ASTRONOMY - Messier 88

 2022 December 28

Messier 88
Image Credit & Copyright: Adam Block, Mt. Lemmon SkyCenter, U. Arizona

Explanation: Charles Messier described the 88th entry in his 18th century catalog of Nebulae and Star Clusters as a spiral nebula without stars. Of course the gorgeous M88 is now understood to be a galaxy full of stars, gas, and dust, not unlike our own Milky Way. In fact, M88 is one of the brightest galaxies in the Virgo Galaxy Cluster some 50 million light-years away. M88's beautiful spiral arms are easy to trace in this sharp cosmic portait. The arms are lined with young blue star clusters, pink star-forming regions, and obscuring dust lanes extending from a yellowish core dominated by an older population of stars. Spiral galaxy M88 spans over 100,000 light-years.

ASTRONOMY - A Full Circle Rainbow over Norway

 2022 December 27

A Full Circle Rainbow over Norway
Image Credit & Copyright: Lukas Moesch

Explanation: Have you ever seen an entire rainbow? From the ground, typically, only the top portion of a rainbow is visible because directions toward the ground have fewer raindrops. From the air, though, the entire 360-degree circle of a rainbow is more commonly visible. Pictured here, a full-circle rainbow was captured over the Lofoten Islands of Norway in September by a drone passing through a rain shower. An observer-dependent phenomenon primarily caused by the internal reflection of sunlight by raindrops, the rainbow has a full diameter of 84 degrees. The Sun is in the exact opposite direction from the rainbow's center. As a bonus, a second rainbow that was more faint and color-reversed was visible outside the first.

ASTRONOMY - NGC 6164: Dragon's Egg Nebula and Halo

 2022 December 26

NGC 6164: Dragon's Egg Nebula and Halo
Image Credit & Copyright: Russell Croman

Explanation: The star at the center created everything. Known as the Dragon's Egg, this star -- a rare, hot, luminous O-type star some 40 times as massive as the Sun -- created not only the complex nebula (NGC 6164) that immediately surrounds it, but also the encompassing blue halo. Its name is derived, in part, from the region's proximity to the picturesque NGC 6188, known as the fighting Dragons of Ara. In another three to four million years the massive star will likely end its life in a supernova explosion. Spanning around 4 light-years, the nebula itself has a bipolar symmetry making it similar in appearance to more common planetary nebulae - the gaseous shrouds surrounding dying sun-like stars. Also like many planetary nebulae, NGC 6164 has been found to have an extensive, faint halo, revealed in blue in this deep telescopic image of the region. Expanding into the surrounding interstellar medium, the material in the blue halo was likely expelled from an earlier active phase of the O-star. NGC 6164 lies 4,200 light-years away in the southern constellation of the Carpenter's Square (Norma).

BIOMIMETISME - La Nature inspire la Science - La cape d'invisibilité des seiches inspire les roboticiens

La cape d'invisibilité d'Harry Potter semble bien pratique. Peut-être que l'auteure, J.K Rowling, s'est inspirée des seiches pour l'inventer. Si les seiches ne disparaissent pas, elles sont capables de se fondre dans leur environnement, tout comme les pieuvres, pour devenir pratiquement invisibles. Cela est possible grâce à leur peau qui est constituée comme un feuillet de trois couches de cellules pigmentaires : les leucophores qui prennent une teinte blanche, les iridophores qui réfléchissent la lumière et prennent un aspect iridescent, et enfin, une dernière couche de chromatophores qui peuvent changer de couleur rapidement.

Cette peau de « caméléon » a inspiré les scientifiques du milieu de la robotique : en 2017, une équipe a conçu une cape d'invisibilité en s'inspirant de la peau des seiches. La peau synthétique en silicone peut être programmée pour réaliser des formes et des motifs complexes.

© Hans Hillewaert, Wikimedia Commons, CC by-sa 4.0

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MERVEILLEUX MONDE SOUS-MARIN - Épave du SS Yongala - Australie

Crédit photo: 4 hours 1000 places

Au large de l’Etat du Queensland en Australie, on peut retrouver l’épave du SS Yongala, un paquebot qui a coulé en 1911 après avoir été touché par un cyclone. Un lieu célèbre pour la plongée, pour admirer les vestiges du navire découvert en 1958, et le biodiversité sous-marine locale.

