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Astronomy Picture of the Day (General/Chat)

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  • Astronomy Picture of the Day -- From Alpha to Omega in Crete

    06/29/2016 7:39:42 AM PDT · by SunkenCiv · 7 replies
    NASA ^ | Wednesday, June 29, 2016 | (see photo credit)
    Explanation: This beautiful telephoto composition spans light-years in a natural night skyscape from the island of Crete. Looking south, exposures both track the stars and record a fixed foreground in three merged panels that cover a 10x12 degree wide field of view. The May 15 waxing gibbous moonlight illuminates the church and mountainous terrain. A mere 18 thousand light-years away, huge globular star cluster Omega Centauri (NGC 5139) shining above gives a good visual impression of its appearance in binoculars on that starry night. Active galaxy Centaurus A (NGC 5128) is near the top of the frame, some 11 million...
  • Astronomy Picture of the Day -- Juno Mission Trailer

    06/28/2016 10:45:32 AM PDT · by SunkenCiv · 8 replies
    NASA ^ | Tuesday, June 28, 2016 | (see photo credit)
    Explanation: What will NASA's Juno spacecraft find when it reaches Jupiter next Monday? Very little, if Juno does not survive Jupiter Orbit Insertion, a complex series of operations in an unknown environment just above Jupiter's cloud tops. If successful, as explained in the featured video, Juno will swoop around Jupiter, passing closer than any previous spacecraft. The goal is to decelerate, enter into a highly elliptical orbit, and begin two years of science operations. Juno's science mission objectives include mapping Jupiter's deep structure, determining how much water is in Jupiter's atmosphere, and exploring Jupiter's powerful magnetic field and how it...
  • Astronomy Picture of the Day -- Anticrepuscular Rays over Colorado (II)

    06/28/2016 10:40:43 AM PDT · by SunkenCiv · 10 replies
    NASA ^ | Monday, June 27, 2016 | (see photo credit)
    Explanation: What's happening over the horizon? Although the scene may appear somehow supernatural, nothing more unusual is occurring than a setting Sun and some well placed clouds. Pictured above are anticrepuscular rays. To understand them, start by picturing common crepuscular rays that are seen any time that sunlight pours though scattered clouds. Now although sunlight indeed travels along straight lines, the projections of these lines onto the spherical sky are great circles. Therefore, the crepuscular rays from a setting (or rising) sun will appear to re-converge on the other side of the sky. At the anti-solar point 180 degrees around...
  • Astronomy Picture of the Day -- Jupiter's Clouds from New Horizons

    06/26/2016 10:54:07 AM PDT · by SunkenCiv · 12 replies
    NASA ^ | Sunday, June 26, 2016 | (see photo credit)
    Explanation: The New Horizons spacecraft took some stunning images of Jupiter on its way out to Pluto. Famous for its Great Red Spot, Jupiter is also known for its regular, equatorial cloud bands, visible through even modest sized telescopes. The featured image, horizontally compressed, was taken in 2007 near Jupiter's terminator and shows the Jovian giant's wide diversity of cloud patterns. On the far left are clouds closest to Jupiter's South Pole. Here turbulent whirlpools and swirls are seen in a dark region, dubbed a belt, that rings the planet. Even light colored regions, called zones, show tremendous structure, complete...
  • Astronomy Picture of the Day -- Strawberry to Honey Moonrise [Popsicle stick]

    06/25/2016 4:43:25 AM PDT · by SunkenCiv · 3 replies
    NASA ^ | Saturday, June 25, 2016 | (see photo credit)
    Explanation: Near the horizon the Full Moon often seems to loom large, swollen in appearance by the famous Moon illusion. But timelapse images demonstrate that the Moon's apparent size doesn't really change as it climbs toward the zenith. Its color does, though. Recording a frame every 10 seconds, this image shows how dramatic that color change can be. The composite follows a solstice Full Moon climbing above a rugged horizon over northwestern Indiana. A shrinking line-of-sight through planet Earth's dense and dusty atmosphere shifted the moonlight from strawberry red through honey-colored and paler yellowish hues. That change seems appropriate for...
  • Astronomy Picture of the Day -- Sagittarius Sunflowers

