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#2386
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Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. 2013 April 5 Image Credit & Copyright: P-M Hedén (Clear Skies, TWAN) Explanation: It looks like a double comet, but Comet PanSTARRS (C/2011 L4) is just offering skygazers a Messier moment. Outward bound and fading in this starry scene, the well-photographed comet is remarkably similar in brightness to M31, the Andromeda Galaxy. Tracking through northern skies just below the galaxy, the comet was captured as local midnight approached on April 3. Both comet and galaxy were visible to the eye and are immersed in the faint glow of northern lights as our own Milky Way galaxy arcs over a snowy field near Tänndalen, Sweden. Double star cluster h and chi Persei can be spotted along the Milky Way's arc high above the comet/galaxy pair. Follow the arc to bright Deneb, alpha star of the constellation Cygnus, at the right edge of the frame. Tomorrow's picture: light-weekend Πηγή
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όταν γράφεται η ιστορία της ζωής σου, μην αφήνεις κανέναν να κρατάει την πένα |
#2387
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Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. 2013 April 6 Image Credit: ISS Expedition 2 Crew, Gateway to Astronaut Photography of Earth, NASA Explanation: No sudden, sharp boundary marks the passage of day into night in this gorgeous view of ocean and clouds over our fair planet Earth. Instead, the shadow line or terminator is diffuse and shows the gradual transition to darkness we experience as twilight. With the Sun illuminating the scene from the right, the cloud tops reflect gently reddened sunlight filtered through the dusty troposphere, the lowest layer of the planet's nurturing atmosphere. A clear high altitude layer, visible along the dayside's upper edge, scatters blue sunlight and fades into the blackness of space. This picture actually is a single digital photograph taken in June of 2001 from the International Space Station orbiting at an altitude of 211 nautical miles. Tomorrow's picture: the moon's saturn Πηγή
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όταν γράφεται η ιστορία της ζωής σου, μην αφήνεις κανέναν να κρατάει την πένα |
#2388
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Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. 2013 April 7 Image Credit & Copyright: Jens Hackmann Explanation: Just days after sharing the western evening sky with Venus in 2007, the Moon moved on to Saturn - actually passing in front of the ringed planet Saturn when viewed in skies over Europe, northern Africa, and western Asia. Because the Moon and bright planets wander through the sky near the ecliptic plane, such occultation events are not uncommon, but they are dramatic, especially in telescopic views. For example, in this sharp image Saturn is captured emerging from behind the Moon, giving the illusion that it lies just beyond the Moon's bright edge. Of course, the Moon is a mere 400 thousand kilometers away, compared to Saturn's distance of 1.4 billion kilometers. Taken with a digital camera and 20 inch diameter telescope at the Weikersheim Observatory in southern Germany, the picture is a single exposure adjusted to reduce the difference in brightness between Saturn and the cratered lunar surface. Tomorrow's picture: redshift table Πηγή Σχόλιο : Απίστευτη φωτογραφία !!!
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όταν γράφεται η ιστορία της ζωής σου, μην αφήνεις κανέναν να κρατάει την πένα |
#2389
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Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. 2013 April 8 Image Credit: Sergey V. Pilipenko (LPI, MIPT) Explanation: How far away is "redshift six"? Although humans are inherently familiar with distance and time, what is actually measured for astronomical objects is redshift, a color displacement that depends on exactly how energy density has evolved in our universe. Now since cosmological measurements in recent years have led to a concordance on what energy forms pervade our universe, it is now possible to make a simple table relating observed cosmological redshift, labeled "z", with standard concepts of distance and time, including the extrapolated time since the universe began. One such table is listed above, where redshift z is listed in the first and last columns, while the corresponding universe age in billions of years is listed in the central column. To find the meaning of the rest of the columns, please read the accompanying technical paper. Although stars in our galaxy are effectively at cosmological redshift zero, the most distant supernovae seen occur out past redshift one, which the above chart shows occurred when the universe was approximately half its present age. By contrast, the most distant gamma-ray bursts yet observed occur out past redshift six, occurring when the universe was younger than one billion years old, less than 10 percent of its present age. Tomorrow's picture: ring south Πηγή
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όταν γράφεται η ιστορία της ζωής σου, μην αφήνεις κανέναν να κρατάει την πένα |
#2390
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Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. 2013 April 9 Image Credit: Hubble Legacy Archive, ESA, NASA; Processing - Donald Waid Explanation: It's the dim star, not the bright one, near the center of NGC 3132 that created this odd but beautiful planetary nebula. Nicknamed the Eight-Burst Nebula and the Southern Ring Nebula, the glowing gas originated in the outer layers of a star like our Sun. In this reprocessed color picture, the hot purplish pool of light seen surrounding this binary system is energized by the hot surface of the faint star. Although photographed to explore unusual symmetries, it's the asymmetries that help make this planetary nebula so intriguing. Neither the unusual shape of the surrounding cooler shell nor the structure and placements of the cool filamentary dust lanes running across NGC 3132 are well understood. Follow APOD on: Facebook (Daily) (Sky) (Spanish) or Google Plus (Daily) (River) Tomorrow's picture: open space Πηγή
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όταν γράφεται η ιστορία της ζωής σου, μην αφήνεις κανέναν να κρατάει την πένα |
#2391
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Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. 2013 April 10 Image Credit & Copyright: Chris Hadfield (CSA); Annotation assistance: Vincent Berseth Follow APOD in Spanish: On the web with Observatorio and on Facebook with Universo Tomorrow's picture: darkened city upon the sea Πηγή Σχόλιο : Βλέποντας την πολυπλοκότητα του ISS, σκέφτομαι, πως θα σχολίαζαν την εικόνα αυτή, ο Άρθουρ Κλαρκ και ο Ισαάκ Ασίμοφ....
