ASTRONOMY - Trail of the Returner

 2020 December 31

Trail of the Returner
Image Credit & Copyright: Zhuoxiao Wang

Explanation: Familiar stars of a northern winter's night shine in this night skyview, taken near Zhangye, Gansu, China and the border with Inner Mongolia. During the early hours of December 17 Orion is near center in the single exposure that captures a fireball streaking across the sky, almost as bright as yellowish Mars shining on the right. Splitting Gemini's twin bright stars Castor and Pollux near the top of the frame, the fireball's trail and timing are consistent with the second skipping atmospheric entry of the Chang'e 5 mission's returner capsule. The returner capsule was successfully recovered after landing in Inner Mongolia, planet Earth with about 2 kilograms of lunar material on board. The lunar sample is thought to contain relatively young material collected near the Mons Rumker region of the Moon's Oceanus Procellarum. Launched on November 23 UT, China's Chang'e 5 mission is the first lunar sample return mission since the Soviet Union’s Luna 24 mission in 1976.

PRATIQUE - Comment faire des symboles sur un clavier

 

METAPHYSIQUE - Sommes-nous tout seuls dans l'Univers ?

 

ASTRONOMY - Earth During a Total Solar Eclipse

 2020 December 29

Earth During a Total Solar Eclipse
Video Credit: GOES-16, ABI, NOAA, NASA

Explanation: What does the Earth look like during a total solar eclipse? It appears dark in the region where people see the eclipse, because that's where the shadow of the Moon falls. The shadow spot rapidly shoots across the Earth at nearly 2,000 kilometers per hour, darkening locations in its path -- typically for only a few minutes -- before moving on. The featured video shows the Earth during the total solar eclipse earlier this month. The time-lapse sequence, taken from a geostationary satellite, starts with the Earth below showing night but the sun soon rises at the lower right. Clouds shift as day breaks over the blue planet. Suddenly the circular shadow of the Moon appears on the left and moves rapidly across South America, disappearing on the lower right. The video ends as nightfall begins again. The next total solar eclipse will occur next December -- but be visible only from parts of Antarctica.

Coronavirus : oui, on peut laver son masque jetable

Un masque jetable doit être jeté au bout de quatre heures d'utilisation : c'est ce que vous avez entendu partout. Les masques chirurgicaux sont pourtant parfaitement lavables et réutilisables, atteste sur France Bleu Philippe Vroman, enseignant-chercheur au laboratoire Gemtex de l'Ensait à Roubaix. Il faut savoir que le masque chirurgical tire son efficacité de deux points. Premièrement, sa matière, constituée de trois épaisseurs : une couche de meltblown, un textile non tissé très filtrant dérivé du polypropylène, pris en sandwich entre deux couches de spunbond, aux fibres beaucoup plus grosses et servant de matériau support. Deuxièmement, on ajoute sur ce masque une charge électrostatique qui « retient » les particules virales.

Quand on mouille le masque, ce dernier perd sa charge électrostatique : c'est pour cela qu'on conseille de le changer lorsqu'il est humide. « Mais comme ce masque a une efficacité globalement supérieure aux autres masques, même après avoir été lavé et donc perdu sa charge électrostatique, il reste globalement plus efficace que les autres », assure Philippe Vroman. Une fois lavé, le meltblown filtre encore 95 % des particules de moins de trois microns, contre 90 % pour les masques en tissu grand public, explique le spécialiste.

Mais combien de fois est-il réutilisable ? « C'est une bonne question ! Aujourd'hui, on fait des études pour vérifier la capacité de ce masque à être réutilisable. La piste n'avait pas été explorée jusqu'à présent puisque ça n'était pas l'usage du masque chirurgical. Mais comme on a des résultats intéressants jusqu'à cinq lavages, nous allons étudier sa tenue », indique Philippe Vroman. Même en prenant une base de cinq lavages, cela permet de beaucoup réduire le gaspillage, la pollution... et le coût.

