly clouds. One location that did not was a bank of Green River Lake, Wyoming. There, clouds blocked the Sun intermittantly up to one minute before totality. Parting clouds then moved far enough away to allow the center image of the featured composite sequence to be taken. This image shows the corona of the Sun extending out past the central dark Moon that blocks our familiar Sun. The surrounding images show the partial phases of the solar eclipse both before and after totality. via NASA

August 18, 2017

Total Solar Eclipse of 1979

From cold, clear skies over Riverton, Manitoba, Canada, planet Earth, the solar corona surrounds the silhouette of the New Moon in this telescopic snapshot of the total solar eclipse of February 26, 1979. Thirty eight years ago, it was the last total solar eclipse visible from the contiguous United States. The narrow path of totality ran through the northwestern states of Washington, Oregon, Idaho, Montana, and North Dakota before crossing into Canadian provinces Saskatchewan, Manitoba, Ontario and Quebec. Following the upcoming August 21, 2017 total solar eclipse crossing the U.S. from coast to coast, an annular solar eclipse will be seen in the continental United States on October 14, 2023, visible along a route from Northern California to Florida. Then, the next total solar eclipse to touch the continental U.S. will track across 13 states from from Texas to Maine on April 8, 2024. via NASA

August 16, 2017

NGC 2442: Galaxy in Volans

Distorted galaxy NGC 2442 can be found in the southern constellation of the flying fish, (Piscis) Volans. Located about 50 million light-years away, the galaxy's two spiral arms extending from a pronounced central bar have a hook-like appearance in wide-field images. But this mosaicked close-up, constructed from Hubble Space Telescope and European Southern Observatory data, follows the galaxy's structure in amazing detail. Obscuring dust lanes, young blue star clusters and reddish star forming regions surround a core of yellowish light from an older population of stars. The sharp image data also reveal more distant background galaxies seen right through NGC 2442's star clusters and nebulae. The image spans about 75,000 light-years at the estimated distance of NGC 2442. via NASA

August 15, 2017

Perseid by the Sea

Just after moonrise on August 12 this grain of cosmic sand fell by the sea, its momentary flash part of the annual Perseid Meteor Shower. To create the Perseid meteors, dust along the orbit of periodic comet Swift-Tuttle is swept up by planet Earth. The cometary debris plows through the atmosphere at nearly 60 kilometers per second and is quickly vaporized at altitudes of 100 kilometers or so. Perseid meteors are often bright and colorful, like the one captured in this sea and night skyscape. Against starry sky and faint Milky Way the serene view looks south and west across the Adriatic Sea, from the moonlit Dalmatian coast toward the island of Brac. via NASA

August 14, 2017

Stars, Gas, and Dust Battle in the Carina Nebula

Chaos reigns in the Carina Nebula where massive stars form and die. Striking and detailed, this close-up of a portion of the famous nebula is a combination of light emitted by hydrogen (shown in red) and oxygen (shown in blue). Dramatic dark dust knots and complex features revealed are sculpted by the winds and radiation of Carina's massive and energetic stars. One iconic feature of the Carina Nebula is the dark V-shaped dust lane that occurs in the top half of the image. The Carina Nebula spans about 200 light years, lies about 7,500 light years distant, and is visible with binoculars toward the southern constellation of Carina. In a billion years after the dust settles -- or is destroyed, and the gas dissipates -- or gravitationally condenses, then only the stars will remain -- but not even the brightest ones. via NASA

August 12, 2017

Detailed View of a Solar Eclipse Corona

Only in the fleeting darkness of a total solar eclipse is the light of the solar corona easily visible. Normally overwhelmed by the bright solar disk, the expansive corona, the sun's outer atmosphere, is an alluring sight. But the subtle details and extreme ranges in the corona's brightness, although discernible to the eye, are notoriously difficult to photograph. Pictured here, however, using multiple images and digital processing, is a detailed image of the Sun's corona taken during the 2008 August total solar eclipse from Mongolia. Clearly visible are intricate layers and glowing caustics of an ever changing mixture of hot gas and magnetic fields. Bright looping prominences appear pink just above the Sun's limb. A similar solar corona might be visible through clear skies in a thin swath across the USA during a total solar eclipse that occurs just one week from tomorrow. via NASA

August 10, 2017

A Total Solar Eclipse of Saros 145

A darkened sky holds bright planet Venus, the New Moon in silhouette, and the shimmering corona of the Sun in this image of a total solar eclipse. A composite of simultaneous telephoto and wide angle frames it was taken in the path of totality 18 years ago, August 11, 1999, near Kastamonu, Turkey. That particular solar eclipse is a member of Saros 145. Known historically from observations of the Moon's orbit, the Saros cycle predicts when the Sun, Earth, and Moon will return to the same geometry for a solar (or lunar) eclipse. The Saros has a period of 18 years, 11 and 1/3 days. Eclipses separated by one Saros period belong to the same numbered Saros series and are very similar. But the path of totality for consecutive solar eclipses in the same Saros shifts across the Earth because the planet rotates for an additional 8 hours during the cycle's fractional day. So the next solar eclipse of Saros 145 will also be a total eclipse, and the narrow path of totality will track coast to coast across the United States on August 21, 2017. via NASA

August 9, 2017

Night of the Perseids

This weekend, meteors will rain down near the peak of the annual Perseid Meteor Shower. Normally bright and colorful, the Perseid shower meteors are produced by dust swept up by planet Earth from the orbit of Comet Swift-Tuttle. They streak from a radiant in Perseus, above the horizon in clear predawn skies. Despite interfering light from August's waning gibbous moon, this year's Perseids will still be enjoyable, especially if you can find yourself in an open space, away from city lights, and in good company. Frames used in this composite view capture bright Perseid meteors from the 2016 meteor shower set against a starry background along the Milky Way, with even the faint Andromeda Galaxy just above center. In the foreground, astronomers of all ages have gathered on a hill above the Slovakian village of Vrchtepla. via NASA

