Science et Technologie - Le monde minéral et ses trésors cachés : Calcédoine aux mille couleurs

Calcédoine aux mille couleurs

On qualifie d'agates les calcédoines présentant plusieurs couleurs. Ces colorations peuvent se présenter en zones parallèles, concentriques ou se répartir dans la masse de façon irrégulière. À noter ici la finesse des lignes colorées et les tubes d'échappement de gaz dans cette agate du Brésil.

Bruno Cupillard

Science & Technology - Astronomy picture of the day : Sharpest Ultima Thule

2019 February 28
Sharpest Ultima Thule 
Image Credit: NASA, Johns Hopkins University APL, Southwest Research Institute, National Optical Astronomy Observatory

Explanation: On January 1, New Horizons swooped to within 3,500 kilometers of the Kuiper Belt world known as Ultima Thule. That's about 3 times closer than its July 2015 closest approach to Pluto. The spacecraft's unprecedented feat of navigational precision, supported by data from ground and space-based observing campaigns, was accomplished 6.6 billion kilometers (over 6 light-hours) from planet Earth. Six and a half minutes before closest approach to Ultima Thule it captured the nine frames used in this composite image. The most detailed picture possible of the farthest object ever explored, the image has a resolution of about 33 meters per pixel, revealing intriguing bright surface features and dark shadows near the terminator. A primitive Solar System object, Ultima Thule's two lobes combine to span just 30 kilometers. The larger lobe, referred to as Ultima, is recently understood to be flattenedlike a fluffy pancake, while the smaller, Thule, has a shape that resembles a dented walnut.

Science & Tecnology - Astronomy picture of the day : Magnetic Orion

2019 February 27
Magnetic Orion 
Image Credit & Copyright: NASA, SOFIA, D. Chuss et al. & ESO, M. McCaughrean et al.

Explanation: Can magnetism affect how stars form? Recent analysis of Orion data from the HAWC+ instrument on the airborne SOFIA observatory indicate that, at times, it can. HAWC+ is able to measure the polarization of far-infrared light which can reveal the alignment of dust grains by expansive ambient magnetic fields. In the featured image, these magnetic fields are shown as curvy lines superposed on an infrared image of the Orion Nebula taken by aVery Large Telescope in Chile. Orion's Kleinmann-Low Nebula is visible slightly to the upper right of the image center, while bright stars of the Trapezium cluster are visible just to the lower left of center. The Orion Nebula at about l300 light years distant is the nearest major star formation region to the Sun.

Science et Technologies - Le monde minéral et ses trésors cachés : "Agate de Chine aux formes surréalistes"

"Agate de Chine aux formes surréalistes"

Comme dans la peinture surréaliste de Joan Miró, cette agate de Chine présente une construction de signes et de formes colorées.

 Bruno Cupillard

Science & Technology - Astronomy picture of the day : Simulation TNG50: A Galaxy Cluster Forms

2019 February 26
Simulation TNG50: A Galaxy Cluster Forms Video Credit: IllustrisTNG Project; Visualization: Dylan Nelson (Max Planck Institute for Astrophysics) et al.
Music: Symphony No. 5 (Ludwig van Beethoven), via YouTube Audio Library

Explanation: How do clusters of galaxies form? Since our universe moves too slowly to watch, faster-moving computer simulations are created to help find out. A recent effort is TNG50 from IllustrisTNG, an upgrade of the famous Illustris Simulation. The first part of the featured video tracks cosmic gas (mostly hydrogen) as it evolves into galaxies and galaxy clusters from the early universe to today, with brighter colors marking faster moving gas. As the universe matures, gas falls into gravitational wells, galaxies forms, galaxies spin, galaxies collide and merge, all while black holes form in galaxy centers and expel surrounding gas at high speeds. The second half of the video switches to tracking stars, showing a galaxy cluster coming together complete with tidal tails and stellar streams. The outflow from black holes in TNG50 is surprisingly complex and details are being compared with our real universe. Studying how gas coalesced in the early universe helps humanity better understand how our Earth, Sun, and Solar System originally formed.

