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26/04/2019

Science & Technology - Astronomy picture of the day : Southern Cross to Eta Carinae

2019 April 26
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Southern Cross to Eta Carinae Image Credit & CopyrightCarlos Fairbairn
Explanation: Tracking along the southern Milky Way this beautiful celestial mosaic was recorded under dark Brazilian skies. Spanning some 20 degrees it actually starts with the dark expanse of the Coalsack nebula at the lower left, tucked under an arm of the Southern Cross. That compact constellation is topped by bright yellowish Gamma Crucis, a cool giant star a mere 88 light-years distant. A line from Gamma Crucis through the blue star at the bottom of the cross, Alpha Crucis, points toward the South Celestial Pole. Follow the Milky Way to the right and your gaze will sweep across IC 2948, popularly known as the Running Chicken nebula, before it reaches Eta Carinae and the Carina Nebula near the right edge of the frame. About 200 light-years across, the Carina Nebula is a star forming region much larger than the more northerly stellar nursery the Orion Nebula. The Carina Nebula lies around 7,500 light-years from Earth along the plane of the Milky Way.

25/04/2019

Science & Technology - Astronomy picture of the day : The Shape of the Southern Crab

2019 April 24
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The Shape of the Southern Crab 
Image Credit: NASAESASTScI
Explanation: The symmetric, multi-legged appearance of the Southern Crab Nebula is certainly distinctive. About 7,000 light-years distant toward the southern sky constellation Centaurus, its glowing nested hourglass shapes are produced by the remarkable symbiotic binary star system at its center. The nebula's dramatic stellar duo consists of a hot white dwarf star and cool, pulsating red giant star shedding outer layers that fall onto the smaller, much hotter companion. Embedded in a disk of material, outbursts from the white dwarf cause an outflow of gas driven away both above and below the disk resulting in the bipolar hourglass shapes. The bright central shape is about half a light-year across. This new Hubble Space Telescope image celebrates the 29th anniversary of Hubble's launch on April 24, 1990 on board the Space Shuttle Discovery.

24/04/2019

Science & Technologie - Le monde des requins - Le requin à pointes noires en Indo-Pacifique

Le requin à pointes noires en Indo-Pacifique
Habitant des récifs d'Indo-Pacifique, le requin à pointes noires (Carcharhinus melanopterus) est reconnaissable aux bordures noires à l'extrémité de ses nageoires, notamment ses ailerons et sa queue. Le contraste entre ces taches noires et son dos d'une couleur brun-gris est accentué par une démarcation blanche. Ce requin mesure environ 1,6 m de long.

Pêché pour sa viande, ses ailerons et son huile de foie, il est classé comme espèce quasi-menacée par l'UICN.

© Kydd Pollock CCO

Science & Technologie : Google autorisé à livrer par drone aux Etats-Unis


Google devance Amazon et devient le premier opérateur autorisé à livrer par drone aux Etats-Unis

Une première dans le monde de la livraison par drone. Le 23 avril, l’administration fédérale américaine de l’aviation, la Federal Aviation Administration (FAA) qui certifie que les engins aériens sont aptes – ou non – à voler, a permis à Wing, le drone développé par Google X, d’opérer comme une compagnie aérienne. En obtenant la certification "Air Carrier" de la FAA, Wing devient la première compagnie de livraison par drone à pouvoir livrer des biens à des particuliers.

Résultat : aux Etats-Unis, on pourra bientôt se faire livrer sa pizza Domino’s, son ordonnance médicale depuis le pharmacien du coin ou son smoothie banane-avocat-cresson provenant du coffee-shop le plus en vue de la ville… par drone.

L'Usine Nouvelle - France

Science & Technology - Astronomy picture of the day : Meteors, Comet, and Big Dipper over La Palma

2019 April 23
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Meteors, Comet, and Big Dipper over La Palma Image Credit & Copyright: Vincent Duparc

Explanation: Meteor showers are caused by streams of solid particles, dust size and larger, moving as a group through space. In most cases, the orbits of these meteor streams can be identified with dust expelled from a comet. When the Earth passes through a stream, the particles leave brilliant trails through the night sky as they disintegrate in Earth's atmosphere. The meteor paths are all parallel to each other, but, like train tracks, the effect of perspective causes them to appear to originate from a radiant point in the distance. The featured image composite was taken during January's Quadrantid meteor shower from La Palma, one of Spain's Canary Islands, off the northwest coast of AfricaThe Quadrantids radiant is visible just below the handle of the Big Dipper. A careful eye will also discern the faint green coma of Comet Wirtanen. Tonight is the peak of the modest Lyrid meteor shower, with several meteors per hour visible from dark locations with clear skies.

21/04/2019

Science & Technology - Astronomy picture of the day : Spiral Aurora over Icelandic Divide

2019 April 21
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Spiral Aurora over Icelandic Divide Image Credit & Copyright: Juan Carlos Casado (TWANStarryEarth)
Explanation: Admire the beauty but fear the beast. The beauty is the aurora overhead, here taking the form of great green spiral, seen between picturesque clouds with the bright Moon to the side and stars in the background. The beast is the wave of charged particles that creates the aurora but might, one day, impair civilization. In 1859, following notable auroras seen all across the globe, a pulse of charged particles from a coronal mass ejection (CME) associated with a solar flare impacted Earth's magnetosphere so forcefully that they created the Carrington Event. A relatively direct path between the Sun and the Earth might have been cleared by a preceding CME. What is sure is that the Carrington Event compressed the Earth's magnetic field so violently that currents were created in telegraph wires so great that many wires sparked and gave telegraph operators shocks. Were a Carrington-class event to impact the Earth today, speculation holds that damage might occur to global power grids and electronics on a scale never yet experienced. The featured aurora was imaged in 2016 over Thingvallavatn Lake in Iceland, a lake that partly fills a fault that divides Earth's large Eurasian and North American tectonic plates.

20/04/2019

Science & Technology - Astronomy picture of the day : Falcon Heavy Launch Close Up

2019 April 20
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Falcon Heavy Launch Close Up Image Credit: SpaceX
Explanation: Twenty seven Merlin rocket engines are firing in this close-up of the launch of a Falcon Heavy rocket. Derived from three Falcon 9 first stage rockets with nine Merlin rocket engines each, the Falcon Heavy left NASA's Kennedy Space Center launch pad 39A on April 11. This second launch of a Falcon Heavy rocket carried the Arabsat 6A communications satellite to space. In February of 2018, the first Falcon Heavy launch carried Starman and a Tesla Roadster. Designed to be reusable, both booster stages and the central core returned safely to planet Earth, the boosters to Cape Canaveral Air Force Station landing zones. The core stage landed off shore on autonomous spaceport drone ship Of Course I Still Love You.

ASTRONOMY - Red Sprites and Circular Elves Lightning over Italy

 2025 December 23 Red Sprites and Circular Elves Lightning over Italy Image Credit & Copyright:  Valter Binotto Explanation:  What's...