GenerationVoyage

ASTRONOMY - Geminids and the Mittens

 2022 December 25

Geminids and the Mittens
Image Credit & Copyright: Chuck Derus

Explanation: Asteroid 3200 Phaethon's annual gift to planet Earth always arrives in December. Otherwise known as the Geminid meteor shower, the source of the meteroid stream is dust shed along the orbit of the mysterious asteroid. Near the December 13/14 peak of the shower's activity, geminid meteors are captured in this night skyscape, composited from 22 images of starry sky taken before the moon rose over Monument Valley in the American southwest. The bright stars near the position of the shower's radiant are the constellation Gemini's twin stars Castor (blue) and Pollux (yellow). As Earth sweeps through the dusty stream, the parallel meteor trails appear to radiate from a point on the sky in Gemini due to perspective, and so the yearly shower is named for the constellation. From the camera's perspective, this view of three prominent buttes across Monument Valley also suggests appropriate names for two of them. The third one is called Merrick Butte.

MUSICA - Luciano Pavarotti - Ave Maria (Scubert)

"Ave Maria"

ASTRONOMY - Comet 2022 E3 (ZTF)

 2022 December 24

Comet 2022 E3 (ZTF)
Image Credit & Copyright: Dan Bartlett

Explanation: Comet C/2022 E3 (ZTF) was discovered by astronomers using the wide-field survey camera at the Zwicky Transient Facility this year in early March. Since then the new long-period comet has brightened substantially and is now sweeping across the northern constellation Corona Borealis in predawn skies. It's still too dim to see without a telescope though. But this fine telescopic image from December 19 does show the comet's brighter greenish coma, short broad dust tail, and long faint ion tail stretching across a 2.5 degree wide field-of-view. On a voyage through the inner Solar System comet 2022 E3 will be at perihelion, its closest to the Sun, in the new year on January 12 and at perigee, its closest to our fair planet, on February 1. The brightness of comets is notoriously unpredictable, but by then C/2022 E3 (ZTF) could become only just visible to the eye in dark night skies.

ASTRONOMY - Cassini Looks Out from Saturn

 2022 December 23

Cassini Looks Out from Saturn
Image Credit: NASA, JPL-Caltech, Space Science Institute

Explanation: This is what Saturn looks like from inside the rings. In 2017, for the first time, NASA directed the Cassini spacecraft to swoop between Saturn and its rings. During the dive, the robotic spacecraft took hundreds of images showing unprecedented detail for structures in Saturn's atmosphere. Looking back out, however, the spacecraft was also able to capture impressive vistas. In the featured image, taken a few hours before closest approach, Saturn's unusual northern hexagon is seen surrounding the North Pole. Saturn's B ring is the closest visible, while the dark Cassini Division separates B from the outer A. A close inspection will find the two small moons that shepherd the F-ring, the farthest ring discernable. A few months after this image was taken -- and after more than a decade of exploration and discovery -- the Cassini spacecraft ran low on fuel and was directed to enter Saturn's atmosphere, where it surely melted.

BIOMIMETISME - LA SCIENCE S'INSPIRE DE LA NATURE - De la peau de requin sur des avions

La peau des requins est aussi une source d'inspiration. Si cela ne saute pas yeux, elle est en réalité recouverte de millions de petites « dents » appelées denticules cutanées. Grâce à cela, le requin améliore sa glisse dans l'eau et cette peau permet à certaines espèces, comme le requin mako, de faire des pointes de vitesse à environ 60 km/h.

Les équipementiers sportifs se sont inspirés de la peau des squales pour concevoir une combinaison de natation pour les nageurs professionnels. La collection Fastskin de Speedo, notamment, copie la peau des requins mako. Airbus a aussi recouvert certains de ses avions de revêtement strié qui imite les denticules cutanées.

© Stevelaycock21, Wikimedia Commons, CC by-sa 4.0

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