Science & Technology - Astronomy picture of the day : Dark Skies: Turn on the Night

2019 May 16
Dark Skies: Turn on the Night 
Image Credit & Copyright: Jeff Dai (TWAN)

Explanation: Have you ever experienced a really dark night sky? One common and amazing feature is the glowing band of our Milky Way galaxy stretching from horizon to horizon. If you live in or near a big city, though, you might not know this because city lights reflecting off the Earth's atmosphere could only allow you to see the Moon and a few stars. Today, however, being UNESCO's International Day of Light, the International Astronomical Union is asking people to Turn on the Night by trying to better understand, and in the future better reduce, light pollution. You can practice even now by going to the main APOD website at NASA and hovering your cursor over the Before image. TheAfter picture that comes up is a panorama of four exposures taken with the same camera and from the same location, showing what happened recently in China when people in Kaihua County decided to turn down many of their lights. Visible in the Before picture are the stars Sirius (left of center) and Betelgeuse, while visible in the After picture are thousands of stars with the arching band of our Milky Way Galaxy. Humanity has lived for millennia under a dark night sky, and connecting to it has importance for both natural and cultural heritage.

Science & Technology - Astronomy picture of the day : Young Star Cluster Trumpler 14 from Hubble

2019 May 14
Young Star Cluster Trumpler 14 from Hubble Image Credit: NASA, ESA, and J. Maíz Apellániz (IoAoA Spain); Acknowledgment: N. Smith (U. Arizona)

Explanation: Why does star cluster Trumpler 14 have so many bright stars? Because it is so young. Many cluster stars have formed only in the past 5 million years and are so hot they emit detectable X-rays. In older star clusters, most stars this young have already died -- typically exploding in a supernova -- leaving behind stars that are fainter and redder. Trumpler 14 spans about 40 light years and lies about 9,000 light years away on the edge of the famous Carina Nebula. A discerning eye can spot two unusual objects in this detailed 2006 image of Trumpler 14 by the Hubble Space Telescope. First, a dark cloud just left of center may be a planetary system trying to form before being destroyed by the energetic winds of Trumpler 14's massive stars. Second is the arc at the bottom left, which one hypothesis holds is the supersonic shock wave of a fast star ejected 100,000 years ago from a completely different star cluster.

Science & Technology - Astronomy picture of the day : Ash and Lightning above an Icelandic Volcano

2019 May 12
Ash and Lightning above an Icelandic Volcano 
Image Credit & Copyright: Sigurður Stefnisson

Explanation: Why did a picturesque volcanic eruption in Iceland create so much ash? Although the large ash plume was not unparalleled in its abundance, its location was particularly noticeable because it drifted across such well-populated areas. The Eyjafjallajökull volcano in southern Iceland began erupting on 2010 March 20, with a second eruption starting under the center of a small glacier on 2010 April 14. Neither eruption was unusually powerful. The second eruption, however, melted a large amount of glacial ice which then cooled and fragmented lava into gritty glass particles that were carried up with the rising volcanic plume. Pictured here during the second eruption, lightning boltsilluminate ash pouring out of the Eyjafjallajökull volcano.

Science & Technology - Astronomy picture of the day : Way Halley Dust and Milky

2019 May 10
Way Halley Dust and Milky 
Image Credit & Copyright: Gang Li

Explanation: Grains of cosmic dust streaked through the mostly moonless night skies of May 7. Swept up as planet Earth plowed through the debris streams left behind by periodic Comet Halley, the annual meteor shower is known as the Eta Aquarids. Though it was made about a day after the shower's predicted maximum, this composite image still captures 20 meteors in exposures taken over a 2 hour period, registered on a background exposure of the sky. The meteor trails point back to the shower radiant near eponymous faint star Eta Aquarii close to the horizon, seen from 100 kilometers south of Sydney Australia. Known for speed, Eta Aquarid meteors move fast, entering the atmosphere at about 66 kilometers per second. Brilliant Jupiter shines near the central bulge of the Milky Way high above the horizon. The Southern Cross is just tucked in to the upper right corner of the frame.

Science & Technologie - Aeronautique - Vidéo : En Russie, un avion en flammes fait plus de 40 morts

Les images de ce Sukhoi SSJ100 en feu sur l’aéroport Sheremetyevo de Moscou (Russie) hier, dimanche 5 mai, sont impressionnantes. Sur cette vidéo que nous n’avons pas pu authentifier, on voit l’avion d’Aeroflot rebondir une première fois sur la piste puis toucher de nouveau la piste violemment avant de s’embraser, glisser sur plusieurs dizaines de mètres avant de s’immobiliser. L’un des passagers a filmé la scène avec son téléphone portable. Le Sukhoi SSJ100 qui venait de décoller de Moscou à destination de Mourmansk avait demandé à revenir se poser en urgence suite à un problème technique. Une enquête a été ouverte par le bureau russe MAK. 

Le Sukhoi SSJ 100 est un avion monocouloir bimoteur d'une capacité de 75 à 90 sièges qui a été mis en service en 2011. A son lancement, cet avion a rencontré plusieurs problèmes techniques. Le crash d'un Sukhoi SSJ100 en mai 2012, qui avait côuté la vie aux 45 occupants, était dû à une erreur humaine. L'avion avait percuté une montagne lors d'un vol de démonstration. 

