Astgronomy picture of the day - 2019 January 6 - A Laser Strike at the Galactic Center

A Laser Strike at the Galactic Center 
Image Credit: Yuri Beletsky (Carnegie Las Campanas Observatory, TWAN), ESO

Explanation: Why are these people shooting a powerful laser into the center of our Galaxy? Fortunately, this is not meant to be the first step in a Galactic war. Rather, astronomers at the Very Large Telescope (VLT) site in Chile are trying to measure the distortions of Earth's ever changing atmosphere. Constant imaging of high-altitude atoms excited by the laser -- which appear like an artificial star -- allow astronomers to instantly measure atmospheric blurring. This information is fed back to a VLT telescope mirror which is then slightly deformed to minimize this blurring. In this case, a VLT was observing our Galaxy's center, and so Earth's atmospheric blurring in that direction was needed. As for inter-galaxy warfare, when viewed from our Galaxy's center, no casualties are expected. In fact, the light from this powerful laser would combine with light from our Sun to together appear only as bright as a faint and distant star.

Astronomy picture of the day - 2019 January 5 - Yutu 2 on the Farside

Yutu 2 on the Farside 
Image Credit: Chinese National Space Administration

Explanation: On January 3, the Chinese Chang'e-4 spacecraft made the first successful landing on the Moon's farside. Taken by a camera on board the lander, this image is from the landing site inside Von Karman crater. It shows the desk-sized, six-wheeled Yutu 2 (Jade Rabbit 2) rover as it rolled down lander ramps and across the surface near local sunrise and the start of the two week long lunar day. Ripe for exploration, Von Karman crater itself is 186 kilometers in diameter. It lies within the Moon's old and deep South Pole-Aitken impact basin with some of the most ancient and least understood lunar terrains. To bridge communications from the normally hidden hemisphere of the Moon, China launched a relay satellite, Queqiao, in May of 2018 in to an orbit beyond the lunar farside.

Reportage video - La Chine réussit le premier alunissage sur la face cachée de la Lune

La fusée transportant le module d’exploration Chang’e-4
décolle du centre de lancement de Xichang (Chine),
le 8 décembre 2018. STR / AFP

Enfin ! Après trois semaines d’attente, la Chine peut célébrer l’alunissage réussi de la mission Chang’e 4. Jeudi 3 janvier à 10 h 26 heure de Pékin (3 h 26 à Paris), l’atterrisseur, qui avait quitté la Terre le 8 décembre, a touché le sol lunaire avec à son bord un engin d’exploration lunaire, au terme d’un voyage de vingt-et-un jours dans l’espace. Il a pris une première photo de la surface peu connue de la Lune, transmise par le satellite Queqiao envoyé dans l’orbite lunaire en mai 2018.

Le Monde

Les meilleurs logiciels 2019 gratuits pour PC - GIMP (Retouche photo)

GIMP est un logiciel très abouti, gratuit et open source de traitement et de retouche photo.

Il est destiné à la fois aux débutants qui peuvent y trouver tous les outils d’édition classiques (découpage, remplissage de zone, texte, brosse, etc.) et une gestion des calques poussée et intuitive. Il convient aussi aux designers graphiques, illustrateurs et photographes grâce à sa multitude d’effets visuels avancés (notamment, flou et distorsion) et à la possibilité d’utiliser, de configurer du matériel dédié comme une tablette graphique avec stylet ou un contrôleur MIDI.

Par ailleurs, les utilisateurs experts ont l'opportunité de rajouter des plug-ins attrayants comme DarkTable pour retoucher vos photos RAW, G’MIC pour ajouter plus de 500 filtres et effets supplémentaires ou l’indispensable Resynthesizer pour enlever avec facilité les objets non désirés d’une photo.

Futura Sciences

Astronomy picture of the day - 2019 January 3 - Ultima and Thule

Ultima and Thule  Image Credit: NASA, Johns Hopkins University APL, Southwest Research Institute

Explanation: On January 1 New Horizons encountered the Kuiper Belt object nicknamed Ultima Thule. Some 6.5 billion kilometers from the Sun, Ultima Thule is the most distant world ever explored by a spacecraft from Earth. This historic image, the highest resolution image released so far, was made at a range of about 28,000 kilometers only 30 minutes before the New Horizons closest approach. Likely the result of a gentle collision shortly after the birth of the Solar System, Ultima Thule is revealed to be a contact binary, two connected sphere-like shapes held in contact by mutual gravity. Dubbed separately by the science team Ultima and Thule, the larger lobe Ultima is about 19 kilometers in diameter. Smaller Thule is 14 kilometers across.