    06/23/2016 11:09:57 PM PDT · by SunkenCiv · 9 replies
    NASA ^ | Friday, June 24, 2016 | (see photo credit)
    Explanation: These three bright nebulae are often featured in telescopic tours of the constellation Sagittarius and the crowded starfields of the central Milky Way. In fact, 18th century cosmic tourist Charles Messier cataloged two of them; M8, the large nebula left of center, and colorful M20 near the bottom of the frame The third, NGC 6559, is right of M8, separated from the larger nebula by dark dust lanes. All three are stellar nurseries about five thousand light-years or so distant. The expansive M8, over a hundred light-years across, is also known as the Lagoon Nebula. M20's popular moniker is...
  • Astronomy Picture of the Day -- Solstice Dawn and Full Moonset

    06/23/2016 8:38:01 AM PDT · by SunkenCiv · 5 replies
    NASA ^ | Thursday, June 23, 2016 | (see photo credit)
    Explanation: A Full Moon sets as the Solstice Sun rises in this June 20 dawn skyscape. Captured from a nearby peak in central California, planet Earth, the scene looks across the summit of Mount Hamilton and Lick Observatory domes on a calendar date that marks an astronomical change of seasons and hemispherical extremes of daylight hours. Earth's shadow stretches toward the Santa Cruz Mountains on the western horizon. Just above the atmospheric grey shadowband is a more colorful anti-twilight arch, a band of reddened, backscattered sunlight also known as the Belt of Venus. The interplay of solstice dates and lunar...
  • Astronomy Picture of the Day -- Cirrus over Paris

    06/22/2016 4:45:04 AM PDT · by SunkenCiv · 4 replies
    NASA ^ | Wednesday, June 22, 2016 | (see photo credit)
    Explanation: What's that over Paris? Cirrus. Typically, cirrus clouds appear white or gray when reflecting sunlight, can appear dark at sunset (or sunrise) against a better lit sky. Cirrus are among the highest types of clouds and are usually thin enough to see stars through. Cirrus clouds may form from moisture released above storm clouds and so may herald the arrival of a significant change in weather. Conversely, cirrus clouds have also been seen on Mars, Jupiter, Saturn, Titan, Uranus, and Neptune. The featured image was taken two days ago from a window in District 15, Paris, France, Earth. The...
  • Astronomy Picture of the Day -- NGC 6814: Grand Design Spiral Galaxy from Hubble

    06/21/2016 1:24:44 PM PDT · by SunkenCiv · 8 replies
    NASA ^ | Tuesday, June 21, 2016 | (see photo credit)
    Explanation: In the center of this serene stellar swirl is likely a harrowing black-hole beast. The surrounding swirl sweeps around billions of stars which are highlighted by the brightest and bluest. The breadth and beauty of the display give the swirl the designation of a grand design spiral galaxy. The central beast shows evidence that it is a supermassive black hole about 10 million times the mass of our Sun. This ferocious creature devours stars and gas and is surrounded by a spinning moat of hot plasma that emits blasts of X-rays. The central violent activity gives it the designation...
  • Astronomy Picture of the Day -- Sunrise Solstice over Stonehenge

    06/20/2016 3:35:50 AM PDT · by SunkenCiv · 19 replies
    NASA ^ | Monday, June 20, 2016 | (see photo credit)
    Explanation: Today the Sun reaches its northernmost point in planet Earth's sky. Called a solstice, the date traditionally marks a change of seasons -- from spring to summer in Earth's Northern Hemisphere and from fall to winter in Earth's Southern Hemisphere. The featured image was taken during the week of the 2008 summer solstice at Stonehenge in United Kingdom, and captures a picturesque sunrise involving fog, trees, clouds, stones placed about 4,500 years ago, and a 4.5 billion year old large glowing orb. Even given the precession of the Earth's rotational axis over the millennia, the Sun continues to rise...
  • Astronomy Picture of the Day -- Galaxy and Planets Beyond Bristlecone Pines