Science & Technology - Astronomy picture of the day : Red Sprite Lightning over Kununurra

2019 February 25
Red Sprite Lightning over Kununurra 

Image Credit & Copyright: Ben Broady

Explanation: What are those red filaments in the sky? It is a rarely seen form of lightning confirmed only about 30 years ago: red sprites. Recent research has shown that following a powerful positive cloud-to-ground lightning strike,red sprites may start as 100-meter balls of ionized air that shoot down from about 80-km high at 10 percent the speed of light and are quickly followed by a group of upward streaking ionized balls. The featured image, taken just over a week ago in Kununurra, Western Australia, captured some red sprites while shooting a time-lapse sequence of a distant lightning storm. Pictured, green trees cover the foreground, dark mountains are seen on the horizon, ominousstorm clouds hover over the distant land, while red sprites appear in front of stars far in the distance. Red sprites take only a fraction of a second to occur and are best seen when powerful thunderstorms are visible from the side.

Science et Technologie - Le monde minéral et ses trésors cachés : "Rhodochrosite de Capillitas issue d'une stalactite

"Rhodochrosite de Capillitas issue d'une stalactite"

Cette rhodochrosite provient de la mine de Capillitas, en Argentine. Ce carbonate de manganèsedoit son nom au grec « rhodon » signifiant « rose » et « khrozo », « coloré ». Le site de Capillitas se présente sous la forme de cavités dotées de stalactites impressionnantes dont certaines mesurent plus d'un mètre. Ici la coupe de cette stalagmite alterne des festons rosés, blancs et carmins aux tonalités pâles à soutenues.

Bruno Cupillard

Science & Technologie - Le monde minéral et ses trésors cachés : "Agate aux couleurs flamboyantes"

"Agate aux couleurs flamboyantes"

Bruno Cupillard

Science & Tecnology - Astronomy picture : Doomed Star Eta Carinae

2019 February 20
Doomed Star Eta Carinae  Image Credit: NASA, ESA, Hubble; Processing & License: Judy Schmidt

Explanation: Eta Carinae may be about to explode. But no one knows when - it may be next year, it may be one million years from now. Eta Carinae's mass - about 100 times greater than our Sun - makes it an excellent candidate for a full blown supernova. Historical records do show that about 170 years ago Eta Carinae underwent an unusual outburst that made it one of the brightest stars in the southern sky. Eta Carinae, in the Keyhole Nebula, is the only starcurrently thought to emit natural LASER light. This featured image brings out details in the unusual nebula that surrounds this rogue star. Diffraction spikes, caused by the telescope, are visible as bright multi-colored streaks emanating from Eta Carinae's center. Two distinct lobes of the Homunculus Nebula encompass the hot central region, while some strange radial streaks are visible in red extending toward the image right. The lobes are filled with lanes of gas anddust which absorb the blue and ultraviolet light emitted near the center. The streaks, however, remain unexplained.

Sciences et Technologie - Le monde minéral et ses trésors cachés - "Jaspe orbiculaire aux allures de lagon bleu"

"Jaspe orbiculaire aux allures de lagon bleu"

Le jaspe orbiculaire est une calcédoine (silice) plus ou moins opaque créée suite à l'apport d'argileet de pigments divers. Ici, les vides d'une coulée de rhyolite se sont emplis, accueillant un choix étonnant de couleurs et de formes.

Science & Technology - Astronomy picture - Dragon Aurora over Iceland

Dragon Aurora over Iceland Image Credit & Copyright: Jingyi Zhang & Wang Zheng

Explanation: Have you ever seen a dragon in the sky? Although real flying dragons don't exist, a huge dragon-shaped aurora developed in the sky over Iceland earlier this month. The aurora was caused by a hole in the Sun's coronathat expelled charged particles into a solar wind that followed a changing interplanetary magnetic field to Earth's magnetosphere. As some of those particles then struck Earth's atmosphere, they excited atoms which subsequently emitted light: aurora. This iconic display was so enthralling that the photographer's mother ran out to see it and was captured in the foreground. No sunspots have appeared on the Sun so far in February, making the multiple days of picturesque auroral activity this month somewhat surprising.

Sciences et Technologie - Le monde minéral et ses trésors cachés - "Agate onyx noire à bandes blanches"

"Agate onyx noire à bandes blanches"

Il existe plusieurs types d'agates. L'agate fortifiée présente des dessins angulaires qui évoquent des fortifications. L'agate mousse est translucide. Elle est parcourue d'inclusions à base de chlorite verte. L'agate onyx est noire à bandes blanches, alors que la sardonyx alterne les couches brunes, orangées et blanches.

Bruno Cupillard

Sciences et Technologie - Le monde minéral et ses trésors cachés - "Jaspe orbiculaire de Mahajanga, Madagascar"

"Jaspe orbiculaire de Mahajanga, Madagascar"

Parsemé de cercles concentriques serrés les uns contre les autres, ce jaspe particulièrement esthétique provient de la province de Mahajanga, près de Marovato, au nord-ouest de Madagascar.