Futura Sciences

MUSICA - Verdi - Va piensero

"Va piensero"

 

MUSICA - Feliz Navidad

"FELIZ NAVIDAD"

 

VOLCANOLOGY - A Volcanic Great Conjunction

 2020 December 20

A Volcanic Great Conjunction
Image Credit & Copyright: Francisco Sojuel

Explanation: Where can I see the Great Conjunction? Near where the Sun just set. Directionally, this close passing of Jupiter and Saturn will be toward the southwest. Since the planetary pair, the Sun, and the Earth are nearly in a geometric straight line, the planets will be seen to set just where the Sun had set -- from every location on Earth. When can I see the Great Conjunction? Just after sunset. Since the two planets are so near the Sun directionally, they always appear in the sky near the Sun, but can best be seen when the Earth blocks the Sun but not the planets: sunset. Soon thereafter, Jupiter and Saturn will also set, so don't be late! Is tomorrow night the only night that I can see the Great Conjunction? Tomorrow night the jovian giants will appear the closest, but on any night over the next few days they will appear unusually close. Technically, the closest pass happens on 21 December at 18:20 UTC. Will there be an erupting volcano on the horizon near the Great Conjunction? Yes, for example if you live in Guatemala where the featured image was taken. Otherwise, generally, no. In the featured image captured last week, Jupiter and Saturn are visible toward the right, just above a tree, and bathed in the diffuse glow of zodiacal light.

PRATIQUE - Comment faire fuir les mouches

 

PRATIQUE - Nettoyer facilement clavier PC

 

ASTRONOMY - Conjunction after Sunset

 2020 December 19

Conjunction after Sunset
Image Credit & Copyright: Alireza Vafa

Explanation: How close will Jupiter and Saturn be at their Great Conjunction? Consider this beautiful triple conjunction of Moon, Jupiter and Saturn captured through clouds in the wintry twilight. The telephoto view looks toward the western horizon and the Alborz Mountains in Iran after sunset on December 17. The celestial gathering makes it easy to see Jupiter and fainter Saturn are separated on that date by roughly the diameter of the waxing crescent Moon. On the day of their Great Conjunction, solstice day December 21, Jupiter and Saturn may seem to nearly merge though. In their closest conjunction in 400 years they will be separated on the sky by only about 1/5 the apparent diameter of the Moon. By then the two largest worlds in the Solar System and their moons will be sharing the same field of view in telescopes around planet Earth.

ASTRONOMY - Diamond in the sky

 2020 December 18

Diamond in the Sky
Image Credit & Copyright: Mariano Ribas (Planetario de la Ciudad de Buenos Aires)

Explanation: When the shadow of the Moon raced across planet Earth's southern hemisphere on December 14, sky watchers along the shadow's dark central path were treated to the only total solar eclipse of 2020. During the New Moon's shadow play this glistening diamond ring was seen for a moment, even in cloudy skies. Known as the diamond ring effect, the transient spectacle actually happens twice. Just before and immediately after totality, a thin sliver of solar disk visible behind the Moon's edge creates the appearance of a shiny jewel set in a dark ring. This dramatic snapshot from the path of totality in northern Patagonia, Argentina captures this eclipse's second diamond ring, along with striking solar prominences lofted beyond the edge of the Moon's silhoutte.

ASTRONOMY - Gemini's Meteors

 2020 December 17

Gemini's Meteors
Image Credit & Copyright: Stefano Pellegrini

Explanation: Taken over the course of an hour shortly after local midnight on December 13, 35 exposures were used to create this postcard from Earth. The composited night scene spans dark skies above the snowy Italian Dolomites during our fair planet's annual Geminid meteor shower. Sirius, alpha star of Canis Major and the brightest star in the night, is grazed by a meteor streak on the right. The Praesepe star cluster, also known as M44 or the Beehive cluster, itself contains about a thousand stars but appears as a smudge of light far above the southern alpine peaks near the top. The shower's radiant is off the top of the frame though, near Castor and Pollux the twin stars of Gemini. The radiant effect is due to perspective as the parallel meteor tracks appear to converge in the distance. As Earth sweeps through the dust trail of asteroid 3200 Phaethon, the dust that creates Gemini's meteors enters Earth's atmosphere traveling at about 22 kilometers per second.

PRATIQUE - Comment retrouver des petits objets

 

AERONAUTIQUE - La voiture volante

 

Hildebrands, une célèbre marque de chocolat allemand dans les années 1900, nous imaginait chacun en possession d'une voiture volante. Ces dessins suggèrent différents types d'appareils, allant des ailes de chauve-souris à la baignoire surmontant quatre ailes improbables. Ils nous font aujourd'hui sourire par leur optimisme mais sont surtout révélateurs de l'époque des pionniers de l'aviation qui laissait présager un futur aérien...

