The Brightness of the Sun

The bright Sun, a portion of the International Space Station and Earth's horizon are featured in this image photographed during the STS-134 mission's fourth spacewalk in May 2011. The image was taken using a fish-eye lens attached to an electronic still camera. 

Image Credit: NASA

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Churning Out Stars

W3 is an enormous stellar nursery about 6,200 light-years away in the Perseus Arm, one of the Milky Way galaxy’s main spiral arms, which hosts both low- and high-mass star formation. In this image from the Herschel space observatory, the low-mass forming stars are seen as tiny yellow dots embedded in cool red filaments, while the highest-mass stars - with greater than eight times the mass of our Sun - emit intense radiation, heating up the gas and dust around them and appearing here in blue. 

This three-color image of W3 combines Herschel bands at 70 microns (blue), 160 microns (green) and 250 microns (red). The image spans about 2 by 2 degrees. North is up and east is to the left. 

Image Credit: ESA/PACS & SPIRE consortia, A. Rivera-Ingraham & P.G. Martin, Univ. Toronto, HOBYS Key Programme (F. Motte)
Explanation from: http://www.nasa.gov/mission_pages/herschel/multimedia/pia16881.html

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Building a Lunar Base with 3D Printing

Building a base on the Moon could theoretically be made much simpler by using a 3D printer to construct it from local materials.

The concept was recently endorsed by the European Space Agency (ESA) which is now collaborating with architects to gauge the feasibility of 3D printing using lunar soil.

“Terrestrial 3D printing technology has produced entire structures,” explained Laurent Pambaguian, heading the project for ESA. “Our industrial team investigated if it could similarly be employed to build a lunar habitat.”

According to Pambaguian, ESA’s partners have devised a weight-bearing “catenary” dome design with a cellular structured wall to help shield against micrometeoroids and space radiation – incorporating a pressurized inflatable to shelter astronauts.

Meanwhile, a hollow closed-cell structure – somewhat reminiscent of bird bones – provides a combination of strength and weight. The base’s design was guided in turn by the properties of 3D-printed lunar soil, with a 1.5 ton building block produced as a demonstration.

“3D printing offers a potential means of facilitating lunar settlement with reduced logistics from Earth,” said Scott Hovland of ESA’s human spaceflight team. “The new possibilities this work opens up can then be considered by international space agencies as part of the current development of a common exploration strategy.”

Essentially, 3D “printouts” are built up layer by layer. A mobile printing array of nozzles on a 6 m frame sprays a binding solution onto a sand-like building material. First, the simulated lunar material is mixed with magnesium oxide to turn it into ‘paper’ to print with. Then for the structural ‘ink’ a binding salt is applied to convert the material to a stone-like solid.

Current 3D printers build at a rate of around 2 m per hour, while next-gen designs should attain 3.5 m per hour, completing an entire building in a week.

Images Credit: ESA/Foster + Partners
Explanation from: http://lunarscience.nasa.gov/articles/building-a-lunar-base-with-3d-printing/

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Mammatus Clouds over Saskatchewan

Normal cloud bottoms are flat. This is because moist warm air that rises and cools will condense into water droplets at a specific temperature, which usually corresponds to a very specific height. As water droplets grow, an opaque cloud forms. Under some conditions, however, cloud pockets can develop that contain large droplets of water or ice that fall into clear air as they evaporate. Such pockets may occur in turbulent air near a thunderstorm. Resulting mammatus clouds can appear especially dramatic if sunlit from the side. These mammatus clouds were photographed over Regina, Saskatchewan, Canada in 2011.

Image Credit: Craig Lindsay
Explanation from: http://apod.nasa.gov/apod/ap121023.html

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Earth - The Water Planet

Viewed from space, the most striking feature of our planet is the water. In both liquid and frozen form, it covers 75% of the Earth’s surface. It fills the sky with clouds. Water is practically everywhere on Earth, from inside the rocky crust to inside our cells.

