2017 August 16

Perseid by the Sea
Image Credit & Copyright: Tamas Ladanyi (TWAN)

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.

2017 August 17

NGC 2442: Galaxy in Volans
Image Credit & Copyright: Processing - Robert Gendler, Roberto Colombari
Data - Hubble Legacy Archive, European Southern Observatory

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.

2017 August 18

Perseids over the Pyrénées
Image Credit & Copyright: Jean-Francois Graffand

This mountain and night skyscape stretches across the French Pyrenees National Park on August 12, near the peak of the annual Perseid meteor shower. The multi-exposure panoramic view was composed from the Col d'Aubisque, a mountain pass, about an hour before the bright gibbous moon rose. Centered is a misty valley and lights from the region's Gourette ski station toward the south. Taken over the following hour, frames capturing some of the night's long bright perseid meteors were aligned against the backdrop of stars and Milky Way.

2017 August 19

Total Solar Eclipse of 1979
Image Credit & Copyright: Jimmy Westlake (Colorado Mountain College)

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.

2017 August 20

Time-Lapse: A Total Solar Eclipse
Video Credit & Copyright: Colin Legg

Have you ever experienced a total eclipse of the Sun? This time-lapse movie depicts such an eclipse in dramatic detail, seen from Australia in 2012. As the video begins, a slight dimming of the Sun and the surrounding Earth is barely perceptible. As the Moon moves to cover nearly the entire Sun, darkness sweeps in from the left -- the fully blocked part of the Sun. At totality, only the bright solar corona extends past the edges of the Moon, and darkness surrounds you. Distant horizons are still bright, though, as they are not in the darkest part of the shadow. At mid-totality the darkness dips to the horizon below the eclipsed Sun, created by the shadow cone -- a corridor of shadow that traces back to the Moon. As the total solar eclipse ends -- usually after a few minutes -- the process reverses and Moon's shadow moves off to the other side. Tomorrow afternoon's total solar eclipse -- visible as at least a partial eclipse over all of North America -- can be experienced at social gatherings, some of which are being organized by local libraries.

2017 August 22

A Total Solar Eclipse over Wyoming
Image Credit & Copyright: Ben Cooper

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.

2017 August 23

The Crown of the Sun
Image Credit & Copyright: Derek Demeter (Emil Buehler Planetarium)

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.

2017 August 24

The Eagle and The Swan
Image Credit & Copyright: Josep Drudis

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.

2017 August 25

Diamond Ring in a Cloudy Sky
Image Credit & Copyright: Ashley Marando

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.

2017 August 26

Hurricane Harvey Strengthens
Video Credit: NASA-NOAA GOES Project

A large and dangerous hurricane has developed in the Gulf of Mexico. The featured time-lapse video shows Hurricane Harvey growing to Category 4 strength over the past few days, as captured by NASA and NOAA's GOES-East satellite. Starting as a slight dip in air pressure, hurricanes swell into expansive spiraling storm systems, complete with high winds and driving rain. Hurricanes are powered by evaporating ocean water, and so typically gain strength over warm water and lose strength over land. Much remains unknown about hurricanes and cyclones, including details of how they are formed and the exact path they will take. Hurricane Harvey, accompanied by a dangerous storm surge, made landfall late yesterday in Texas.

2017 August 27

The Heart Nebula in Hydrogen, Oxygen, and Sulfur
Image Credit & Copyright: Peter Jenkins

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 .

2017 August 28

A Fleeting Double Eclipse of the Sun
Image Credit & Copyright: Simon Tang

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 from Huron, California in a specific color emitted by hydrogen which highlights the Sun's chromosphere, a layer hotter and higher up than the usually photographed photosphere.

2017 August 29

Saturn in Blue and Gold
Image Credit: Cassini Imaging Team, SSI, JPL, ESA, NASA

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.

2017 August 30

Panoramic Eclipse Composite with Star Trails
Image Credit & Copyright: Stephane Vetter (Nuits sacrees, TWAN)

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.

2017 August 31

Lunar View, Solar Eclipse
Image Credit: NASA / GSFC / Arizona State Univ. / Lunar Reconnaissance Orbiter

Swinging around the lunar nearside on August 21, the Lunar Reconnaissance Orbiter turned to look back on a bright, Full Earth. As anticipated its Narrow Angle Camera scanned this sharp view of our fair planet, catching the shadow of the Moon racing along a path across the United States at about 1,500 miles per hour. In fact, the dark lunar shadow is centered over Hopkinsville, Kentucky at 1:25:30pm Central Daylight Time. From there, the New Moon blocked the Sun high in clear skies for about 2 minutes and 40 seconds in a total solar eclipse.

2017 September 1

A First Glimpse of the Great American Eclipse
Image Credit & Copyright: Babak Tafreshi (TWAN), National Geographic

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 eastern horizon giving way to a clear, pitch-black, stratospheric sky in the shadow of the Moon.

2017 September 2

Milky Way Voyager
Poster Illustration Credit: NASA, JPL-Caltech, Voyager

Launched in 1977 on a tour of the outer planets of the Solar System, Voyager 1 and 2 have become the longest operating and most distant spacecraft from Earth. Nearly 16 light-hours from the Sun, Voyager 2 has reached the edge of the heliosphere, the realm defined by the influence of the solar wind and the Sun's magnetic field. Now humanity's first ambassador to the Milky Way, Voyager 1 is over 19 light-hours away, beyond the heliosphere in interstellar space. Celebrate the Voyagers' 40 year journey toward the stars with NASA on September 5.

2017 September 3

A Waterspout in Florida
Image Credit & Copyright: Joey Mole

What's happening over the water? Pictured here is one of the better images yet recorded of a waterspout, a type of tornado that occurs over water. Waterspouts are spinning columns of rising moist air that typically form over warm water. Waterspouts can be as dangerous as tornadoes and can feature wind speeds over 200 kilometers per hour. Some waterspouts form away from thunderstorms and even during relatively fair weather. Waterspouts may be relatively transparent and initially visible only by an unusual pattern they create on the water. The featured image was taken in 2013 July near Tampa Bay, Florida. The Atlantic Ocean off the coast of Florida is arguably the most active area in the world for waterspouts, with hundreds forming each year. Some people speculate that waterspouts are responsible for some of the losses recorded in the Bermuda Triangle.

2017 September 4

Saturn's Rings from the Inside Out
Video Credit: NASA, JPL-Caltech, Space Science Institute

What do Saturn's rings look like from Saturn? Images from the robotic spacecraft Cassini are providing humanity with this unprecedented vantage point as it nears the completion of its mission. Previous to Cassini's Grand Finale orbits, all images of Saturn's majestic ring system were taken from outside of the rings looking in. Pictured in the inset is the remarkable video, while the spacecraft's positions are depicted in the surrounding animation. Details of the complex rings are evident as the short time-lapse sequence begins, while the paper-thin thickness of the rings becomes apparent near the video's end. The featured images were taken on August 20. Cassini has only a few more orbits around Saturn left before it is directed to dive into the giant planet on September 15.