© Hildebrands

ASTRONOMY - Sonified: The Matter of the Bullet Cluster

 2020 December 16

Sonified: The Matter of the Bullet Cluster
Image Credit: X-ray: NASA/CXC/SAO; Optical: NASA/STScI, Magellan/U.Arizona; Lensing Map: NASA/STScI, ESO WFI, Magellan/U.Arizona; Sonification: NASA/CXC/SAO/K.Arcand, SYSTEM Sounds (M. Russo, A. Santaguida)

Explanation: What's the matter with the Bullet Cluster? This massive cluster of galaxies (1E 0657-558) creates gravitational lens distortions of background galaxies in a way that has been interpreted as strong evidence for the leading theory: that dark matter exists within. Different analyses, though, indicate that a less popular alternative -- modifying gravity-- could explain cluster dynamics without dark matter, and provide a more likely progenitor scenario as well. Currently, the two scientific hypotheses are competing to explain the observations: it's invisible matter versus amended gravity. The duel is dramatic as a clear Bullet-proof example of dark matter would shatter the simplicity of modified gravity theories. The featured sonified image is a Hubble/Chandra/Magellan composite with red depicting the X-rays emitted by hot gas, and blue depicting the suggested separated dark matter distribution. The sonification assigns low tones to dark matter, mid-range frequencies to visible light, and high tones to X-rays. The battle over the matter in the Bullet cluster is likely to continue as more observations, computer simulations, and analyses are completed.

SPACE ART - David Hardy

 

Autoportrait de l’artiste David Hardy peignant sur Io, lune de Jupiter. Crédit : David Hardy

PRATIQUE - La cuillère en bois magique !

 

ASTRONOMY - Geminid Meteors over Xinglong Observatory

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ASTRONOMY - Messier Craters in Stereo

 2020 December 11

Messier Craters in Stereo
Image Credit: Apollo 11, NASA; Stereo Image Copyright Patrick Vantuyne

Explanation: Many bright nebulae and star clusters in planet Earth's sky are associated with the name of astronomer Charles Messier from his famous 18th century catalog. His name is also given to these two large and remarkable craters on the Moon. Standouts in the dark, smooth lunar Sea of Fertility or Mare Fecunditatis, Messier (left) and Messier A have dimensions of 15 by 8 and 16 by 11 kilometers respectively. Their elongated shapes are explained by the extremely shallow-angle trajectory followed by an impactor, moving left to right, that gouged out the craters. The shallow impact also resulted in two bright rays of material extending along the surface to the right, beyond the picture. Intended to be viewed with red/blue glasses (red for the left eye), this striking stereo picture of the crater pair was recently created from high resolution scans of two images (AS11-42-6304, AS11-42-6305) taken during the Apollo 11 mission to the Moon.

PRATIQUE - La pelle remplit le seau

 

ASTRONOMY - Arecibo Telescope Collapse

 2020 December 9

Arecibo Telescope Collapse
Video Credit: Arecibo Observatory, NSF

Explanation: This was one great scientific instrument. Starting in 1963, the 305-meters across Arecibo Telescope in Puerto Rico USA reigned as the largest single-dish radio telescope in the world for over 50 years. Among numerous firsts and milestones, data from Arecibo has been used to measure the spin of Mercury, map the surface of Venus, discover the first planets outside of our Solar System, verify the existence of gravitational radiation, search for extraterrestrial intelligence, and, reportedly, locate hidden military radar by tracking their reflections from the Moon. Past its prime and in the process of being decommissioned, the Arecibo Telescope suffered a catastrophic structural collapse early this month, as seen in the featured composite video.

ASTRONOMY - Great Conjunction over Sicilian Lighthouse

 2020 December 8

Great Conjunction over Sicilian Lighthouse
Image Credit & Copyright: Kevin Saragozza

Explanation: Don’t miss the coming great conjunction. In just under two weeks, the two largest planets in our Solar System will angularly pass so close together in Earth's sky that the Moon would easily be able to cover them both simultaneously. This pending planetary passage -- on December 21 -- will be the closest since 1623. Jupiter and Saturn will remain noticeably bright and can already be seen together toward the southwest just after sunset. Soon after dusk is the best time to see them -- because they set below the horizon soon after. In mid-November, the Jovian giants were imaged together here about three degrees apart -- and slowly closing. The featured image, including a crescent moon, captured the dynamic duo beyond the Cape Murro di Porco Lighthouse in Syracuse, Sicily, Italy.