This detailed, photo-like view of Earth is based largely on observations from the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite. It is one of many images of our watery world featured in a new story examining water in all of its forms and functions.

Here is an excerpt:

“In all, the Earth’s water content is about 1.39 billion cubic kilometers (331 million cubic miles), with the bulk of it, about 96.5%, being in the global oceans. As for the rest, approximately 1.7% is stored in the polar icecaps, glaciers, and permanent snow, and another 1.7% is stored in groundwater, lakes, rivers, streams, and soil.

Only a thousandth of 1% of the water on Earth exists as water vapor in the atmosphere. Despite its small amount, this water vapor has a huge influence on the planet. Water vapor is a powerful greenhouse gas, and it is a major driver of the Earth’s weather and climate as it travels around the globe, transporting heat with it.

For human needs, the amount of freshwater for drinking and agriculture is particularly important. Freshwater exists in lakes, rivers, groundwater, and frozen as snow and ice. Estimates of groundwater are particularly difficult to make, and they vary widely. Groundwater may constitute anywhere from approximately 22 to 30% of fresh water, with ice accounting for most of the remaining 78 to 70%."

Image Credit: Robert Simmon and Marit Jentoft-Nilsen/MODIS
Explanation from: http://earthobservatory.nasa.gov/IOTD/view.php?id=46209

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Star-Forming Region S106

The bipolar star-forming region, called Sharpless 2-106, looks like a soaring, celestial snow angel. The outstretched "wings" of the nebula record the contrasting imprint of heat and motion against the backdrop of a colder medium.

Sharpless 2-106, Sh2-106 or S106 for short, lies nearly 2,000 light-years from us. The nebula measures several light-years in length. It appears in a relatively isolated region of the Milky Way galaxy.

A massive, young star, IRS 4 (Infrared Source 4), is responsible for the furious activity we see in the nebula. Twin lobes of super-hot gas, glowing blue in this image, stretch outward from the central star. This hot gas creates the "wings" of our angel.

A ring of dust and gas orbiting the star acts like a belt, cinching the expanding nebula into an "hourglass" shape. Hubble's sharp resolution reveals ripples and ridges in the gas as it interacts with the cooler interstellar medium.

Dusky red veins surround the blue emission from the nebula. The faint light emanating from the central star reflects off of tiny dust particles. This illuminates the environment around the star, showing darker filaments of dust winding beneath the blue lobes.

Detailed studies of the nebula have also uncovered several hundred brown dwarfs. At purely infrared wavelengths, more than 600 of these sub-stellar objects appear. These "failed" stars weigh less than a tenth of our Sun. Because of their low mass, they cannot produce sustained energy through nuclear fusion like our Sun does. They encompass the nebula in a small cluster.

The Hubble images were taken in February 2011 with the Wide Field Camera 3. Visible narrow-band filters that isolate the hydrogen gas were combined with near-infrared filters that show structure in the cooler gas and dust.

Image Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)Explanation from: http://hubblesite.org/newscenter/archive/releases/2011/38/image/a/

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The M106 Galaxy

Working with astronomical image processors at the Space Telescope Science Institute in Baltimore, Md., renowned astrophotographer Robert Gendler has taken science data from the Hubble Space Telescope (HST) archive and combined it with his own ground-based observations to assemble a photo illustration of the magnificent spiral galaxy M106.

Gendler retrieved archival Hubble images of M106 to assemble a mosaic of the center of the galaxy. He then used his own and fellow astrophotographer Jay GaBany's observations of M106 to combine with the Hubble data in areas where there was less coverage, and finally, to fill in the holes and gaps where no Hubble data existed.

The center of the galaxy is composed almost entirely of HST data taken by the Advanced Camera for Surveys, Wide Field Camera 3, and Wide Field Planetary Camera 2 detectors. The outer spiral arms are predominantly HST data colorized with ground-based data taken by Gendler's and GaBany's 12.5-inch and 20-inch telescopes, located at very dark remote sites in New Mexico. The image also reveals the optical component of the "anomalous arms" of M106, seen here as red, glowing hydrogen emission.

