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Astronomy Picture of the Day (General/Chat)

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  • Astronomy Picture of the Day -- Evaporating Blobs of the Carina Nebula

    04/23/2012 8:40:12 PM PDT · by SunkenCiv · 8 replies
    NASA ^ | April 23, 2012 | (see photo credit)
    Explanation: No, they are not alive -- but they are dying. The unusual blobs found in the Carina nebula, some of which are seen floating on the upper right, might best be described as evaporating. Energetic light and winds from nearby stars are breaking apart the dark dust grains that make the iconic forms opaque. Ironically the blobs, otherwise known as dark molecular clouds, frequently create in their midst the very stars that later destroy them. The floating space mountains pictured above by the orbiting Hubble Space Telescope span a few light months. The Great Nebula in Carina itself spans...
  • Astronomy Picture of the Day -- Flowing Barchan Sand Dunes on Mars

    04/22/2012 8:17:03 PM PDT · by SunkenCiv · 6 replies
    NASA ^ | April 22, 2012 | (see photo credit)
    Explanation: When does Mars act like a liquid? Although liquids freeze and evaporate quickly into the thin atmosphere of Mars, persistent winds may make large sand dunes appear to flow and even drip like a liquid. Visible on the above image right are two flat top mesas in southern Mars when the season was changing from Spring to Summer. A light dome topped hill is also visible on the far left of the image. As winds blow from right to left, flowing sand on and around the hills leaves picturesque streaks. The dark arc-shaped droplets of fine sand are called...
  • Astronomy Picture of the Day -- 3 ATs [Auxiliary Telescopes]

    04/21/2012 7:33:55 AM PDT · by SunkenCiv · 18 replies
    NASA ^ | April 21, 2012 | (see photo credit)
    Explanation: Despite their resemblance to R2D2, these three are not the droids you're looking for. Instead, the enclosures house 1.8 meter Auxiliary Telescopes (ATs) at Paranal Observatory in the Atacama Desert region of Chile. The ATs are designed to be used for interferometry, a technique for achieving extremely high resolution observations, in concert with the observatory's 8 meter Very Large Telescope units. A total of four ATs are operational, each fitted with a transporter that moves the telescope along a track allowing different arrays with the large unit telescopes. To work as an interferometer, the light from each telescope is...
  • Astronomy Picture of the Day -- M57: The Ring Nebula

    04/20/2012 4:24:29 PM PDT · by SunkenCiv · 17 replies
    NASA ^ | April 20, 2012 | (see photo credit)
    Explanation: Except for the rings of Saturn, the Ring Nebula (M57) is probably the most famous celestial band. Its classic appearance is understood to be due to perspective - our view from planet Earth looks down the center of a roughly barrel-shaped cloud of glowing gas. But expansive looping structures are seen to extend far beyond the Ring Nebula's familiar central regions in this intriguing composite of ground based and Hubble Space Telescope images with narrowband image data from Subaru. Of course, in this well-studied example of a planetary nebula, the glowing material does not come from planets. Instead, the...
  • Astronomy Picture of the Day -- Discovery Departs

    04/20/2012 4:23:58 PM PDT · by SunkenCiv · 6 replies
    NASA ^ | April 19, 2012 | (see photo credit)
    Explanation: Climbing into cloudy skies, the Space Shuttle Orbiter Discovery (OV-103) took off from Kennedy Space Center Tuesday at 7 am local time. This time, its final departure from KSC, it rode atop a modified Boeing 747 Shuttle Carrier Aircraft. Following a farewell flyover of the Space Coast, Goddard Space Flight Center, and Washington DC, Discovery headed for Dulles International Airport in Virginia, destined to reside at the Smithsonian's National Air and Space Museum Udvar-Hazy Center. Discovery retires as NASA's most traveled shuttle orbiter, covering more than 148 million miles in 39 missions that included the delivery of the Hubble...
  • Astronomy Picture of the Day -- The Flight Deck of Space Shuttle Endeavour

    04/18/2012 8:13:38 PM PDT · by SunkenCiv · 13 replies
    NASA ^ | April 18, 2012 | (see photo credit)
    Explanation: What would it be like to fly a space shuttle? Although the last of NASA's space shuttles has now been retired, it is still fun to contemplate sitting at the controls of one of the humanity's most sophisticated machines. Pictured above is the flight deck of Space Shuttle Endeavour, the youngest shuttle and the second to last ever launched. The numerous panels and displays allowed the computer-controlled orbiter to enter the top of Earth's atmosphere at greater than the speed of sound and -- just thirty minutes later -- land on a runway like an airplane. The retired space...
  • Astronomy Picture of the Day -- Antares and Clouds