    06/19/2016 6:48:50 AM PDT · by SunkenCiv · 9 replies
    NASA ^ | Sunday, June 19, 2016 | (see photo credit)
    Explanation: What's older than these ancient trees? Nobody you know -- but almost everything in the background of this picture. The trees are impressively old -- each part of the Ancient Bristlecone Pine Forest located in eastern California, USA. There, many of the oldest trees known are located, some dating as far back as about 5,000 years. Seemingly attached to tree branches, but actually much farther in the distance, are the bright orbs of Saturn (left) and Mars. These planets formed along with the Earth and the early Solar System much earlier -- about 4.5 billion years ago. Swooping down...
  • Astronomy Picture of the Day -- Sputnik Planum vs. Krun Macula

    06/18/2016 12:30:40 PM PDT · by SunkenCiv · 3 replies
    NASA ^ | Saturday, June 18, 2016 | (see photo credit)
    Explanation: Pluto's pitted plains meet rugged highlands in this stunning view. On the left lies a southeastern extent of the bright region still informally known as Sputnik Planum. At right the edge of a dark region, informally Krun Macula, rises some 2.5 kilometers above the icy plains. Along the boundary, connected clusters of large pits form deep valleys, some over 40 kilometers long with shadowy floors. Nitrogen ice is likely responsible for the more reflective plains. The dark red color of the highlands is thought to be from complex compounds called tholins, a product of ultraviolet light induced chemical reactions...
  • Astronomy Picture of the Day -- Comet PanSTARRS in the Southern Fish

    06/17/2016 10:22:46 AM PDT · by SunkenCiv · 1 replies
    NASA ^ | Friday, June 17, 2016 | (see photo credit)
    Explanation: Now approaching our fair planet this Comet PanSTARRS (C/2013 X1) will come closest on June 21-22, a mere 5.3 light-minutes away. By then its appearance low in northern hemisphere predawn skies (high in the south), will be affected by the light of a nearly Full Moon, though. Still the comet's pretty green coma is about the apparent size of the Full Moon in this telescopic portrait, captured on June 12 from the southern hemisphere's Siding Spring Observatory. The deep image also follows a broad, whitish dust tail up and toward the left in the frame, sweeping away from the...
  • Astronomy Picture of the Day -- Northern Lights above Lofoten

    06/16/2016 8:56:16 AM PDT · by SunkenCiv · 3 replies
    NASA ^ | Thursday, June 16, 2016 | (see photo credit)
    Explanation: The Aurora Borealis or northern lights are familiar visitors to night skies above the village of Reine in the Lofoten Islands, Norway, planet Earth. In this scene, captured from a mountaintop camp site, the auroral curtains do seem to create an eerie tension with the coastal lights though. A modern perspective on the world at night, the stunning image was chosen as the over all winner in The World at Night's 2016 International Earth and Sky Photo Contest. Selections were made from over 900 entries highlighting the beauty of the night sky and its battle with light pollution.
  • Astronomy Picture of the Day -- GW151226: A Second Confirmed Source of Gravitational Radiation

    06/15/2016 1:43:27 PM PDT · by SunkenCiv · 12 replies
    NASA ^ | Wednesday, June 15, 2016 | (see photo credit)
    Explanation: A new sky is becoming visible. When you look up, you see the sky as it appears in light -- electromagnetic radiation. But just over the past year, humanity has begun to see our once-familiar sky as it appears in a different type of radiation -- gravitational radiation. Today, the LIGO collaboration is reporting the detection of GW151226, the second confirmed flash of gravitational radiation after GW150914, the historic first detection registered three months earlier. As its name implies, GW151226 was recorded in late December of 2015. It was detected simultaneously by both LIGO facilities in Washington and Louisiana,...
  • Astronomy Picture of the Day -- The North America and Pelican Nebulas