Robert Gendler is a physician by profession but has been active in astrophotography for two decades. Robert started taking astro-images from his driveway in suburban Connecticut. He then spent several years imaging remotely from places like New Mexico and Western Australia. More recently, Robert has been spending his time assembling hybrid images from multiple data sources including the Hubble Legacy Archive. 

This portrait of M106 contains only the inner structure around the halo and nucleus of this Seyfert II active galaxy. Large amounts of gas from the galaxy are thought to be falling into and fueling a supermassive black hole contained in the nucleus. Also known as NGC 4258, M106 lies 23.5 million light-years away, in the constellation Canes Venatici.

Image Credit:NASA, ESA, the Hubble Heritage Team (STScI/AURA), and R. Gendler (for the Hubble Heritage Team)
Explanation from: http://hubblesite.org/newscenter/archive/releases/2013/06/image/a/

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A cloud of ash above Puyehue-Cordón Caulle Volcano

Osorno, Los Lagos, Chile

June 5, 2011

Image Credit & Copyright: Claudio Santana

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Comet C/2011 L4 - PANSTARRS

Still looking for that comet? Comet PanSTARRS (C/2011 L4) naked-eye appearance in the northern hemisphere is described by successful comet spotters as a dim star with faint a tail. If you want to catch it the next few days could be your best bet. Start looking low and almost due west about 45 minutes after sunset. Of course, clear skies and a pair of binoculars should help a lot. Sky photographer Jean-Luc Dauvergne found suitable weather and western horizon for this comet and crescent Moon portrait after a road trip on March 13. Seeing PanSTARRS for the first time, he recorded the beautiful twilight scene with a telephoto lens near historical Alesia in France.

Image Credit & Copyright: Jean-Luc Dauvergne
Explanation from: http://apod.nasa.gov/apod/ap130316.html

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Hubble Panoramic View of Orion Nebula Reveals Thousands of Stars

This dramatic image offers a peek inside a cavern of roiling dust and gas where thousands of stars are forming. The image, taken by the Advanced Camera for Surveys (ACS) aboard NASA's Hubble Space Telescope, represents the sharpest view ever taken of this region, called the Orion Nebula. More than 3,000 stars of various sizes appear in this image. Some of them have never been seen in visible light. These stars reside in a dramatic dust-and-gas landscape of plateaus, mountains, and valleys that are reminiscent of the Grand Canyon.

The Orion Nebula is a picture book of star formation, from the massive, young stars that are shaping the nebula to the pillars of dense gas that may be the homes of budding stars. The bright central region is the home of the four heftiest stars in the nebula. The stars are called the Trapezium because they are arranged in a trapezoid pattern. Ultraviolet light unleashed by these stars is carving a cavity in the nebula and disrupting the growth of hundreds of smaller stars. Located near the Trapezium stars are stars still young enough to have disks of material encircling them. These disks are called protoplanetary disks or "proplyds" and are too small to see clearly in this image. The disks are the building blocks of solar systems.

The bright glow at upper left is from M43, a small region being shaped by a massive, young star's ultraviolet light. Astronomers call the region a miniature Orion Nebula because only one star is sculpting the landscape. The Orion Nebula has four such stars. Next to M43 are dense, dark pillars of dust and gas that point toward the Trapezium. These pillars are resisting erosion from the Trapezium's intense ultraviolet light. The glowing region on the right reveals arcs and bubbles formed when stellar winds - streams of charged particles ejected from the Trapezium stars — collide with material.

The faint red stars near the bottom are the myriad brown dwarfs that Hubble spied for the first time in the nebula in visible light. Sometimes called "failed stars," brown dwarfs are cool objects that are too small to be ordinary stars because they cannot sustain nuclear fusion in their cores the way our Sun does. The dark red column, below, left, shows an illuminated edge of the cavity wall.