    04/16/2012 9:31:35 PM PDT · by SunkenCiv · 13 replies
    NASA ^ | April 17, 2012 | (see photo credit)
    Explanation: Antares is a huge star. In a class called red supergiant, Antares is about 850 times the diameter of our own Sun, 15 times more massive, and 10,000 times brighter. Antares is the brightest star in the constellation of Scorpius and one of the brighter stars in all the night sky. Located about 550 light years away, Antares is seen on the left surrounded by a yellowish nebula of gas which it has itself expelled. Radiation from Antares' blue stellar companion helps cause the nebular gas to glow. Far behind Antares in the above image is the globular star...
  • Astronomy Picture of the Day -- The Eagle Nebula from Kitt Peak

    04/15/2012 9:12:16 PM PDT · by SunkenCiv · 19 replies
    NASA ^ | April 16, 2012 | (see photo credit)
    Explanation: From afar, the whole thing looks like an Eagle. A closer look at the Eagle Nebula, however, shows the bright region is actually a window into the center of a larger dark shell of dust. Through this window, a brightly-lit workshop appears where a whole open cluster of stars is being formed. In this cavity tall pillars and round globules of dark dust and cold molecular gas remain where stars are still forming. Already visible are several young bright blue stars whose light and winds are burning away and pushing back the remaining filaments and walls of gas and...
  • Astronomy Picture of the Day -- Fata Morgana: A Possibly Titanic Mirage

    04/15/2012 7:49:02 PM PDT · by SunkenCiv · 11 replies
    NASA ^ | April 15, 2012 | (see photo credit)
    Explanation: Did this mirage help sink the Titanic? The optical phenomenon called Fata Morgana can make strange shapes or a false wall of water appear above a watery horizon. When conditions are right, light reflecting off of cold water will be bent by an unusual layer of warm air above to arrive at the observer from several different angles. A conceptually comparable mirage can make a setting Sun appear strangely distorted or a distant pavement appear wet. One hundred years ago today, such a Fata Morgana mirage might have obscured real icebergs from the clear view of crew onboard the...
  • Astronomy Picture of the Day -- Six Moons of Saturn

    04/13/2012 10:46:07 PM PDT · by SunkenCiv · 9 replies
    NASA ^ | April 14, 2012 | (see photo credit)
    Explanation: How many moons does Saturn have? So far 62 have been discovered, the smallest only a fraction of a kilometer across. Six of its largest satellites can be seen here, though, in a sharp Saturnian family portrait taken on March 9. Larger than Earth's Moon and even slightly larger than Mercury, Titan has a diameter of 5,150 kilometers and starts the line-up at the lower left. Continuing to the right across the frame are Mimas, Tethys, [Saturn], Enceladus, Dione, and Rhea at far right. Saturn's first known natural satellite, Titan was discovered in 1655 by Dutch astronomer Christiaan Huygens,...
  • Astronomy Picture of the Day -- A Dust Devil of Mars

    04/12/2012 9:44:43 PM PDT · by SunkenCiv · 21 replies
    NASA ^ | April 13, 2012 | (see photo credit)
    Explanation: It was late in the northern martian spring when the HiRISE camera onboard the Mars Reconnaissance Orbiter spied this local denizen. Tracking south and east (down and right) across the flat, dust-covered Amazonis Planitia the core of the whirling dust devil is about 30 meters in diameter. Lofting dust into the thin martian atmosphere, its plume reaches more than 800 meters above the surface. Not following the path of the dust devil, the plume is blown toward the east by a westerly breeze. Common in this region, dust devils occur as the surface is heated by the Sun, generating...
  • Astronomy Picture of the Day -- Yuri's Planet [ NASA celebrates the USSR]

    04/12/2012 4:29:25 AM PDT · by SunkenCiv · 9 replies
    NASA ^ | April 12, 2012 | (see photo credit)
    Explanation: On another April 12th, in 1961, Soviet cosmonaut Yuri Alexseyevich Gagarin became the first human to see planet Earth from space. Commenting on his view from orbit he reported, "The sky is very dark; the Earth is bluish. Everything is seen very clearly". To celebrate, consider this recent image from the orbiting International Space Station. A stunning view of the planet at night from an altitude of 240 miles, it was recorded on March 28. The lights of Moscow, Russia are near picture center and one of the station's solar panel arrays is on the left. Aurora and the...
  • Astronomy Picture of the Day -- Geostationary Satellites Beyond the Alps [video]

    04/11/2012 3:37:20 AM PDT · by SunkenCiv · 16 replies
    NASA ^ | April 11, 2012 | (see photo credit)
    Explanation: Why don't those stars move? Stars in the sky will typically appear to rise and set as the Earth turns. Those far to the north or south will appear to circle the pole. If you look closely at the above time-lapse movie, however, there are points of light that appear stationary. These objects are not stars but human-launched robotic spacecraft that remain fixed high above the Earth's equator. Called geostationary satellites, they don't fall down because they do orbit the Earth -- they just orbit at exactly the same speed that the Earth rotates. The orbital distance where this...
  • Astronomy Picture of the Day -- A Fox Fur, a Unicorn, and a Christmas Tree

