Astronomy picture of the day - Half Sun with Prominence

 2020 November 2

Half Sun with Prominence
Image Credit & Copyright: Rainee Colacurcio

Explanation: What's happening to the Sun? Clearly, the Sun's lower half is hidden behind a thick cloud. Averaging over the entire Earth, clouds block the Sun about 2/3rds of the time, although much less over many land locations. On the Sun's upper right is a prominence of magnetically levitating hot gas. The prominence might seem small but it could easily envelop our Earth and persist for over a month. The featured image is a combination of two exposures, one optimizing the cloud and prominence, and the other optimizing the Sun's texture. Both were taken about an hour apart with the same camera and from the same location in Lynnwood, Washington, USA. The shaggy texture derives from the Sun's chromosphere, an atmospheric layer that stands out in the specifically exposed color. The uniformity of the texture shows the surface to be relatively calm, indicative of a Sun just past the solar minimum in its 11-year cycle. In the years ahead, the Sun will progress toward a more active epoch where sunspots, prominences, and ultimately auroras on Earth will be more common: solar maximum.

Astronomy picture of the day - In the Center of the Trifid Nebula

 2020 November 1

In the Center of the Trifid Nebula
Image Credit: Subaru Telescope (NAOJ), Hubble Space Telescope, Martin Pugh; Processing: Robert Gendler

Explanation: What's happening at the center of the Trifid Nebula? Three prominent dust lanes that give the Trifid its name all come together. Mountains of opaque dust appear near the bottom, while other dark filaments of dust are visible threaded throughout the nebula. A single massive star visible near the center causes much of the Trifid's glow. The Trifid, cataloged as M20, is only about 300,000 years old, making it among the youngest emission nebulas known. The star forming nebula lies about 9,000 light years away toward the constellation of the Archer (Sagittarius). The region pictured here spans about 10 light years. The featured image is a composite with luminance taken from an image by the 8.2-m ground-based Subaru Telescope, detail provided by the 2.4-m orbiting Hubble Space Telescope, color data provided by Martin Pugh and image assembly and processing provided by Robert Gendler.

Belezas de Braga - Jardim de Santa Bárbara

 

Envolvendo a fonte com a estátua da santa que dá nome ao lugar, o Jardim de Santa Bárbara é situado no centro histórico de Braga e abriga variedades de flores e vegetação bem cuidadas.

O ambiente, assim, é agradável, um dos melhores lugares turísticos de Braga para tomar sol e tirar fotos.

Junto aos muros da ala medieval do Paço Episcopal Bracarense, o jardim ganha vida até de noite, com iluminação que deixa o cenário de flores e muralha medieval ainda mais bonito.

Un avion promet de réduire la pollution des voyages d'affaires

 

La forme ovoïde du Celera 500L permet de diviser la consommation de carburant par 8 et les émissions carbone de 80% par rapport à un avion similaire. Il devrait rentrer en service en 2025.

L'un des problèmes des avions est leur consommation de carburant. Afin de la réduire, la société américaine Otto Aviation a misé sur l'aérodynamisme. La forme ovoïde de son avion d'affaire Celera 500L permet de diviser cette consommation par huit et ses émissions en carbone de 80% par rapport à un avion similaire !

Science & Vie

Astronomy picture of the day - A Galaxy of Horrors

 2020 October 31

A Galaxy of Horrors
Poster Illustration Credit: NASA, JPL-Caltech, The Galaxy of Horrors

Explanation: Explore extreme and terrifying realms of the Universe tonight. If you dare to look, mysterious dark matter, a graveyard galaxy, zombie worlds, and gamma-ray bursts of doom are not all that awaits. Just follow the link and remember, it's all based on real science, even the scary parts. Have a safe and happy halloween!

Astronomy picture of the day - The Ghoul of IC 2118

 2020 October 29

The Ghoul of IC 2118
Image Credit & Copyright: Casey Good/Steve Timmons

Explanation: Inspired by the halloween season, this telescopic portrait captures a cosmic cloud with a scary visage. The interstellar scene lies within the dusty expanse of reflection nebula IC 2118 in the constellation Orion. IC 2118 is about 800 light-years from your neighborhood, close to bright bluish star Rigel at the foot of Orion. Often identified as the Witch Head nebula for its appearance in a wider field of view it now rises before the witching hour though. With spiky stars for eyes, the ghoulish apparition identified here seems to extend an arm toward Orion's hot supergiant star. The source of illumination for IC 2118, Rigel is just beyond this frame at the upper left.