The Orion Nebula is 1,500 light-years away, the nearest star-forming region to Earth. Astronomers used 520 Hubble images, taken in five colors, to make this picture. They also added ground-based photos to fill out the nebula. The ACS mosaic covers approximately the apparent angular size of the full moon.

The Orion observations were taken between 2004 and 2005.

Image Credit: NASA,ESA, M. Robberto (Space Telescope Science Institute/ESA) and the Hubble Space Telescope Orion Treasury Project Team
Explanation from: http://hubblesite.org/newscenter/archive/releases/2006/01/image/a/

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A cloud of ash above Puyehue Volcano

Osorno, Los Lagos, Chile

June 5, 2011

Image Credit & Copyright: Claudio Santana

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Quiet Interlude in Solar Max

Something unexpected is happening on the Sun. 2013 was supposed to be the year of "solar maximum," the peak of the 11-year sunspot cycle. Yet 2013 has arrived and solar activity is relatively low. Sunspot numbers are well below their values from 2011, and strong solar flares have been infrequent.

The image above shows the Earth-facing surface of the Sun on February 28, 2013, as observed by the Helioseismic and Magnetic Imager (HMI) on NASA's Solar Dynamics Observatory. HMI observes the solar disk at 6173 Ångstroms, a wavelength designed to study surface oscillations and the magnetic field. HMI observed just a few small sunspots on an otherwise clean face, which is usually riddled with many spots during peak solar activity.

Image Credit: NASA/SDO
Explanation from: http://www.nasa.gov/multimedia/imagegallery/image_feature_2464.html

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Ancient Mars Could Have Supported Life

An analysis of a rock sample collected by NASA's Curiosity rover shows ancient Mars could have supported living microbes.

Scientists identified sulfur, nitrogen, hydrogen, oxygen, phosphorus and carbon -- some of the key chemical ingredients for life -- in the powder Curiosity drilled out of a sedimentary rock near an ancient stream bed in Gale Crater on the Red Planet last month.

"A fundamental question for this mission is whether Mars could have supported a habitable environment," said Michael Meyer, lead scientist for NASA's Mars Exploration Program at the agency's headquarters in Washington. "From what we know now, the answer is yes."

Clues to this habitable environment come from data returned by the rover's Sample Analysis at Mars (SAM) and Chemistry and Mineralogy (CheMin) instruments. The data indicate the Yellowknife Bay area the rover is exploring was the end of an ancient river system or an intermittently wet lake bed that could have provided chemical energy and other favorable conditions for microbes. The rock is made up of a fine-grained mudstone containing clay minerals, sulfate minerals and other chemicals. This ancient wet environment, unlike some others on Mars, was not harshly oxidizing, acidic or extremely salty.

The patch of bedrock where Curiosity drilled for its first sample lies in an ancient network of stream channels descending from the rim of Gale Crater. The bedrock also is fine-grained mudstone and shows evidence of multiple periods of wet conditions, including nodules and veins.

Curiosity's drill collected the sample at a site just a few hundred yards away from where the rover earlier found an ancient streambed in September 2012.

"Clay minerals make up at least 20 percent of the composition of this sample," said David Blake, principal investigator for the CheMin instrument at NASA's Ames Research Center in Moffett Field, Calif.

These clay minerals are a product of the reaction of relatively fresh water with igneous minerals, such as olivine, also present in the sediment. The reaction could have taken place within the sedimentary deposit, during transport of the sediment, or in the source region of the sediment. The presence of calcium sulfate along with the clay suggests the soil is neutral or mildly alkaline.

Scientists were surprised to find a mixture of oxidized, less-oxidized, and even non-oxidized chemicals, providing an energy gradient of the sort many microbes on Earth exploit to live. This partial oxidation was first hinted at when the drill cuttings were revealed to be gray rather than red.

"The range of chemical ingredients we have identified in the sample is impressive, and it suggests pairings such as sulfates and sulfides that indicate a possible chemical energy source for micro-organisms," said Paul Mahaffy, principal investigator of the SAM suite of instruments at NASA's Goddard Space Flight Center in Greenbelt, Md.

