Autor Tópico: APOD DO DIA  (Lida 12653 vezes)

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Offline ahlberto

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Re: APOD DO DIA
« Responder #60 em: Abril 10, 2009, 12:23:30 am »
Unusual Dusty Galaxy NGC 7049
Credit: NASA, ESA and W. Harris (McMaster University)
Explanation: How was this unusual looking galaxy created? No one is sure, especially since spiral galaxy NGC 7049 looks so strange. NGC 7049's striking appearance is primarily due to an unusually prominent dust ring seen mostly in silhouette. The opaque ring is much darker than the din of millions of bright stars glowing behind it. Besides the dark dust, NGC 7049 appears similar to a smooth elliptical galaxy, although featuring surprisingly few globular star clusters. NGC 7049 is pictured above as imaged recently by the Hubble Space Telescope. The bright star near the top of NGC 7049 is an unrelated foreground star in our own Galaxy. Not visible here is an unusual central polar ring of gas circling out of the plane near the galaxy's center. Since NGC 7049 is the brightest galaxy in its cluster of galaxies, its formation might be fostered by several prominent and recent galaxy collisions. NGC 7049 spans about 150 thousand light years and lies about 100 million light years away toward the constellation of Indus.
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Offline ahlberto

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Re: APOD DO DIA
« Responder #61 em: Abril 11, 2009, 01:40:42 pm »
ISS and Astronaut
Credit & Copyright: Ralf Vandebergh
Explanation: These two frames, taken with a video camera and a telescope, reveal remarkable details of the International Space Station (ISS) orbiting some 350 kilometers above planet Earth. Recorded during last month's visit by the crew of shuttle orbiter Discovery on mission STS-119, the pictures show extended solar arrays glinting in bright sunlight against a dark sky. They also likely capture the blurred image of a spacewalking astronaut during the mission's EVA-2 (Extravehicular Activity-2)! The astronaut is installing equipment along one of the station's truss assemblies. Astronomer Ralf Vandebergh, who often images the ISS during its favorable passes through Dutch skies, comments that no other bright ISS structures occupy the position indicated in the inset, and that a reflective, white-suited astronaut would be visible against the truss and correspond to the bright blur. Vandebergh notes that the timing and location further suggest the spacewalker is STS-119 astronaut Joseph Acaba.
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Offline ahlberto

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Re: APOD DO DIA
« Responder #62 em: Abril 11, 2009, 10:34:32 pm »
The Big Picture
Credit & Copyright: Dennis di Cicco (TWAN) & Sean Walker, Skyandtelescope.com
Explanation: Intricate, glowing nebulae that shine in planet Earth's night sky are beautiful to look at in deep images made with telescopes and sensitive cameras. But they are faint and otherwise invisible to the naked-eye. That makes their relative location and extent on the sky difficult to appreciate. So, consider this impressive composite image of a wide region of the northern winter sky. With a total exposure time of 40 hours, the painstaking mosaic presents a nebula-rich expanse known as the Orion-Eridanus Superbubble above a house in suburban Boston, USA. Within the wide and deep view are nebulae more often seen in narrower views, including the Great Orion Nebula, the Rosette Nebula, the Seagull Nebula, the California Nebula, and Barnard's Loop. The familiar constellation of Orion itself is just above the foreground house. Brightest star Sirius is left of the roof, and the recognizable Pleiades star cluster is above the tree at the right. A version of the big picture that includes simple constellation guidelines is available here.
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Offline ahlberto

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Re: APOD DO DIA
« Responder #63 em: Abril 14, 2009, 08:25:05 pm »
M101: The Pinwheel Galaxy
Credit & Copyright: Adam Block, Mt. Lemmon SkyCenter, U. Arizona
Explanation: Why do many galaxies appear as spirals? A striking example is M101, shown above, whose relatively close distance of about 27 million light years allows it to be studied in some detail. Recent evidence indicates that a close gravitational interaction with a neighboring galaxy created waves of high mass and condensed gas which continue to orbit the galaxy center. These waves compress existing gas and cause star formation. One result is that M101, also called the Pinwheel Galaxy, has several extremely bright star-forming regions (called HII regions) spread across its spiral arms. M101 is so large that its immense gravity distorts smaller nearby galaxies.
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Re: APOD DO DIA
« Responder #64 em: Abril 17, 2009, 08:57:40 pm »
Jagged Shadows May Indicate Saturn Ring Particles
Credit: NASA, JPL, Space Science Institute
Explanation: What's causing unusual jagged shadows on Saturn's rings? No one is yet sure. As Saturn nears equinox, its rings increasingly show only their thin edge to the Earth and Sun. As a result, Saturn's moons now commonly cast long shadows onto the rings. An example of this is the elongated vertical shadow of Mimas seen on the above right. The series of shorter, jagged shadows that run diagonally, however, are more unusual. Now Saturn's rings have been known to be made of particles for hundreds of years, but these particles have so far escaped direct imaging. It is therefore particularly exciting that a preliminary hypothesis holds that these jagged shadows are silhouettes of transient groups of ring particles temporarily held close by their own gravity. Future work will surely continue, as the robotic Cassini spacecraft orbiting Saturn that took the above image will continue to photograph Saturn's magnificent rings right through Saturn's equinox this August.
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Offline ahlberto

