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Astronomy Picture of the Day (General/Chat)

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  • 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...
  • Astronomy Picture of the Day -- Pluto at Night

    06/09/2016 2:44:32 PM PDT · by SunkenCiv · 13 replies
    NASA ^ | Thursday, June 09, 2016 | (see photo credit)
    Explanation: The night side of Pluto spans this shadowy scene. The spacebased view with the Sun behind the distant world was captured by New Horizons last July. The spacecraft was at a range of over 21,000 kilometers, about 19 minutes after its closest approach. A denizen of the Kuiper Belt in dramatic silhouette, the image also reveals Pluto's tenuous, surprisingly complex layers of hazy atmosphere. The crescent twilight landscape near the top of the frame includes southern areas of nitrogen ice plains informally known as Sputnik Planum and rugged mountains of water-ice in the Norgay Montes.
  • Astronomy Picture of the Day -- The Horsehead Nebula in Infrared from Hubble

    06/08/2016 8:23:58 AM PDT · by SunkenCiv · 3 replies
    NASA ^ | Wednesday, June 08, 2016 | (see photo credit)
    Explanation: While drifting through the cosmos, a magnificent interstellar dust cloud became sculpted by stellar winds and radiation to assume a recognizable shape. Fittingly named the Horsehead Nebula, it is embedded in the vast and complex Orion Nebula (M42). A potentially rewarding but difficult object to view personally with a small telescope, the above gorgeously detailed image was taken in 2013 in infrared light by the orbiting Hubble Space Telescope in honor of the 23rd anniversary of Hubble's launch. The dark molecular cloud, roughly 1,500 light years distant, is cataloged as Barnard 33 and is seen above primarily because it...
  • Astronomy Picture of the Day -- Night on Venus in Infrared from Orbiting Akatsuki

    06/07/2016 5:36:48 AM PDT · by SunkenCiv · 18 replies
    NASA ^ | Tuesday, June 07, 2016 | (see photo credit)
    Explanation: Why is Venus so different from Earth? To help find out, Japan launched the robotic Akatsuki spacecraft which entered orbit around Venus late last year after an unplanned five-year adventure around the inner Solar System. Even though Akatsuki has passed its original planned lifetime, the spacecraft and its instruments are operating so well that much of its original mission has been reinstated. In the featured image taken by Akatsuki late last month, Venus was captured in infrared light showing a surprising amount of atmospheric structure on its night side. The vertical orange terminator stripe between night and day is...
  • Astronomy Picture of the Day -- The Supernova and Cepheids of Spiral Galaxy UGC 9391

    06/06/2016 3:59:04 AM PDT · by SunkenCiv · 3 replies
    NASA ^ | Monday, June 06, 2016 | (see photo credit)
    Explanation: What can this galaxy tell us about the expansion rate of the universe? Perhaps a lot because UGC 9391, featured, not only contains Cepheid variable stars (red circles) but also a recent Type Ia supernova (blue X). Both types of objects have standard brightnesses, with Cepheids typically being seen relatively nearby, while supernovas are seen much further away. Therefore, this spiral is important because it allows a calibration between the near and distant parts of our universe. Unexpectedly, a recent analysis of new Hubble data from UGC 9391 and several similar galaxies has bolstered previous indications that Cepheids and...
  • Astronomy Picture of the Day -- Comet PanSTARRS and the Helix Nebula

    06/05/2016 4:16:28 PM PDT · by SunkenCiv · 17 replies
    NASA ^ | Sunday, June 05, 2016 | (see photo credit)
    Explanation: It's rare that such different objects are imaged so close together. Such an occasion is occurring now, though, and was captured two days ago in combined parallel exposures from the Canary Islands of Spain. On the lower right, surrounded by a green coma and emanating an unusually split blue ion tail diagonally across the frame, is Comet C/2013 X1 (PanSTARRS). This giant snowball has been falling toward our Sun and brightening since its discovery in 2013. Although Comet PannSTARRS is a picturesque target for long-duration exposures of astrophotography, it is expected to be only barely visible to the unaided...