An additional drilled sample will be used to help confirm these results for several of the trace gases analyzed by the SAM instrument.

"We have characterized a very ancient, but strangely new 'gray Mars' where conditions once were favorable for life," said John Grotzinger, Mars Science Laboratory project scientist at the California Institute of Technology in Pasadena, Calif. "Curiosity is on a mission of discovery and exploration, and as a team we feel there are many more exciting discoveries ahead of us in the months and years to come."

Scientists plan to work with Curiosity in the "Yellowknife Bay" area for many more weeks before beginning a long drive to Gale Crater's central mound, Mount Sharp. Investigating the stack of layers exposed on Mount Sharp, where clay minerals and sulfate minerals have been identified from orbit, may add information about the duration and diversity of habitable conditions.

Image Credit: Daein Ballard
Explanation from: http://www.nasa.gov/mission_pages/msl/news/msl20130312.html

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NASA’s SDO Observes Earth, Lunar Transits in Same Day

On March 2, 2013, NASA’s Solar Dynamics Observatory (SDO) entered its semiannual eclipse season, a period of three weeks when Earth blocks its view of the Sun for a period of time each day. On March 11, however, SDO was treated to two transits. Earth blocked SDO’s view of the Sun from about 2:15 to 3:45 a.m. EDT. Later in the same day, from around 7:30 to 8:45 a.m. EDT, the Moon moved in front of the Sun for a partial eclipse.

When Earth blocks the Sun, the boundaries of Earth’s shadow appear fuzzy, since SDO can see some light from the Sun coming through Earth’s atmosphere. The line of Earth appears almost straight, since Earth - from SDO’s point of view - is so large compared to the Sun.

The eclipse caused by the Moon looks far different. Since the Moon has no atmosphere, its curved shape can be seen clearly, and the line of its shadow is crisp and clean. Any spacecraft observing the Sun from an orbit around Earth has to contend with such eclipses, but SDO's orbit is designed to minimize them as much as possible, with only two three-week eclipse seasons each year. The 2013 spring eclipse season continues until March 26. The fall season will begin on September 2.

Images Credit: NASA/SDO
Explanation from: http://www.nasa.gov/mission_pages/sdo/news/eclipse-spring2013.html

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Aurora over Kongsberg

Kongsberg, Norway

December 4, 2010

Image Credit & Copyright: Odd Smedsrud

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Sakurajima Volcano with Lightning

Why does a volcanic eruption sometimes create lightning? On this picture, the Sakurajima volcano in southern Japan was caught erupting in early January 2013. Magma bubbles so hot they glow shoot away as liquid rock bursts through the Earth's surface from below. This image is particularly notable, however, for the lightning bolts caught near the volcano's summit. Why lightning occurs even in common thunderstorms remains a topic of research, and the cause of volcanic lightning is even less clear. Surely, lightning bolts help quench areas of opposite but separated electric charges. One hypothesis holds that catapulting magma bubbles or volcanic ash are themselves electrically charged, and by their motion create these separated areas. Other volcanic lightning episodes may be facilitated by charge-inducing collisions in volcanic dust. Lightning is usually occurring somewhere on Earth, typically over 40 times each second.

Image Credit & Copyright: Martin Rietze
Explanation from: http://apod.nasa.gov/apod/ap130311.html

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Aurora over Langesund

Langesund, Norway

October 10, 2012

Image Credit & Copyright: Hugo Løhre

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Summer Lightning near Keota

The Pawnee National Grasslands in Colorado is an exceptional place both to observe nature and to stargaze. Observers have a nearly unobstructed view of the horizon. During the summer months, lightning can be seen miles away, and the night sky is generally free of annoying light pollution.

