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12/11/2019

Musica - Video - Monteverdi : "Lamento della Ninfa"

"Lamento della Ninfa"

Science & Technology - Astronomy picture of the day : NGC 3717 : A Nearly Sideways Spiral Galaxy

2019 November 12
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NGC 3717: A Nearly Sideways Spiral Galaxy 
Image Credit: ESA/Hubble & NASAProcessing: D. Rosario
Explanation: Some spiral galaxies are seen nearly sideways. Most bright stars in spiral galaxies swirl around the center in a disk, and seen from the side, this disk can be appear quite thin. Some spiral galaxies appear even thinner thanNGC 3717, which is actually seen tilted just a bit. Spiral galaxies form disks because the original gas collided with itself and cooled as it fell inward. Planets may orbit in disks for similar reasons. The featured image by the Hubble Space Telescope shows a light-colored central bulge composed of older stars beyond filaments of orbiting dark brown dustNGC 3717 spans about 100,000 light years and lies about 60 million light years away toward the constellation of the Water Snake (Hydra).

11/11/2019

Science & Technology - Astronomy picture of the day : Lunar Craters Langrenus and Petavius

2019 November 11
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Lunar Craters Langrenus and Petavius 
Image Credit & Copyright: Eduardo Schaberger Poupeau
Explanation: The history of the Moon is partly written in its craters. Pictured here is a lunar panorama taken from Earth featuring the large craters Langrenus, toward the left, and Petavius, toward the right. The craters formed in separate impactsLangrenus spans about 130 km, has a terraced rim, and sports a central peak rising about 3 km. Petavius is slightly larger with a 180 km diameter and has a distinctive fracture that runs out from its center. Although it is known that Petravius crater is about 3.9 billion years old, the origin of its large fracture is unknown. The craters are best visible a few days after a new Moon, when shadows most greatly accentuate vertical walls and hills. Thefeatured image is a composite of the best of thousands of high-resolution, infrared, video images taken through a small telescope. Although mountains on Earth will likely erode into soil over a billion years, lunar craters Langrenus and Petavius will likely survive many billions more years, possibly until the Sun expands and engulfs both the Earth and Moon.

10/11/2019

Science & Technology - Astronomy picture of the day : A Mercury Transit Sequence

2019 November 10
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A Mercury Transit Sequence 
Image Credit & Copyright: Dominique Dierick
Explanation: Tomorrow -- Monday -- Mercury will cross the face of the Sun, as seen from Earth. Called a transit, the last time this happened was in 2016. Because the plane of Mercury's orbit is not exactly coincident with the plane of Earth's orbit, Mercury usually appears to pass over or under the Sun. The featured time-lapse sequence, superimposed on a single frame, was taken from a balcony in Belgium shows the entire transit of 2003 May 7. That solar crossing lasted over five hours, so that the above 23 images were taken roughly 15 minutes apart. The north pole of the Sun, the Earth's orbit, and Mercury's orbit, although all different, all occur in directions slightly above the left of the image. Near the center and on the far right, sunspots are visible. After Monday, the next transit of Mercury will occur in 2032.

09/11/2019

Sciece & Technology - Astronomy picture of the day : Saturn the Giant

2019 November 9
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Saturn the Giant 
Image Credit: NASA
Explanation: On May 25, 1961 U.S. president John Kennedy announced the goal of landing astronauts on the Moon by the end of the decade. By November 9, 1967 this Saturn V rocket was ready for launch and the first full test of its capabilities on the Apollo 4 mission. Its development directed by rocket pioneer Wernher Von Braun, the three stage Saturn V stood over 36 stories tall. It had a cluster of five first stage engines fueled by liquid oxygen and kerosene which together were capable of producing 7.9 million pounds of thrust. Giant Saturn V rockets ultimately hurled nine Apollo missions to the Moon and back again with six landing on the lunar surface. The first landing mission, Apollo 11, achieved Kennedy's goal on July 20, 1969.

07/11/2019

Science & Technology - Astronomy picture of the day - Messier 45: The Daughters of Atlas and Pleione

2019 November 7
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Messier 45: The Daughters of Atlas and Pleione 
Image Credit & Copyright: Adam BlockSteward Observatory, University of Arizona
Explanation: Hurtling through a cosmic dust cloud a mere 400 light-years away, the lovely Pleiades or Seven Sisters open star cluster is well-known for its striking blue reflection nebulae. It lies in the night sky toward the constellation Taurus and the Orion Arm of our Milky Way Galaxy. The sister stars and cosmic dust cloud are not related though, they just happen to be passing through the same region of space. Known since antiquity as a compact grouping of stars, Galileo first sketched the star cluster viewed through his telescope with stars too faint to be seen by eye. Charles Messier recorded the position of the cluster as the 45th entry in his famous catalog of things which are not comets. In Greek myth, the Pleiades were seven daughters of the astronomical Titan Atlas and sea-nymph Pleione. Their parents names are included in the cluster's nine brightest stars. This deep and wide telescopic image spans over 20 light-years across the Pleides star cluster.