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όταν γράφεται η ιστορία της ζωής σου, μην αφήνεις κανέναν να κρατάει την πένα |
#2392
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Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. 2013 April 11 Image Credit & Copyright: Photo Thierry Cohen / Courtesy Danziger Gallery, New York Explanation: In a haunting vista you can never see, bright stars and the central Milky Way rise over the dark skyline of metropolitan Pudong in Shanghai, China. Looking east across the Huangpu River, the cityscape includes Pudong's 470 meter tall Oriental Pearl Tower. The night sky stretches from Antares and the stars of Scorpius at the far right, to Altair in Aquila at the left. To create the vision of an unseen reality, part of a series of Darkened Cities, photographer Thierry Cohen has combined a daytime image of the city skyline with an image matched in orientation from a dark sky region at the same latitude, just west of Merzouga, Morocco. The result finds the night sky that hours earlier also arced over Shanghai, but drowned in the lights of a city upon the sea. Tomorrow's picture: Yuri's planet Πηγή
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όταν γράφεται η ιστορία της ζωής σου, μην αφήνεις κανέναν να κρατάει την πένα |
#2393
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Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. 2013 April 12 Image Credit: ISS Expedition 30, NASA Tomorrow's picture: light-weekend Πηγή
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όταν γράφεται η ιστορία της ζωής σου, μην αφήνεις κανέναν να κρατάει την πένα |
#2394
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Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. 2013 April 13 Image Credit: NASA Solar Dynamics Observatory Explanation: This week the Sun gave up its strongest solar flare so far in 2013, accompanied by a coronal mass ejection (CME) headed toward planet Earth. A false-color composite image in extreme ultraviolet light from the Solar Dynamics Observatory captures the moment, recorded on April 11 at 0711 UTC. The flash, a moderate, M6.5 class flare erupting from active region AR 11719, is near the center of the solar disk. Other active regions, areas of intense magnetic fields seen as sunspot groups in visible light, mottle the surface as the solar maximum approaches. Loops and arcs of glowing plasma trace the active regions' magnetic field lines. A massive cloud of energetic, charged particles, the CME will impact the Earth's magnetosphere by this weekend and skywatchers should be on the alert for auroral displays. Tomorrow's picture: crescent father and son Πηγή
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όταν γράφεται η ιστορία της ζωής σου, μην αφήνεις κανέναν να κρατάει την πένα |
#2395
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Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. 2013 April 14 Image Credit: Voyager 2, NASA Explanation: Gliding silently through the outer Solar System, the Voyager 2 spacecraft camera captured Neptune and Triton together in crescent phase in 1989. The elegant picture of the gas giant planet and its cloudy moon was taken from behind just after closest approach. It could not have been taken from Earth because Neptune never shows a crescent phase to sunward Earth. The unusual vantage point also robs Neptune of its familiar blue hue, as sunlight seen from here is scattered forward, and so is reddened like the setting Sun. Neptune is smaller but more massive than Uranus, has several dark rings, and emits more light than it receives from the Sun. Πηγή
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όταν γράφεται η ιστορία της ζωής σου, μην αφήνεις κανέναν να κρατάει την πένα |
#2396
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Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. 2013 April 15 Image Credit & Copyright: Bob Andersson Explanation: Stars are forming in the Soul of the Queen of Aethopia. More specifically, a large star forming region called the Soul Nebula can be found in the direction of the constellation Cassiopeia, who Greek mythology credits as the vain wife of a King who long ago ruled lands surrounding the upper Nile river. The Soul Nebula houses several open clusters of stars, a large radio source known as W5, and huge evacuated bubbles formed by the winds of young massive stars. Located about 6,500 light years away, the Soul Nebula spans about 100 light years and is usually imaged next to its celestial neighbor the Heart Nebula (IC 1805). The above image appears mostly red due to the emission of a specific color of light emitted by excited hydrogen gas. Follow APOD on: Facebook (Daily) (Sky) (Spanish) or Google Plus (Daily) (River) Tomorrow's picture: loopy spiral Πηγή
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όταν γράφεται η ιστορία της ζωής σου, μην αφήνεις κανέναν να κρατάει την πένα |
#2397