Image Credit: Robert Arn

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Tornado & Lightning

Lightning can serve as a natural sensing tool that allows scientists to understand what else could be happening in a storm

Image Credit: F. Smith

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The Milky Way Galaxy over Devils Tower

Was Devils Tower once an explosive volcano? Famous for its appearance in films such as Close Encounters, the origin of Devil's Tower in Wyoming, USA is still debated, with a leading hypothesis holding that it is a hardened lava plume that probably never reached the surface to become a volcano. The lighter rock that once surrounded the dense volcanic neck has now eroded away, leaving the dramatic tower. High above, the central band of the Milky Way Galaxy arches across the sky. Many notable sky objects are visible, including dark strands of the Pipe Nebula and the reddish Lagoon Nebula to the tower's right. Green grass and trees line the moonlit foreground, while clouds appear near the horizon to the tower's left. Unlike many other international landmarks, mountaineers are permitted to climb Devils Tower.

Image Credit & Copyright: Wally Pacholka
Explanation: http://apod.nasa.gov/apod/ap090729.html

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Eclipse over the Temple of Poseidon

What's happened to the Sun? The Moon moved to partly block the Sun for a few minutes in January 2010 as a partial solar eclipse became momentarily visible across part of planet Earth. In this single exposure image, meticulous planning enabled careful photographers to capture the partially eclipsed Sun well posed just above the ancient ruins of the Temple of Poseidon in Sounio, Greece. Unexpectedly, clouds covered the top of the Sun, while a flying bird was caught in flight just to the right of the eclipse. At its fullest extent from some locations, the Moon was seen to cover the entire middle of the Sun, leaving the surrounding ring of fire of an annular solar eclipse.

Image Credit & Copyright: Chris Kotsiopoulos & Anthony Ayiomamitis

Explanation from: http://apod.nasa.gov/apod/ap100118.html

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Earth's Shadow

The dark, inner shadow of planet Earth is called the umbra. Shaped like a cone extending into space, the umbra has a circular cross section that can be most easily seen during a lunar eclipse. For example, in August 2008, the Full Moon slid across the northern edge of the umbra. Entertaining moon watchers throughout Earth's eastern hemisphere, the lunar passage created a deep but partial lunar eclipse. This composite image uses successive pictures recorded during the eclipse from Athens, Greece to trace out a large part of the umbra's curved edge. The result nicely illustrates the relative size of the umbra's cross section at the distance of the Moon, as well as the Moon's path through the Earth's shadow.

Image Credit & Copyright: Anthony Ayiomamitis
Explanation from: http://apod.nasa.gov/apod/ap080820.html

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Shooting a Laser at the Galactic Centre

The sky above Paranal on 21 July 2007. Two 8.2-m telescopes of ESO's VLT are seen against the wonderful backdrop of the myriad of stars and dust that makes the Milky Way. Just above Yepun, Unit Telescope number 4, the Small Magellanic Cloud - a satellite galaxy of the Milky Way - is shining. A laser beam is coming out of Yepun, aiming at the Galactic Centre. It is used to obtain images that are free from the blurring effect of the atmosphere. On this image, the laser beam looks slightly artificial. This is a side effect due to saturation caused by the long exposure time. Planet Jupiter is seen as the brightest object on the upper right, next to the star Antares. Image taken by ESO astronomer Yuri Beletsky.

Image Credit: ESO/Yuri Beletsky
Explanation from: http://www.eso.org/public/images/eso0733b/

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Sunrise over Cape Sounion

The Sun is a moving target. Its annual motion through planet Earth's sky tracks north and south, from solstice to solstice, as the seasons change. On December 21st, the solstice marking the first day of winter in the northern hemisphere and summer in the south, the Sun rose at its southernmost point along the eastern horizon. Earlier December, 2009, looking toward the Aegean Sea from a well-chosen vantage point at Cape Sounion, Greece, it also rose in this dramatic scene. In the foreground lies the twenty-four hundred year old Temple of Poseidon.

Image Credit & Copyright: Anthony Ayiomamitis
Explanation from: http://apod.nasa.gov/apod/ap091223.html

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