Aeroflot est la compagnie aérienne nationale russe dont le siège est à Moscou. Elle opère une flotte d'Airbus et de Boeing moyen et long-courriers et des SSJ100.

Aeronews

Science & Technologie - Santé/Médecine - Cancer :Agiter le sang pour mieux soigner

Pour détruire des cellules cancéreuses, les chercheurs pensent depuis longtemps à utiliser des nanoparticules. Mais l’un des problèmes est de parvenir à les amener jusqu’à leur cible. Une équipe internationale propose une stratégie pour faciliter le passage de ces vecteurs du sang vers les cellules cancéreuses : agiter le fluide de manière à augmenter la diffusion, comme le fait une cuiller dans un thé. Soit en faisant tourner une petite spirale grâce à un champ magnétique, soit en faisant tourner la tête de plusieurs bactéries magnétostatiques. Dans ce cas, après la thérapie, les bactéries sont détruites par des antibiotiques spécifiques ou par surchauffage. Les essais concluants ont été faits dans des canaux plastiques microscopiques et les chercheurs espèrent passer bientôt à des modèles in vivo et des nanoparticules porteuses de principes actifs anticancéreux.

Le Monde Santé - France

Science & Technology - Astronomy picture of the day : Jupiter Marble from Juno

2019 May 8
Jupiter Marble from Juno 
Image Credit: NASA/JPL-Caltech/SwRI/MSSS; Processing: Kevin M. Gill

Explanation: What does Jupiter look like up close? Most images of Jupiter are taken from far away, either from Earth or from a great enough distance that nearly half the planet is visible. This shot, though, was composed from images taken relatively close in, where less than half of the planet was visible. From here, Jupiter still appears spherical but perspective distortion now makes it look more like a marble. Visible on Jupiter's cloud tops are a prominent darkhorizontal belt containing a white oval cloud, and a white zone cloud, both of which circle the planet. The Great Red Spot looms on the upper right. The featured image was taken by the robotic Juno spacecraft in February during its 17th close pass of our Solar System's largest planet. Juno's mission, now extended into 2021, is to study Jupiter in new ways. Juno's data has already enabled discoveries that include Jupiter's magnetic field being surprisingly lumpy, and that some of Jupiter's cloud systems run about 3,000 kilometers into the planet.

Science & Technology - Astronomy picture of the day : The Great Nebula in Carina

2019 May 7
The Great Nebula in Carina 
Image Credit & Copyright: Dieter Willasch (Astro-Cabinet)

Explanation: What's happening in the center of the Carina Nebula? Stars are forming, dying, and leaving an impressive tapestry of dark dusty filaments. The entire Carina Nebula, cataloged as NGC 3372, spans over 300 light yearsand lies about 8,500 light-years away in the constellation of Carina. The nebula is composed predominantly of hydrogen gas, which emits the pervasive red glow seen in this highly detailed featured image. The blue glow in the center is created by a trace amount of glowing oxygen. Young and massive stars located in the nebula's center expel dust when they explode in supernovae. Eta Carinae, the most energetic star in the nebula's center, was one of the brightest stars in the sky in the 1830s, but then faded dramatically.

Science & Technology - Astronomy picture of the day : Virtual Flyby of the Whirlpool Galaxy

2019 May 6
Virtual Flyby of the Whirlpool Galaxy 
Video Credit: F. Summers, J. DePasquale, and D. Player (STScI); Music: Into the Wormhole (Jingle Punks via Youtube)

Explanation: What would it look like to fly over a spiral galaxy? To help visualize this, astronomers and animators at the Space Telescope Science Institute computed a virtual flyby of the Whirlpool Galaxy (M51) using data and images from the Hubble Space Telescope. At only 25 million light years distant and fully 50 thousand light years across, the Whirlpool is one of the brightest and most picturesque galaxies on the sky. Visible during the virtual flyby are spiral arms dominated by young blue stars, older lighter-colored stars, dark lanes of dust, and bright red emission nebulae. Many galaxies far in the distance can be seen right through M51. The visualization should be considered a time-lapse, because otherwise the speed of the virtual camera would need to be very near the speed of light.

Science & Technologie - Aeronautique - Video : Rarissime B-2 Spirit pendant son ravitaillement en vol

Il n’en existe que 21 et sont devenus des avions mythiques de l’armée de l’air américaine (USAF) depuis la fin de la guerre froide. Le bombardier B-2 Spirit a ouvert sa verrière au producteur et journaliste de Defense News Jeff Bolton qui a pu être le co-passager d'un pilote de l'armée. Des vidéos particulièrement rares ont été tournées au sein de l’avion en vol.

L'autonomie du B-2 Spirit est d’environ 9 600 kilomètres. Le bombardier est capable de livrer des munitions conventionnelles et nucléaires. Dans la vidéo, le pilote a la mission délicate de réaliser un ravitaillement en plein vol. L’opération est menée sans mode automatique afin de se coupler avec le Boeing KC-135 Stratotanker.