Bruno Cupillard

Science & Technology - Shadow of a Martian Robot

Shadow of a Martian Robot  
Image Credit: Mars Exploration Rover Mission, JPL, NASA

Explanation: What if you saw your shadow on Mars and it wasn't human? Then you might be the Opportunity rover currently exploring Mars. Opportunity explored the red planet from 2004 to 2018, finding evidence of ancient water, and sending breathtaking images across the inner Solar System. Pictured here in 2004, Opportunity looks opposite the Sun into Endurance Crater and sees its own shadow. Two wheels are visible on the lower left and right, while the floor and walls of the unusual crater are visible in the background. Caught in a dust storm in 2018, last week NASA stopped try contact Opportunity and declare the ground-breaking mission, originally planned for only 92 days,complete.

Sciences et Technologie - Le monde minéral et ses trésors cachés - "Agate du Brésil"

"Agate du Brésil"

L'agate est une matière composée de silice et colorée par des oxydes. C'est une calcédoine ou quartz polycristallin. En fonction de leur aspect, les agates ont reçu des noms évocateurs : agate mousse, agate rubanée, agate œillée, agate festonnée, agate plume, agate arborisée, agate paysage.

Bruno Cupillard

Science & Tecnology - Astronomy picture of the day : Plane Crossing a Crescent Moon - 2019 February 15

Plane Crossing a Crescent Moon 

Image Credit & Copyright: Olivier Staiger (Binounistan.com)

Explanation: No, this is not a good way to get to the Moon. What is pictured is a chance superposition of an airplane and the Moon. The contrail would normally appear white, but the large volume of air toward the setting Sun preferentially knocks away blue light, giving the reflected trail a bright red hue. Far in the distance, well behind the plane, is a crescent Moon, also slightly reddened. Captured a month ago above Valais, Switzerland, the featured image was taken so soon after sunset that planes in the sky were still in sunlight, as were their contrails. Within minutes, unfortunately, the impromptu sky show ended. The plane crossed the Moon and moved out of sight. The Moon set. The contrail became unilluminated and then dispersed.

Science & Tecnology - Astronomy picture of the day - 2019 February 11 : "New Data: Ultima Thule Surprisingly Flat"

New Data: Ultima Thule Surprisingly Flat  
Illustration Credit: NASA, JHU's APL, SwRI

Explanation: Ultima Thule is not the object humanity thought that it was last month. When the robotic New Horizons spacecraft zoomed past the distant asteroid Ultima Thule (officially 2014 MU69) in early January, early imagesshowed two circular lobes that when most simply extrapolated to 3D were thought to be, roughly, spheres. However, analyses of newly beamed-back images -- including many taken soon after closest approach -- shows eclipsed stars re-appearing sooner than expected. The only explanation possible is that this 30-km long Kuiper belt object has a different 3D shape than believed only a few weeks ago. Specifically, as shown in the featured illustration, it now appears that the larger lobe -- Ultima -- is more similar to a fluffy pancake than a sphere, while the smaller lobe -- Thule -- resembles a dented walnut. The remaining uncertainty in the outlines are shown by the dashed blue lines. The new shape information indicates that gravity -- which contracts more massive bodies into spheres -- played perhaps less of a role in contouring the lobes of Ultima Thule than previously thought. The New Horizons spacecraft continued on to Ultima Thule after passing Pluto in mid-2015. New data and images are still being received.

Moon and Venus Appulse over a Tree - Astronomy picture of the day - 2019 February 9

Moon and Venus Appulse over a Tree 

Image Credit & Copyright: Alex Dzierba

Explanation: What's that bright spot near the Moon? Venus. About a week ago, Earth's Moon appeared unusually close to the distant planet Venus, an angular coincidence known as an appulse. Similar to a conjunction, which is acoordinate term, an appulse refers more generally to when two celestial objects appear close together. This Moon and Venus appulse -- once as close as 0.05 degrees -- was captured rising during the early morning behind Kokocrater on the island of O'ahu in Hawaii, USA. The Moon was in a crescent phase with its lower left reflecting direct sunlight, while the rest of the Moon is seen because of Earthshine, sunlight first reflected from the Earth. Some leaves and branches of a foreground kiawe tree are seen in silhouette in front of the bright crescent, while others, in front of a darker background, appear white because of forward scattering. Appulses involving the Moon typically occurseveral times a year: for example the Moon is expected to pass within 0.20 degrees of distant Saturn on March 1.