    04/09/2012 9:11:52 PM PDT · by SunkenCiv · 5 replies
    NASA ^ | April 10, 2012 | (see photo credit)
    Explanation: What do the following things have in common: a cone, the fur of a fox, and a Christmas tree? Answer: they all occur in the constellation of the unicorn (Monoceros). Pictured above as a star forming region cataloged as NGC 2264, the complex jumble of cosmic gas and dust is about 2,700 light-years distant and mixes reddish emission nebulae excited by energetic light from newborn stars with dark interstellar dust clouds. Where the otherwise obscuring dust clouds lie close to the hot, young stars they also reflect starlight, forming blue reflection nebulae. The above image spans about 3/4 degree...
  • Astronomy Picture of the Day -- Blue Straggler Stars in Globular Cluster M53

    04/09/2012 7:34:49 PM PDT · by SunkenCiv · 9 replies
    NASA ^ | April 09, 2012 | (see photo credit)
    Explanation: If our Sun were part of M53, the night sky would glow like a jewel box of bright stars. M53, also known as NGC 5024, is one of about 250 globular clusters that survive in our Galaxy. Most of the stars in M53 are older and redder than our Sun, but some enigmatic stars appear to be bluer and younger. These young stars might contradict the hypothesis that all the stars in M53 formed at nearly the same time. These unusual stars are known as blue stragglers and are unusually common in M53. After much debate, blue stragglers are...
  • Astronomy Picture of the Day -- Io: Moon Over Jupiter

    04/07/2012 9:45:56 PM PDT · by SunkenCiv · 10 replies
    NASA ^ | April 08, 2012 | (see photo credit)
    Explanation: How big is Jupiter's moon Io? The most volcanic body in the Solar System, Io (usually pronounced "EYE-oh") is 3,600 kilometers in diameter, about the size of planet Earth's single large natural satellite. Gliding past Jupiter at the turn of the millennium, the Cassini spacecraft captured this awe inspiring view of active Io with the largest gas giant as a backdrop, offering a stunning demonstration of the ruling planet's relative size. Although in the above picture Io appears to be located just in front of the swirling Jovian clouds, Io hurtles around its orbit once every 42 hours at...
  • Astronomy Picture of the Day -- Conjunction Haiku

    04/06/2012 9:35:39 PM PDT · by SunkenCiv · 10 replies
    NASA ^ | April 07, 2012 | (see photo credit)
    Explanation: Sister planet stands / together with sister stars. / Celebrate the sky.
  • Astronomy Picture of the Day -- Venus and the Sisters

    04/06/2012 9:46:22 AM PDT · by SunkenCiv · 12 replies
    NASA ^ | April 06, 2012 | (see photo credit)
    Explanation: After wandering about as far from the Sun on the sky as Venus can get, the brilliant evening star crossed paths with the Pleiades star cluster earlier this week. The beautiful conjunction was enjoyed by skygazers around the world. Taken on April 2, this celestial group photo captures the view from Portal, Arizona, USA. Also known as the Seven Sisters, even the brighter naked-eye Pleiades stars are seen to be much fainter than Venus. And while Venus and the sisters do look star-crossed, their spiky appearance is the diffraction pattern caused by multiple leaves in the aperture of the...
  • Astronomy Picture of the Day -- Zodiacal Light Panorama

    04/05/2012 8:07:48 PM PDT · by SunkenCiv · 4 replies
    NASA ^ | April 05, 2012 | (see photo credit)
    Explanation: Sweeping from the eastern to western horizon, this 360 degree panorama follows the band of zodiacal light along the solar system's ecliptic plane. Dust scattering sunlight produces the faint zodiacal glow that spans this fundamental coordinate plane of the celestial sphere, corresponding to the apparent yearly path of the Sun through the sky and the plane of Earth's orbit. The fascinating panorama is a mosaic of images taken from dusk to dawn over the course of a single night at two different locations on Mauna Kea. The lights of Hilo, Hawaii are on the eastern (left) horizon, with the...
  • Astronomy Picture of the Day -- Centaurus A

    04/05/2012 8:07:45 PM PDT · by SunkenCiv · 10 replies
    NASA ^ | April 04, 2012 | (see photo credit)
    Explanation: What's the closest active galaxy to planet Earth? That would be Centaurus A, only 11 million light-years distant. Spanning over 60,000 light-years, the peculiar elliptical galaxy is also known as NGC 5128. Forged in a collision of two otherwise normal galaxies, Centaurus A's fantastic jumble of young blue star clusters, pinkish star forming regions, and imposing dark dust lanes are seen here in remarkable detail. The colorful galaxy portrait was recorded under clear Chilean skies at the Cerro Tololo Inter-American Observatory. Near the galaxy's center, left over cosmic debris is steadily being consumed by a central black hole with...