ASTRONOMY - Quadruple Lunar Halo Over Winter Road

 2022 January 2

Quadruple Lunar Halo Over Winter Road
Image Credit & Copyright: Dani Caxete

Explanation: Sometimes falling ice crystals make the atmosphere into a giant lens causing arcs and halos to appear around the Sun or Moon. One Saturday night in 2012 was just such a time near Madrid, Spain, where a winter sky displayed not only a bright Moon but four rare lunar halos. The brightest object, near the top of the featured image, is the Moon. Light from the Moon refracts through tumbling hexagonal ice crystals into a somewhat rare 22-degree halo seen surrounding the Moon. Elongating the 22-degree arc horizontally is a more rare circumscribed halo caused by column ice crystals. Even more rare, some moonlight refracts through more distant tumbling ice crystals to form a (third) rainbow-like arc 46 degrees from the Moon and appearing here just above a picturesque winter landscape. Furthermore, part of a whole 46-degree circular halo is also visible, so that an extremely rare -- especially for the Moon -- quadruple halo was captured. Far in the background is a famous winter skyscape that includes Sirius, the belt of Orion, and Betelgeuse -- visible between the inner and outer arcs. Halos and arcs typically last for minutes to hours, so if you do see one there should be time to invite family, friends or neighbors to share your unusual lensed vista of the sky.

MUSIC - Herbert Von Karajan & Vienna Phillarmonic Orchestra - Radetzky March

"Radetzky March"

ASTRONOMY - Plane Crossing a Crescent Moon

 2019 February 12

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.

Happy new year !

 

💓😔💓

ASTRONOMY - JWST on the Road to L2

 2021 December 31

JWST on the Road to L2
Image Credit & Copyright: Malcolm Park (North York Astronomical Association)

Explanation: This timelapse gif tracks the James Webb Space Telescope as it streaks across the stars of Orion on its journey to a destination beyond the Moon. Recorded on December 28, 12 consecutive exposures each 10 minutes long were aligned and combined with a subsequent color image of the background stars to create the animation. About 2.5 days after its December 25 launch, JWST cruised past the altitude of the Moon's orbit as it climbed up the gravity ridge from Earth to reach a halo orbit around L2, an Earth-Sun Lagrange point. Lagrange points are convenient locations in space where the combined gravitational attraction of one massive body (Earth) orbiting another massive body (Sun) is in balance with the centripetal force needed to move along with them. So much smaller masses, like spacecraft, will tend to stay there. One of 5 Lagrange points, L2 is about 1.5 million kilometers from Earth directly along the Earth-Sun line. JWST will arrive at L2 on January 23, 29 days after launch. While relaxing in Earth's surface gravity you can follow the James Webb Space Telescope's progress and complicated deployment online.

ASTRONOMY - The Further Tail of Comet Leonard

 2021 December 30

The Further Tail of Comet Leonard
Image Credit & Copyright: Daniele Gasparri

Explanation: Comet Leonard, brightest comet of 2021, is at the lower left of these two panels captured on December 29 in dark Atacama desert skies. Heading for its perihelion on January 3 Comet Leonard's visible tail has grown. Stacked exposures with a wide angle lens (also displayed in a reversed B/W scheme for contrast), trace the complicated ion tail for an amazing 60 degrees, with bright Jupiter shining near the horizon at lower right. Material vaporizing from Comet Leonard's nucleus, a mass of dust, rock, and ices about 1 kilometer across, has produced the long tail of ionized gas fluorescing in the sunlight. Likely flares on the comet's nucleus and buffeting by magnetic fields and the solar wind in recent weeks have resulted in the tail's irregular pinched and twisted appearance. Still days from its closest approach to the Sun, Comet Leonard's activity should continue. The comet is south of the Solar System's ecliptic plane as it sweeps through the southern constellation Microscopium.

RADIOACITIVITé - CRIIRAD - Qu'est-ce que la radioactivité - 1 -

Les atomes qui nous entourent sont composés d’un noyau central autour duquel gravitent des électrons. Lorsque le noyau est instable, pour atteindre un niveau de plus grand équilibre, il se transforme spontanément en émettant des rayonnements très énergétiques. G1 Ce phénomène est appelé radioactivité.

Composition des atomes 

Le noyau contient la quasi-totalité de la masse de l’atome. Les particules qui le composent sont appelées nucléons. On distingue les protons qui portent une charge positive et les neutrons qui sont électriquement neutres. Protons et neutrons ont une masse quasiment identique. 

La cohésion du noyau est assurée par les forces nucléaires qui s’opposent à la répulsion électrique entre protons. Les électrons ont une masse 1 840 fois inférieure à celle des nucléons. Ils portent une charge négative et « gravitent » selon des orbites précisément définies. Dans son état normal, l’atome est électriquement neutre car le nombre d’électrons (-) est égal au nombre de protons (+). La force électromagnétique assure la cohésion de l’atome (les électrons chargés négativement sont attirés par le noyau de charge positive).

CRIIRAD

ASTRONOMY - Giant Storms and High Clouds on Jupiter

 2021 December 29

Giant Storms and High Clouds on Jupiter
Image Credit: NASA/JPL-Caltech/SwRI/MSSS; Processing & License: Kevin M. Gill

Explanation: What and where are these large ovals? They are rotating storm clouds on Jupiter imaged last month by NASA's Juno spacecraft. In general, higher clouds are lighter in color, and the lightest clouds visible are the relatively small clouds that dot the lower oval. At 50 kilometers across, however, even these light clouds are not small. They are so high up that they cast shadows on the swirling oval below. The featured image has been processed to enhance color and contrast. Large ovals are usually regions of high pressure that span over 1000 kilometers and can last for years. The largest oval on Jupiter is the Great Red Spot (not pictured), which has lasted for at least hundreds of years. Studying cloud dynamics on Jupiter with Juno images enables a better understanding of dangerous typhoons and hurricanes on Earth.

ART FRACTAL - Kevin R. Johnson, DR - Un arbre brownien né de sulfate de cuivre

Cet arbre brownien (un cas particulier d'arbre réel aléatoire) est né d'une solution de sulfate de cuivre dans une cellule d'électrodéposition.

© Kevin R. Johnson, DR

SANTE/MEDECINE - Comment mieux dormir - Pas de sport le soir (2)

L’activité sportive est excellente pour la santé, mais mieux vaut programmer son jogging, son cour de gymnastique ou sa séance de natation en matinée ou pendant la pause déjeuner plutôt que le soir. En effet, à partir de 19h, la température du corps commence à baisser, signe que l'organisme se prépare au repos. En augmentant le rythme cardiaque, la pratique sportive maintient une température corporelle plus élevée et réveille l'organisme, perturbant ainsi le rythme biologique. Si votre emploi du temps ne vous permet pas de pratiquer en journée, prenez une douche tiède, et attendez au moins 2 heures après la fin de votre séance pour aller au lit.

Doctissimo

(A suivre...)

Dînez léger

Un bain tiède pour favoriser l’endormissement

Respectez votre sommeil

Attention aux écrans

On oublie les soucis

La chambre, un endroit pour dormir... et faire l'amour

Une chambre à la bonne température

Du noir et du silence

Un bon matelas pour un sommeil au top