Astronomy picture of the day - 2019 January 2 - The Orion Nebula in Infrared from WISE

The Orion Nebula in Infrared from WISE   Image Credit: WISE, IRSA, NASA; Processing & Copyright : Francesco Antonucci

Explanation: The Great Nebula in Orion is an intriguing place. Visible to the unaided eye, it appears as a small fuzzy patch in the constellation of Orion. But this image, an illusory-color four-panel mosaic taken in different bands ofinfrared light with the Earth orbiting WISE observatory, shows the Orion Nebula to be a bustling neighborhood of recently formed stars, hot gas, and dark dust. The power behind much of the Orion Nebula (M42) is the stars of theTrapezium star cluster, seen near the center of the featured image. The orange glow surrounding the bright stars pictured here is their own starlight reflected by intricate dust filaments that cover much of the region. The current Orion Nebula cloud complex, which includes the Horsehead Nebula, will slowly disperse over the next 100,000 years.

Découvertes médicales récentes : Vaccin contre le cancer

L'Université de Stanford a annoncé le début d'une phase d'expérimentation d'un nouveau traitement contre le cancer. La référence au vaccin ne concerne que le mode d'administration, c'est-à-dire par injection : la substance est cependant composée de deux agents stimulants du système immunitaire capables d'éliminer les cellules cancéreuses.

Curioctopus

Astronomy picture of the day - 2019 January 1 - The Sombrero Galaxy in Infrared

The Sombrero Galaxy in Infrared 
Image Credit: R. Kennicutt (Steward Obs.) et al., SSC, JPL, Caltech, NASA

Explanation: This floating ring is the size of a galaxy. In fact, it is a galaxy -- or at least part of one: the photogenic Sombrero Galaxy, one of the largest galaxies in the nearby Virgo Cluster of Galaxies. The dark band of dust that obscures the mid-section of the Sombrero Galaxy in optical light actually glows brightly in infrared light. The featured image, digitally sharpened, shows the infrared glow, recently recorded by the orbiting Spitzer Space Telescope, superposed in false-color on an existing image taken by NASA's Hubble Space Telescope in optical light. The Sombrero Galaxy, also known as M104, spans about 50,000 light years across and lies 28 million light years away. M104can be seen with a small telescope in the direction of the constellation Virgo.

Astronomy picture of the day - 2018 December 31 - The Witch Head Nebula

The Witch Head Nebula  
Image Credit & Copyright: Digitized Sky Survey (POSS II); Processing: Utkarsh Mishra

Explanation: Double, double toil and trouble; Fire burn, and cauldron bubble .... maybe Macbeth should have consulted the Witch Head Nebula. A frighteningly shaped reflection nebula, this cosmic crone is about 800 light-years away though. Its malevolent visage seems to glare toward nearby bright star Rigel in Orion, just off the right edge of this frame. More formally known as IC 2118, the interstellar cloud of dust and gas is nearly 70 light-years across, its dust grains reflecting Rigel's starlight. In this composite portrait, the nebula's color is caused not only by the star's intense bluish light but because the dust grains scatter blue light more efficiently than red. The same physical process causes Earth's daytime sky to appear blue, although the scatterers in planet Earth's atmosphere are molecules of nitrogen and oxygen.

Astronomy picture of the day - 2018 December 30 - The Galaxy Tree

The Galaxy Tree  
Image Credit & Copyright: César Vega Toledano ; Rollover Annotation: Judy Schmidt

Explanation: First came the trees. In the town of Salamanca, Spain, the photographer noticed how distinctive a grove of oak trees looked after being pruned. Next came the galaxy. The photographer stayed up until 2 am, waiting until the Milky Way Galaxy rose above the level of a majestic looking oak. From this carefully chosen perspective, dust lanes in the galaxy appear to be natural continuations to branches of the tree. Last came the light. A flashlight was used on the far side of the tree to project a silhouette. By coincidence, other trees also appeared as similar silhouettes across the relatively bright horizon. The featured image was captured as a single 30-second frame in 2015 and processed to digitally enhance the Milky Way.