PRATIQUE - Enceinte puissante

 

METEOROLOGY - Mammatus Clouds over Mount Rushmore

 2020 December 7

Mammatus Clouds over Mount Rushmore
Image Credit & Copyright: Laure Mattuzzi

Explanation: What's that below those strange clouds? Presidents. If you look closely, you may recognize the heads of four former US Presidents carved into famous Mount Rushmore in South Dakota, USA. More obvious in the featured image are the unusual mammatus clouds that passed briefly overhead. Both were captured together by a surprised tourist with a quick camera in early September. Unlike normal flat-bottomed clouds which form when moist and calm air plateaus rise and cool, bumpy mammatus clouds form as icy and turbulent air pockets sink and heat up. Such turbulent air is frequently accompanied by a thunderstorm. Each mammatus lobe spans about one kilometer. The greater mountain is known to native Lakota Sioux as Six Grandfathers, deities responsible for the directions north, south, east, west, up, and down.

AERONAUTIQUE - Boeing - projet X48

Douglas dans les années 1990. Le projet s'est poursuivi sous la forme d'une collaboration avec la Nasa et l'université britannique de Cranfield pour un appareil à fuselage porteur. Après le X48A, resté dans les cartons, deux modèles réduits baptisés X48B ont été construits et testés en vol. Une autre version, le X48C, a été testé en vol également entre 2012 et 2013.

En 2011, Boeing a présenté ce projet à la Nasa dans le cadre de son étude sur les avions de 2025. On voit ici une image d'artiste avec deux types de motorisation. Les moteurs sont installés sur la partie supérieure, ce qui réduit le bruit perçu au sol. 

© Nasa, The Boeing Company

PRATIQUE - Vêtements parfumés

 

ASTRONOMY - M16: Pillars of Star Creation

 2020 December 6

M16: Pillars of Star Creation
Image Credit: NASA, ESA, Hubble Space Telescope, J. Hester, P. Scowen (ASU)

Explanation: These dark pillars may look destructive, but they are creating stars. This pillar-capturing image of the inside of the Eagle Nebula, taken with the Hubble Space Telescope in 1995, shows evaporating gaseous globules (EGGs) emerging from pillars of molecular hydrogen gas and dust. The giant pillars are light years in length and are so dense that interior gas contracts gravitationally to form stars. At each pillars' end, the intense radiation of bright young stars causes low density material to boil away, leaving stellar nurseries of dense EGGs exposed. The Eagle Nebula, associated with the open star cluster M16, lies about 7000 light years away. The pillars of creation have been imaged more recently in infrared light by Hubble, NASA's Spitzer Space Telescope, and ESA's Herschel Space Observatory -- showing new detail.

AERONAUTIQUE - Marcher sur l'eau

Dans les années 1900, une célèbre marque de chocolat leader sur son marché, Hildebrands, agrémentait ses tablettes de cartes postales imaginant l'an 2000. Celle-ci illustre la croyance selon laquelle, à l'aide de ballons gonflables, nous pourrions nous balader en marchant sur l'eau. Vous remarquerez les très pratiques petites chaussures-péniches en bois pour éviter de mouiller ses souliers.

© Hildebrands

ASTRONOMY - Mons Rumker in the Ocean of Storms

 2020 December 5

Mons Rumker in the Ocean of Storms
Image Credit & Copyright: Jean-Yves Letellier

Explanation: Mons Rumker, a 70 kilometer wide complex of volcanic domes, rises some 1100 meters above the vast, smooth lunar mare known as Oceanus Procellarum, the Ocean of Storms. Daylight came to the area late last month. The lunar terminator, the shadow line between night and day, runs diagonally across the left side in this telescopic close-up of a waxing gibbous Moon from November 27. China's Chang'e-5 mission landing site is also in the frame. The probe's lander-ascender combination touch down on the lunar surface within a region right of center and north of Mons Rumker's domes on December 1. On December 3 the ascender left the Ocean of Storms carrying 2 kilograms of lunar material for return to planet Earth.