06/11/2019

Science & Technology - Astronomy picture of the day : 21st Century M101

2019 November 6
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21st Century M101 
Image Credit: NASAESACXCJPL - CaltechSTScI
Explanation: One of the last entries in Charles Messier's famous catalog, big, beautiful spiral galaxy M101 is definitely not one of the least. About 170,000 light-years across, this galaxy is enormous, almost twice the size of our own Milky Way Galaxy. M101 was also one of the original spiral nebulae observed with Lord Rosse's large 19th century telescope, the Leviathan of Parsonstown. In contrast, this multiwavelength view of the large island universe is a composite of images recorded by space-based telescopes in the 21st century. Color coded from X-rays to infrared wavelengths (high to low energies), the image data was taken from the Chandra X-ray Observatory (purple), theGalaxy Evolution Explorer (blue), Hubble Space Telescope(yellow), and the Spitzer Space Telescope(red). While the X-ray data trace the location of multimillion degree gas around M101's exploded stars and neutron star and black hole binary star systems, the lower energy data follow the stars and dust that define M101's grand spiral arms. Also known as the Pinwheel Galaxy, M101 lies within the boundaries of the northern constellation Ursa Major, about 25 million light-years away.

05/11/2019

Science & Technology - Astronomy picture of the day : Spiral Galaxies Spinning Super-Fast

2019 November 5
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Spiral Galaxies Spinning Super-Fast 
Image Credit: Top row: NASAESAHubble, P. Ogle & J. DePasquale (STScI);
Bottom row: SDSS, P. Ogle & J. DePasquale (STScI)
Explanation: Why are these galaxies spinning so fast? If you estimated each spiral's mass by how much light it emits, their fast rotations should break them apart. The leading hypothesis as to why these galaxies don't break apart isdark matter -- mass so dark we can't see it. But these galaxies are even out-spinning this break-up limit -- they are the fastest rotating disk galaxies known. It is therefore further hypothesized that their dark matter halos are so massive -- and their spins so fast -- that it is harder for them to form stars than regular spirals. If so, then these galaxies may be among the most massive spirals possible. Further study of surprising super-spirals like these will continue, likely including observations taken by NASA's James Webb Space Telescope scheduled for launch in 2021.

04/11/2019

Science & Technology - Astronomy picture of the day : Near the Center of the Lagoon Nebula

2019 November 4
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Near the Center of the Lagoon Nebula 
Image Credit & Copyright: Zhuoqun Wu, Chilescope
Explanation: Stars are battling gas and dust in the Lagoon Nebula but the photographers are winning. Also known as M8, this photogenic nebula is visible even without binoculars towards the constellation of the Archer (Sagittarius). The energetic processes of star formation create not only the colors but the chaos. The glowing gas results from high-energy starlight striking interstellar hydrogen gas and trace amounts of sulfur, and oxygen gases. The dark dustfilaments that lace M8 were created in the atmospheres of cool giant stars and in the debris from supernovae explosions. The light from M8 we see today left about 5,000 years ago. Light takes about 50 years to cross this section of

03/11/2019

Science & Technology - Astronomy picture of the day : Daphnis and the Rings of Saturn

2019 November 3
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Daphnis and the Rings of Saturn 
Image Credit: NASAJPL-CaltechSpace Science InstituteCassini
Explanation: What's happening to the rings of Saturn? A little moon making big waves. The moon is 8-kilometer Daphnis and it is making waves in the Keeler Gap of Saturn's rings using just its gravity -- as it bobs up and down, in and out. The featured image is a colored and more detailed version of a previously released images taken in 2017 by the robotic Cassini spacecraft during one of its Grand Finale orbitsDaphnis can be seen on the far right, sporting ridges likely accumulated from ring particlesDaphnis was discovered in Cassini images in 2005 and raised mounds of ring particles so high in 2009 -- during Saturn's equinox when the ring plane pointed directly at the Sun -- that they cast notable shadows.

ASTRONOMIE - Les plus beaux astres de la Voie Lactée - Vénus - l’étoile du Berger

En raison de caractéristiques très proches de la Terre en matière de taille et de géologie , Vénus est souvent décrite comme sa sœur jumel...