Covid : en ville ou à la campagne, évaluez le risque de croiser une personne infectée

Difficile de ne pas se poser la question en entrant dans un restaurant, dans un magasin ou dans un bureau : combien de personnes sont potentiellement contaminées autour de soi ? Chacun peut désormais estimer ce risque en fonction du lieu où il se trouve et du nombre de personnes qui l'entourent. Le site CovidTracker, créé et animé par un jeune ingénieur en informatique, vient en effet de mettre en ligne un outil aussi simple que pertinent pour prendre la mesure de la circulation du virus autour de soi. Cette simulation, mise au point avec Élias Orphelin, peut s'avérer utile alors que le nombre de nouveaux cas bat des records, avec plus de 52 000 contaminations en 24 heures annoncées dimanche 25 octobre.

Par un simple calcul de probabilité, ce simulateur permet de faire le lien entre un taux d'incidence (soit le nombre de personnes infectées pour 100 000 habitants) et un nombre de personnes croisées à un instant T. « Prenons un exemple théorique, propose le jeune fondateur du site, Guillaume Rozier, dans un mariage de 200 personnes qui aurait lieu à Saint-Étienne, où le taux d'incidence est actuellement de 1 020, le risque de croiser une personne positive parmi les convives serait de 87 %. Si vous êtes invité à une soirée étudiante à Paris, on peut également utiliser des taux d'incidence disponibles par tranche d'âge. Ainsi, dans ce dernier exemple, dans une soirée privée qui rassemblerait 30 étudiants de la capitale, il y aurait une chance sur cinq de tomber sur un invité Covid+. » Avec cet outil, on comprend bien pourquoi les rassemblements sont limités et pourquoi, à certains endroits, mieux vaut les éviter au maximum.

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Le Point - France

Astronomy picture of the day - NGC 6357: The Lobster Nebula

 2020 October 28

NGC 6357: The Lobster Nebula
Image Credit & Copyright: Steven Mohr

Explanation: Why is the Lobster Nebula forming some of the most massive stars known? No one is yet sure. Cataloged as NGC 6357, the Lobster Nebula houses the open star cluster Pismis 24 near its center -- a home to unusually bright and massive stars. The overall blue glow near the inner star forming region results from the emission of ionized hydrogen gas. The surrounding nebula, featured here, holds a complex tapestry of gas, dark dust, stars still forming, and newly born stars. The intricate patterns are caused by complex interactions between interstellar winds, radiation pressures, magnetic fields, and gravity. NGC 6357 spans about 400 light years and lies about 8,000 light years away toward the constellation of the Scorpion.

Astronomy picture of the day : Reflections of the Ghost Nebula

2020 October 26

Reflections of the Ghost Nebula
Image Credit & Copyright: Bogdan Jarzyna

Explanation: Do any shapes seem to jump out at you from this interstellar field of stars and dust? The jeweled expanse, filled with faint, starlight-reflecting clouds, drifts through the night in the royal constellation of Cepheus. Far from your own neighborhood on planet Earth, these ghostly apparitions lurk along the plane of the Milky Way at the edge of the Cepheus Flare molecular cloud complex some 1,200 light-years away. Over two light-years across and brighter than the other spooky chimeras, VdB 141 or Sh2-136 is also known as the Ghost Nebula, seen at toward the bottom of the featured image. Within the reflection nebula are the telltale signs of dense cores collapsing in the early stages of star formation. 

Astronomy picture of the day : Dark Matter in a Simulated Universe

 2020 October 25

Dark Matter in a Simulated Universe
Illustration Credit & Copyright: Tom Abel & Ralf Kaehler (KIPAC, SLAC), AMNH

Explanation: Is our universe haunted? It might look that way on this dark matter map. The gravity of unseen dark matter is the leading explanation for why galaxies rotate so fast, why galaxies orbit clusters so fast, why gravitational lenses so strongly deflect light, and why visible matter is distributed as it is both in the local universe and on the cosmic microwave background. The featured image from the American Museum of Natural History's Hayden Planetarium previous Space Show Dark Universe highlights one example of how pervasive dark matter might haunt our universe. In this frame from a detailed computer simulation, complex filaments of dark matter, shown in black, are strewn about the universe like spider webs, while the relatively rare clumps of familiar baryonic matter are colored orange. These simulations are good statistical matches to astronomical observations. In what is perhaps a scarier turn of events, dark matter -- although quite strange and in an unknown form -- is no longer thought to be the strangest source of gravity in the universe. That honor now falls to dark energy, a more uniform source of repulsive gravity that seems to now dominate the expansion of the entire universe.