ASTRONOMY - Curly Spiral Galaxy M63

 2020 December 4

Curly Spiral Galaxy M63
Image Credit & Copyright: Fabian Neyer, Rainer Spani
Collaboration Credit: I.D. Karachentsev, F. Neyer, R. Spani, T. Zilch

Explanation: A bright spiral galaxy of the northern sky, Messier 63 is nearby, about 30 million light-years distant toward the loyal constellation Canes Venatici. Also cataloged as NGC 5055, the majestic island universe is nearly 100,000 light-years across, about the size of our own Milky Way. Its bright core and majestic spiral arms lend the galaxy its popular name, The Sunflower Galaxy, while this exceptionally deep exposure also follows faint, arcing star streams far into the galaxy's halo. Extending nearly 180,000 light-years from the galactic center the star streams are likely remnants of tidally disrupted satellites of M63. Other satellite galaxies of M63 can be spotted in this remarkable wide-field image, made with a small telescope, including five newly identified faint dwarf galaxies, which could contribute to M63's star streams in the next few billion years.

PRATIQUE - Rangez vos boules !

 

MUSICA - The Three Tenors - "Libiamo ne' lieti calici"

"Libiamo ne' lieti calici"

ASTRONOMY - The Antennae Galaxies in Collision

 2020 December 3

The Antennae Galaxies in Collision
Image Credit: ESA/Hubble NASA

Explanation: Sixty million light-years away toward the southerly constellation Corvus, these two large galaxies are colliding. The cosmic train wreck captured in stunning detail in this Hubble Space Telescope snapshot takes hundreds of millions of years to play out. Cataloged as NGC 4038 and NGC 4039, the galaxies' individual stars don't often collide though. Their large clouds of molecular gas and dust do, triggering furious episodes of star formation near the center of the wreckage. New star clusters and interstellar matter are jumbled and flung far from the scene of the accident by gravitational forces. This Hubble close-up frame is about 50,000 light-years across at the estimated distance of the colliding galaxies. In wider-field views their suggestive visual appearance, with extended structures arcing for hundreds of thousands of light-years, gives the galaxy pair its popular name, The Antennae Galaxies.

PRATIQUE - Le fond du sac poubelle

 

AERONAUTIQUE - La Mongolfière familiale

 

Dans les années 1900, certaines personnes avaient imaginé des engins volants de différentes tailles (un peu comme le principe des voitures berlines familiales d'aujourd'hui) largement calqués sur les montgolfières. En effet, un peu plus d'un siècle plus tôt, les frères Montgolfier (Joseph-Michel et Jacques-Étienne) avaient fait voler le premier ballon gonflé d'air chaud. Dans l'imaginaire populaire, le ballon était donc l'une des seules formes d'objets volants connues.

Futura Sciences

ASTRONOMY - Eye of moon

 2020 December 2

Eye of Moon
Image Credit & Copyright: Zachery Cooley

Explanation: Who's watching who? The featured image of the Moon through a gap in a wall of rock may appear like a giant eye looking back at you. Although, in late October, it took only a single exposure to capture this visual double, it also took a lot of planning. The photographic goal was achieved by precise timing -- needed for a nearly full moon to appear through the eye-shaped arch, by precise locating -- needed for the angular size of the Moon to fit iconically inside the rock arch, and by good luck -- needed for a clear sky and for the entire scheme to work. The seemingly coincidental juxtaposition was actually engineered with the help of three smartphone apps. The pictured sandstone arch, carved by erosion, is millions of years old and just one of thousands of natural rock arches that have been found in Arches National Park near Moab, Utah, US

PRATIQUE - Repasser les chemises

 

PRATIQUE - Valise à l'aéroport

 

ASTRONOMY - NGC 346: Star Forming Cluster in the SMC

 2020 December 1

NGC 346: Star Forming Cluster in the SMC
Image Credit & License: NASA, ESA, Hubble; Processing: Judy Schmidt

Explanation: Are stars still forming in the Milky Way's satellite galaxies? Found among the Small Magellanic Cloud's (SMC's) clusters and nebulas, NGC 346 is a star forming region about 200 light-years across, pictured here in the center of a Hubble Space Telescope image. A satellite galaxy of the Milky Way, the Small Magellanic Cloud (SMC) is a wonder of the southern sky, a mere 210,000 light-years distant in the constellation of the Toucan (Tucana). Exploring NGC 346, astronomers have identified a population of embryonic stars strung along the dark, intersecting dust lanes visible here on the right. Still collapsing within their natal clouds, the stellar infants' light is reddened by the intervening dust. Toward the top of the frame is another star cluster with intrinsically older and redder stars. A small, irregular galaxy, the SMC itself represents a type of galaxy more common in the early Universe. These small galaxies, though, are thought to be building blocks for the larger galaxies present today.