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Re: APOD DO DIA
« Responder #65 em: Abril 17, 2009, 09:00:35 pm »
Castle and Full Moon
Credit & Copyright: Paolo Tanga, Observatoire de la Cote d'Azur
Explanation: Clouds couldn't hide this bright Full Moon as it rose last week over the medieval castle of Tourrette-Levens near Nice, France. Exactly full on April 9 at 1456 UT, it followed the March equinox, making it the first Full Moon of spring in the north and autumn in the southern hemisphere. Known as the Easter Moon, it fixes the date for the Christian celebration of Easter on the first Sunday after the first Full Moon of northern spring. Also called the Grass Moon or Egg Moon in the north, in the southern hemisphere, following the autumnal equinox, this Full Moon shines throughout the night as a Hunter's Moon.
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Offline ahlberto

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Re: APOD DO DIA
« Responder #66 em: Abril 17, 2009, 09:02:55 pm »
Medieval Astronomy from Melk Abbey
Credit: Paul Beck (Univ. Vienna), Georg Zotti (Vienna Inst. Arch. Science)
Copyright: Library of Melk Abbey, Frag. 229
Explanation: Discovered by accident, this manuscript page provides graphical insight to astronomy in medieval times, before the Renaissance and the influence of Nicolaus Copernicus, Tycho de Brahe, Johannes Kepler, and Galileo. The intriguing page is from lecture notes on astronomy compiled by the monk Magister Wolfgang de Styria before the year 1490 at Melk Abbey in Austria. The top panels clearly illustrate the necessary geometry for a lunar (left) and solar eclipse in the Earth-centered Ptolemaic system. At lower left is a diagram of the Ptolemaic view of the solar system and at the lower right is a chart to calculate the date of Easter Sunday in the Julian calendar. Text at the upper right explains the movement of the planets according to the Ptolemaic system. The actual manuscript page is on view at historic Melk Abbey as part of a special exhibition during the International Year of Astronomy.
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Offline ahlberto

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Re: APOD DO DIA
« Responder #67 em: Abril 19, 2009, 09:22:44 pm »
NGC 1333 Stardust
Credit & Copyright: Stephen Leshin
Explanation: NGC 1333 is seen in visible light as a reflection nebula, dominated by bluish hues characteristic of starlight reflected by dust. A mere 1,000 light-years distant toward the heroic constellation Perseus, it lies at the edge of a large, star-forming molecular cloud. This striking close-up view spans about 4 light-years at the estimated distance of NGC 1313. It shows details of the dusty region along with hints of contrasting emission in red jets and glowing gas from recently formed stars. In fact, NGC 1333 contains hundreds of stars less than a million years old, most still hidden from optical telescopes by the pervasive stardust. The chaotic environment may be similar to one in which our own Sun formed over 4.5 billion years ago
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Offline ahlberto

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Re: APOD DO DIA
« Responder #68 em: Abril 19, 2009, 09:24:11 pm »
The View Near a Black Hole
Drawing Credit: April Hobart, CXC
Explanation: In the center of a swirling whirlpool of hot gas is likely a beast that has never been seen directly: a black hole. Studies of the bright light emitted by the swirling gas frequently indicate not only that a black hole is present, but also likely attributes. The gas surrounding GRO J1655-40, for example, has been found to display an unusual flickering at a rate of 450 times a second. Given a previous mass estimate for the central object of seven times the mass of our Sun, the rate of the fast flickering can be explained by a black hole that is rotating very rapidly. What physical mechanisms actually cause the flickering -- and a slower quasi-periodic oscillation (QPO) -- in accretion disks surrounding black holes and neutron stars remains a topic of much research.
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Offline ahlberto

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Re: APOD DO DIA
« Responder #69 em: Abril 20, 2009, 04:16:17 pm »
Flowing Barchan Sand Dunes on Mars
Credit: HiRISE, MRO, LPL (U. Arizona), NASA
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, where the season is 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 barchans, and are the interplanetary cousins of similar Earth-based sand forms. Barchans can move intact downwind and can even appear to pass through each other. Over the past few weeks, winds on southern Mars have been kicking up dust and are being watched to see if they escalate into another of Mars' famous planet-scale sand storms.
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Offline ahlberto