Science & Technologie - Video - "On a vu la mort"

Dans les organes, dans le cerveau, dans les cellules... la science a découvert ce qui se passe dans le corps quand on meurt. Une chronique de Thomas Cavaillé-Fol sur Science & Vie TV.

En 2018, trois expériences différentes ont permis de voir la mort... et même de la filmer ! Surprise : mourir, ce n'est pas s'éteindre d'un coup. Au contraire, c'est un processus auquel prennent part tous nos organes et cellules, par l'activation de certains gènes. Tout commence dans le cerveau, où la faucheuse frappe en premier. Récit de comment la vie quitte le corps par Thomas Cavaillé-Fol, journaliste au magazine Science & Vie.

Science & Vie

Science & Technology - Astronomy picture of the day - 2019 February 5 : Perijove 16: Passing Jupiter

Perijove 16: Passing Jupiter 
Video Credit & License: NASA, Juno, SwRI, MSSS, Gerald Eichstadt;  Music: The Planets, IV. Jupiter (Gustav Holst); USAF Heritage of America Band (via Wikipedia)

Explanation: Watch Juno zoom past Jupiter again. NASA's robotic spacecraft Juno is continuing on its 53-day, highly-elongated orbits around our Solar System's largest planet. The featured video is from perijove 16, the sixteenth time that Juno has passed near Jupiter since it arrived in mid-2016. Each perijove passes near a slightly different part of Jupiter's cloud tops. This color-enhanced video has been digitally composed from 21 JunoCam still images, resulting in a 125-fold time-lapse. The video begins with Jupiter rising as Juno approaches from the north. As Juno reaches its closest view -- from about 3,500 kilometers over Jupiter's cloud tops -- the spacecraft captures the great planet in tremendous detail. Juno passes light zones and dark belt of clouds that circle the planet, as well as numerous swirling circular storms, many of which are larger than hurricanes on Earth. As Juno moves away, the remarkabledolphin-shaped cloud is visible. After the perijove, Jupiter recedes into the distance, now displaying the unusual clouds that appear over Jupiter's south. To get desired science data, Juno swoops so close to Jupiter that its instruments are exposed to very high levels of radiation.

Slides music - London Philharmonic Orchestra & David Parry : "On the Beautiful Blue Danube, Op. 314"

"On the Beautiful Blue Danube"

Science & Technology - Astronomy picture of the day - 2019 February 3 : An Airglow Fan from Lake to Sky

An Airglow Fan from Lake to Sky Image Credit & Copyright: Dave Lane; Rollover Annotation: Judy Schmidt

Explanation: Why would the sky look like a giant fan? Airglow. The featured intermittent green glow appeared to rise from a lake through the arch of our Milky Way Galaxy, as captured during 2015 next to Bryce Canyon in Utah, USA. The unusual pattern was created by atmospheric gravity waves, ripples of alternating air pressure that can grow with height as the air thins, in this case about 90 kilometers up. Unlike auroras powered by collisions with energetic charged particles and seen at high latitudes, airglow is due to chemiluminescence, the production of light in a chemical reaction. More typically seen near the horizon, airglow keeps the night sky from ever being completely dark.

Short texto - Pinochio

Ha quem lhe chame Pinochio... Eu não ; Pinochio foi um heroi legendario de banda desenhada e, se bem tenha utilisado a mentira na sua existência, não prejudicou qualquer ser.

Ao moderno Socrates, e bem assim "fidalgos" de todos partidos, fodam-lhes o focinho, rebentem-lhes o cu ; façam-nos ajoelharem-se para que nobre e gentilmente recebam a merecida ostia !

Longe de mim FDgP !!!

02-02-2019

JoanMira 

Science & Technology - Astronomy picture of the day - 2019 February 1 : Twin Galaxies in Virgo

"Twin Galaxies in Virgo"  Image Credit & Copyright: CHART32 Team, Processing - Johannes Schedler

Explanation: Spiral galaxy pair NGC 4567 and NGC 4568 share this sharp cosmic vista with lonely elliptical galaxy NGC 4564. All are members of the large Virgo Galaxy Cluster. With their classic spiral arms, dust lanes, and star clusters, the eye-catching spiral pair is also known as the Butterfly Galaxies or the Siamese Twins. Very close together, the galaxy twins don't seem to be too distorted by gravitational tides. Their giant molecular clouds are known to be colliding though and are likely fueling the formation of massive star clusters. The galaxy twins are about 52 million light-years distant, while their bright cores appear separated by about 20,000 light-years. Of course, the spiky foreground stars lie within our own Milky Way.