    06/13/2016 9:49:44 PM PDT · by SunkenCiv · 2 replies
    NASA ^ | Tuesday, June 14, 2016 | (see photo credit)
    Explanation: Here lie familiar shapes in unfamiliar locations. On the left is an emission nebula cataloged as NGC 7000, famous partly because it resembles our fair planet's continent of North America. The emission region to the right of the North America Nebula is IC 5070, also known for its suggestive outlines as the Pelican Nebula. Separated by a dark cloud of obscuring dust, the two bright nebulae are about 1,500 light-years away. At that distance, the 4 degree wide field of view spans 100 light-years. This spectacular cosmic portrait combines narrow band images to highlight bright ionization fronts with fine...
  • Astronomy Picture of the Day -- Unexplained Dimmings in KIC 8462852

    06/13/2016 9:46:29 PM PDT · by SunkenCiv · 9 replies
    NASA ^ | Monday, June 13, 2016
    Explanation: Why does star KIC 8462852 keep wavering? Nobody knows. A star somewhat similar to our Sun, KIC 8462852 was one of many distant stars being monitored by NASA's robotic Kepler satellite to see if it had planets. Citizen scientists voluntarily co-inspecting the data along with computers found this unusual case where a star's brightness dropped at unexpected times by as much as 20 percent for as long as months -- but then recovered. Common reasons for dimming -- such as eclipses by orbiting planets or stellar companions -- don't match the non-repetitive nature of the dimmings. A currently debated...
  • Astronomy Picture of the Day -- A Roll Cloud Over Uruguay

    06/12/2016 6:40:44 AM PDT · by SunkenCiv · 4 replies
    NASA ^ | Sunday, June 12, 2016 | (see photo credit)
    Explanation: What kind of cloud is this? A type of arcus cloud called a roll cloud. These rare long clouds may form near advancing cold fronts. In particular, a downdraft from an advancing storm front can cause moist warm air to rise, cool below its dew point, and so form a cloud. When this happens uniformly along an extended front, a roll cloud may form. Roll clouds may actually have air circulating along the long horizontal axis of the cloud. A roll cloud is not thought to be able to morph into a tornado. Unlike a similar shelf cloud, a...
  • Astronomy Picture of the Day -- The Fornax Cluster of Galaxies

    06/12/2016 6:37:47 AM PDT · by SunkenCiv · 3 replies
    NASA ^ | Saturday, June 11, 2016 | (see photo credit)
    Explanation: Named for the southern constellation toward which most of its galaxies can be found, the Fornax Cluster is one of the closest clusters of galaxies. About 62 million light-years away, it is almost 20 times more distant than our neighboring Andromeda Galaxy, and only about 10 percent farther than the better known and more populated Virgo Galaxy Cluster. Seen across this two degree wide field-of-view, almost every yellowish splotch on the image is an elliptical galaxy in the Fornax cluster. A standout barred spiral galaxy NGC 1365 is visible on the lower right as a prominent Fornax cluster member....
  • Astronomy Picture of the Day -- NGC 6888: The Crescent Nebula

    06/10/2016 4:07:34 AM PDT · by SunkenCiv · 3 replies
    NASA ^ | Friday, June 10, 2016 | (see photo credit)
    Explanation: NGC 6888, also known as the Crescent Nebula, is a cosmic bubble about 25 light-years across, blown by winds from its central, bright, massive star. This sharp telescopic portrait uses narrow band image data that isolates light from hydrogen and oxygen atoms in the wind-blown nebula. The oxygen atoms produce the blue-green hue that seems to enshroud the detailed folds and filaments. Visible within the nebula, NGC 6888's central star is classified as a Wolf-Rayet star (WR 136). The star is shedding its outer envelope in a strong stellar wind, ejecting the equivalent of the Sun's mass every 10,000...