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Re: APOD DO DIA
« Responder #70 em: Abril 29, 2009, 12:01:11 am »
NGC 4565: Galaxy on the Edge
Credit & Copyright: Roth Ritter (Dark Atmospheres)
Explanation: Is our Galaxy this thin? We believe so. Magnificent spiral galaxy NGC 4565 is likely similar to our own spiral galaxy, but viewed edge-on from far away. Also known as the Needle Galaxy for its narrow profile, bright NGC 4565 is a stop on many telescopic tours of the northern sky as it lies in the faint but well-groomed constellation Coma Berenices. This sharp color image reveals the galaxy's bulging central core dominated by light from a population of older, yellowish stars. The core is dramatically cut by obscuring dust lanes which lace NGC 4565's thin galactic plane. NGC 4565 lies about 30 million light-years distant and spans over 100,000 light-years in diameter. Visible through a small telescope, some sky enthusiasts consider NGC 4565 to be a prominent celestial masterpiece Messier missed.
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Offline ahlberto

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Re: APOD DO DIA
« Responder #71 em: Abril 30, 2009, 02:38:18 pm »
GRB 090423: The Farthest Explosion Yet Measured
Credit: Gemini Observatory / NSF / AURA, D. Fox & A. Cucchiara (Penn State U.), and E. Berger (Harvard Univ.)
Explanation: An explosion so powerful it was seen clear across the visible universe was recorded in gamma-radiation last week by NASA's orbiting Swift Observatory. Farther than any known galaxy, quasar, or optical supernova, the gamma-ray burst recorded last week was clocked at redshift 8.2, making it the farthest explosion of any type yet detected. Occurring only 630 million years after the Big Bang, GRB 090423 detonated so early that astronomers had no direct evidence that anything explodable even existed back then. The faint infrared afterglow of GRB 090423 was recovered by large ground telescopes within minutes of being discovered. The afterglow is circled in the above picture taken by the large Gemini North Telescope in Hawaii, USA. An exciting possibility is that this gamma-ray burst occurred in one of the very first generation of stars and announced the birth of an early black hole. Surely, GRB 090423 provides unique data from a relatively unexplored epoch in our universe and a distant beacon from which the intervening universe can be studied.
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Offline ahlberto

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Re: APOD DO DIA
« Responder #72 em: Abril 30, 2009, 02:40:16 pm »
Framed by Clouds
Credit & Copyright: Pete Lawrence (Digital-Astronomy)
Explanation: Last Sunday's fading evening twilight featured a young crescent Moon along the western horizon. The young Moon also shared the sky with the lovely Pleiades star cluster and wandering planet Mercury. Framed by clouds in this serene skyscape from Selsey, UK, a similar twilight scene was visible around the globe. Emerging from the cloud bank below the Pleiades, the narrow sunlit lunar crescent is overexposed. Still, the Moon's dim night side is impressively clear, illuminated by earthshine. Bright, innermost planet Mercury lies near the bottom of the field. Mercury will remain near the Pleiades, low in the west after sunset over the coming days, an ongoing conjunction of planet and star cluster that will offer skygazers some excellent binocular views.
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Offline ahlberto

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Re: APOD DO DIA
« Responder #73 em: Maio 05, 2009, 08:46:08 am »
Titan Beyond the Rings
Credit: Cassini Imaging Team, ISS, JPL, ESA, NASA
Explanation: When orbiting Saturn, be sure to watch for breathtaking superpositions of moons and rings. One such picturesque vista was visible recently to the robot Cassini spacecraft now orbiting Saturn. In 2006 April, Cassini captured Saturn's A and F rings stretching in front of cloud-shrouded Titan. Near the rings and appearing just above Titan was Epimetheus, a moon which orbits just outside the F ring. The dark space in the A ring is called the Encke Gap, although several thin knotted ringlets and even the small moon Pan orbit there. Cassini and curious Earthlings await the coming Saturnian equinox this summer when the ring plane will point directly at the Sun. Mysterious spokes and telling shadows are expected to become visible that might give away more clues about the nature of Saturn's ring particles.
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Re: APOD DO DIA
« Responder #74 em: Maio 18, 2009, 09:04:27 am »
Moon Rays Over Thurso Castle
Credit & Copyright: Stewart Watt
Explanation: What's happening over that castle? While waiting for the Moon to rise last month in Thurso, Scotland, amateur astrophotographer Stewart Watt took a three minute exposure of the background stars. The above image was the surprising result. Patchy clouds in front of the rising moon created crepuscular rays streaming across the night sky in spectacular fashion. In the foreground is a stone tower from Thurso Castle, a 12th century fortress augmented in the 17th century. Above the crepuscular moon rays are stars, many from the constellation of the Lion (Leo). Visible to the right of the tower is the planet Saturn.
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