August 8, 2017

August Lunar Eclipse

August's Full Moon is framed in this sharp, high dynamic range composition. Captured before sunrise on August 8 from Sydney, Australia, south is up and the Earth's dark, umbral shadow is at the left, near the maximum phase of a partial lunar eclipse. Kicking off the eclipse season, this time the Full Moon's grazing slide through Earth's shadow was visible from the eastern hemisphere. Up next is the much anticipated total solar eclipse of August 21. Then, the New Moon's shadow track will include North America, the narrow path of totality running coast to coast through the United States. via NASA

August 7, 2017

Density Waves in Saturns Rings from Cassini

What causes the patterns in Saturn's rings? The Cassini spacecraft, soon ending its 13 years orbiting Saturn, has sent back another spectacular image of Saturn's immense ring system in unprecedented detail. The physical cause for some of Saturn's ring structures is not always understood. The cause for the beautifully geometric type of ring structure shown here in ring of Saturn, however, is surely a density wave. A small moon systematically perturbing the orbits of ring particles circling Saturn at slightly different distances causes such a density wave bunching. Also visible on the lower right of the image is a bending wave, a vertical wave in ring particles also caused by the gravity of a nearby moon. Cassini's final orbits are allowing a series of novel scientific measurements and images of the Solar System's most grand ring system. via NASA

August 6, 2017

Spiral Galaxy NGC 1512: The Inner Ring

Most galaxies don't have any rings -- why does this galaxy have two? To begin, the bright band near NGC 1512's center is a nuclear ring, a ring that surrounds the galaxy center and glows brightly with recently formed stars. Most stars and accompanying gas and dust, however, orbit the galactic center in a ring much further out -- here seen near the image edge. This ring is called, counter-intuitively, the inner ring. If you look closely, you will see this the inner ring connects ends of a diffuse central bar that runs horizontally across the galaxy. These ring structures are thought to be caused by NGC 1512's own asymmetries in a drawn-out process called secular evolution. The gravity of these galaxy asymmetries, including the bar of stars, cause gas and dust to fall from the inner ring to the nuclear ring, enhancing this ring's rate of star formation. Some spiral galaxies also have a third ring -- an outer ring that circles the galaxy even further out. via NASA

August 4, 2017

Gravity s Grin

Albert Einstein's general theory of relativity, published over 100 years ago, predicted the phenomenon of gravitational lensing. And that's what gives these distant galaxies such a whimsical appearance, seen through the looking glass of X-ray and optical image data from the Chandra and Hubble space telescopes. Nicknamed the Cheshire Cat galaxy group, the group's two large elliptical galaxies are suggestively framed by arcs. The arcs are optical images of distant background galaxies lensed by the foreground group's total distribution of gravitational mass. Of course, that gravitational mass is dominated by dark matter. The two large elliptical "eye" galaxies represent the brightest members of their own galaxy groups which are merging. Their relative collisional speed of nearly 1,350 kilometers/second heats gas to millions of degrees producing the X-ray glow shown in purple hues. Curiouser about galaxy group mergers? The Cheshire Cat group grins in the constellation Ursa Major, some 4.6 billion light-years away. via NASA

August 3, 2017

North North Temperate Zone Little Red Spot

On July 11, the Juno spacecraft once again swung near the turbulent Jovian cloud tops. On its seventh orbital closest approach this perijove passage brought Juno within 3,500 kilometers of the Solar System's largest planetary atmosphere. Near perijove the rotating JunoCam was able to record this stunning, clear view of one of Jupiter's signature vortices. About 8,000 kilometers in diameter, the anticyclonic storm system was spotted in Jupiter's North North Temperate Zone in the 1990s. That makes it about half the size of an older and better known Jovian anticyclone, the Great Red Spot, but only a little smaller than planet Earth. At times taking on reddish hues, the enormous storm system is fondly known as a North North Temperate Zone Little Red Spot. via NASA

August 2, 2017

Pelican Nebula Close Up

The prominent ridge of emission featured in this vivid skyscape is designated IC 5067. Part of a larger emission region with a distinctive shape, popularly called The Pelican Nebula, the ridge spans about 10 light-years and follows the curve of the cosmic pelican's head and neck. Fantastic, dark shapes inhabiting the view are clouds of cool gas and dust sculpted by energetic radiation from young, hot, massive stars. But stars are also forming within the dark shapes. Twin jets emerging from the tip of the long, dark tendril left of center are the telltale signs of an embedded protostar cataloged as Herbig-Haro 555 (HH 555). In fact, other Herbig-Haro objects indicating the presence of protostars are found within the frame. The Pelican Nebula itself, also known as IC 5070, is about 2,000 light-years away. To find it, look northeast of bright star Deneb in the high flying constellation Cygnus. via NASA

August 1, 2017

The Dust Monster in IC 1396

Is there a monster in IC 1396? Known to some as the Elephant's Trunk Nebula, parts of gas and dust clouds of this star formation region may appear to take on foreboding forms, some nearly human. The only real monster here, however, is a bright young star too far from Earth to hurt us. Energetic light from this star is eating away the dust of the dark cometary globule near the top of the featured image. Jets and winds of particles emitted from this star are also pushing away ambient gas and dust. Nearly 3,000 light-years distant, the relatively faint IC 1396 complex covers a much larger region on the sky than shown here, with an apparent width of more than 10 full moons. via NASA