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Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. 2013 April 16 Image Credit & Copyright: Bernard Miller Explanation: One of the brightest galaxies in planet Earth's sky is similar in size to our Milky Way Galaxy: big, beautiful M81. This grand spiral galaxy lies 11.8 million light-years away toward the northern constellation of the Great Bear (Ursa Major). The deep image of the region reveals details in the bright yellow core, but at the same time follows fainter features along the galaxy's gorgeous blue spiral arms and sweeping dust lanes. It also follows the expansive, arcing feature, known as Arp's loop, that seems to rise from the galaxy's disk at the upper right. Studied in the 1960s, Arp's loop has been thought to be a tidal tail, material pulled out of M81 by gravitational interaction with its large neighboring galaxy M82. But a subsequent investigation demonstrates that at least some of Arp's loop likely lies within our own galaxy. The loop's colors in visible and infrared light match the colors of pervasive clouds of dust, relatively unexplored galactic cirrus only a few hundred light-years above the plane of the Milky Way. Along with the Milky Way's stars, the dust clouds lie in the foreground of this remarkable view. M81's dwarf companion galaxy, Holmberg IX, can be seen just above the large spiral. On the sky, this image spans about 0.5 degrees, about the size of the Full Moon. Tomorrow's picture: open space Πηγή
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όταν γράφεται η ιστορία της ζωής σου, μην αφήνεις κανέναν να κρατάει την πένα |
#2398
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Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. 2013 April 17 Image Credit & Copyright: Ben Canales Explanation: What kind of cloud is next to that mountain? A lenticular. This type of cloud forms in air that passes over a mountain, rises up again, and cools past the dew point -- so what molecular water carried in the air condenses into droplets. The layered nature of some lenticular clouds may make them appear, to some, as large alien spaceships. In this case, the mountain pictured is Mt. Hood located in Oregon, USA. Lenticular clouds can only form when conditions are right -- for example this is first time this astrophotographer has seen a lenticular cloud at night near Mt. Hood. The above image was taken in mid-March about two hours before dawn. Tomorrow's picture: star factory M17 Πηγή Σχόλιο : Εντυπωσιακή φωτογραφία!!!
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όταν γράφεται η ιστορία της ζωής σου, μην αφήνεις κανέναν να κρατάει την πένα |
#2399
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Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. 2013 April 18 Image Credit: Subaru Telescope (NAOJ), Hubble Space Telescope, Color data: Wolfgang Promper, Processing: Robert Gendler Explanation: Sculpted by stellar winds and radiation, the star factory known as Messier 17 lies some 5,500 light-years away in the nebula-rich constellation Sagittarius. At that distance, this degree wide field of view spans almost 100 light-years. The sharp, composite, color image utilizing data from space and ground based telescopes, follows faint details of the region's gas and dust clouds against a backdrop of central Milky Way stars. Stellar winds and energetic light from hot, massive stars formed from M17's stock of cosmic gas and dust have slowly carved away at the remaining interstellar material producing the cavernous appearance and undulating shapes. M17 is also known as the Omega Nebula or the Swan Nebula. Tomorrow's picture: exploring the suburbs Πηγή
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όταν γράφεται η ιστορία της ζωής σου, μην αφήνεις κανέναν να κρατάει την πένα |
#2400
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Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. 2013 April 19 Image Credit & Copyright: John Davis Explanation: This skyscape finds an esthetic balance of interstellar dust and gas residing in the suburbs of the nebula rich constellation of Orion. Reflecting the light of bright star Rigel, Beta Orionis, the jutting, bluish chin of the Witch Head Nebula is at the upper left. Whiskers tracing the red glow of hydrogen gas ionized by ultraviolet starlight seem to connect that infamous visage with smaller nebulae, like dusty reflection nebula NGC 1788 at the right. Strong winds from Orion's bright stars have also shaped NGC 1788, and likely triggered the formation of the young stars within. Appropriate for its location, NGC 1788 looks to some like a cosmic bat. The scene spans about 3 degrees on the sky or 6 full Moons. Tomorrow's picture: not so dark Πηγή
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όταν γράφεται η ιστορία της ζωής σου, μην αφήνεις κανέναν να κρατάει την πένα |
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