ASTRONOMY - Perihelion to Aphelion

 2021 July 8

Perihelion to Aphelion
Image Credit & Copyright: Richard Jaworski

Explanation: Aphelion for 2021 occurred on July 5th. That's the point in Earth's elliptical orbit when it is farthest from the Sun. Of course, the distance from the Sun doesn't determine the seasons. Those are governed by the tilt of Earth's axis of rotation, so July is still summer in the north and winter in the southern hemisphere. But it does mean that on July 5 the Sun was at its smallest apparent size when viewed from planet Earth. This composite neatly compares two pictures of the Sun, both taken with the same telescope and camera. The left half was captured close to the date of the 2021 perihelion (January 2), the closest point in Earth's orbit. The right was recorded just before the aphelion in 2021. Otherwise difficult to notice, the change in the Sun's apparent diameter between perihelion and aphelion amounts to a little over 3 percent.

ASTRONOMY - Saturn and Six Moons

 2021 July 6

Saturn and Six Moons
Image Credit & Copyright: Mohammad Ranjbaran; MR Thanks: Amir Ehteshami

Explanation: How many moons does Saturn have? So far 82 have been confirmed, the smallest being only a fraction of a kilometer across. Six of its largest satellites can be seen here in a composite image with 13 short exposure of the bright planet, and 13 long exposures of the brightest of its faint moons, taken over two weeks last month. Larger than Earth's Moon and even slightly larger than Mercury,Saturn's largest moon Titan has a diameter of 5,150 kilometers and was captured making nearly a complete orbit around its ringed parent planet. Saturn's first known natural satellite, Titan was discovered in 1655 by Dutch astronomer Christiaan Huygens, in contrast with several newly discovered moons announced in 2019. The trail on the far right belongs to Iapetus, Saturn's third largest moon. The radius of painted Iapetus' orbit is so large that only a portion of it was captured here. Saturn leads Jupiter across the night sky this month, rising soon after sunset toward the southeast, and remaining visible until dawn.

ASTRONOMY - Simulation: Formation of the First Stars

 2021 June 30

Simulation: Formation of the First Stars
Video Credit: Harley Katz (U. Oxford) et al.

Explanation: How did the first stars form? To help find out, the SPHINX computer simulation of star formation in the very early universe was created, some results of which are shown in the featured video. Time since the Big Bang is shown in millions of years on the upper left. Even 100 million years after the Big Bang, matter was spread too uniformly across the cosmos for stars to be born. Besides background radiation, the universe was dark. Soon, slight matter clumps rich in hydrogen gas begin to coalesce into the first stars. In the time-lapse video, purple denotes gas, white denotes light, and gold shows radiation so energetic that it ionizes hydrogen, breaking it up into charged electrons and protons. The gold-colored regions also track the most massive stars that die with powerful supernovas. The inset circle highlights a central region that is becoming a galaxy. The simulation continues until the universe was about 550 million years old. To assess the accuracy of the SPHINX simulations and the assumptions that went into them, the results are not only being compared to current deep observations, but will also be compared with more direct observations of the early universe planned with NASA's pending James Webb Space Telescope.

INSECTES - Le moustique-tigre

Les premières chaleurs de l’été sont synonymes du retour d’un insecte plutôt désagréable : le moustique. Parmi les 3.000 espèces existantes, le moustique-tigre, ou Aedes albopictus, est l’une des plus redoutées.

En effet, le moustique-tigre est originaire d’Asie du Sud-Est mais il s'est adapté rapidement à des climats et des régions différents. Il est désormais présent sur tous les continents sauf l’Antarctique. En France, il s’est implanté durablement dans les trois quarts des départements métropolitains.

Futura Sciences

ASTRONOMY - The Face on Mars

 2021 July 4

The Face on Mars
Image Credit: NASA, Viking 1 Orbiter

Explanation: Wouldn't it be fun if clouds were castles? Wouldn't it be fun if the laundry on the bedroom chair was a superhero? Wouldn't it be fun if rock mesas on Mars were interplanetary monuments to the human face? Clouds, though, are floating droplets of water and ice. Laundry is cotton, wool, or plastic, woven into garments. Famous Martian rock mesas known by names like the Face on Mars appear quite natural when seen more clearly on better images. Is reality boring? Nobody knows why some clouds make rain. Nobody knows if life ever developed on Mars. Nobody knows why the laundry on the bedroom chair smells like root beer. Scientific exploration can not only resolve mysteries, but uncover new knowledge, greater mysteries, and yet deeper questions. As humanity explores our universe, perhaps fun -- through discovery -- is just beginning.

SANTé/MéDECINE - L'alcool et le foie

Les discours anti-alcool, ça fait plusieurs années que les professionnels de la santé ne cessent d’en faire. Pourtant, le nombre de buveurs continue de grimper et ils sont de plus en plus jeunes. Si l’alcool en soi ne pose pas problème, c’est son excès qui est vivement pointé du doigt en raison de son impact sur la santé notamment le foie, et vous allez vite comprendre pourquoi.

Les toxines d’alcool annihilent le filtre hépatique

Le foie est, avec les reins, l’un des organes qui s’assurent d’assainir notre organisme. L’un de ses rôles est de débarrasser notre organisme des toxines en filtrant le sang et cette fonction de filtre, c’est à cellules que le foie le doit.

Or, la capacité du foie à filtrer les toxines d’alcool est limitée. Plus vous buvez, plus vous acculez votre foie. Ce qui dégrade la capacité à filtrer de ce dernier, conduisant à une inflammation, puis à la mort des cellules hépatiques.

Conséquences de la dégradation du filtre hépatique

Malheureusement, la dégradation des cellules du foie n’est que le début d’un long processus de dégradation. À termes, les buveurs chroniquent et les alcooliques encore plusieurs conséquences graves à savoir :

• La fibrose qui est une accumulation de tissu cicatriciel dans le foie
• La cirrhose qui se manifeste par un dysfonctionnement total des fonctions hépatiques.

Il en résulte l’envahissement de votre organisme par les toxiques que le foie n’arrive plus à éliminer.

ASTRONOMY - Along the Milky Way

 2021 July 3

Along the Milky Way
Image Credit & Copyright: Rolf Weisenfeld

Explanation: You can't walk along the Milky Way. Still, under a dark sky you can explore it. To the eye the pale luminous trail of light arcing through the sky on a dark, moonless night does appear to be a path through the heavens. The glowing celestial band is the faint, collective light of distant stars cut by swaths of obscuring interstellar dust clouds. It lies along the plane of our home galaxy, so named because it looks like a milky way. Since Galileo's time, the Milky Way has been revealed to telescopic skygazers to be filled with congeries of innumerable stars and cosmic wonders.

ASTRONOMY - AR2835: Islands in the Photosphere

 2021 July 2

AR2835: Islands in the Photosphere
Image Credit & Copyright: Michael Teoh, Heng Ee Observatory, Penang, Malaysia

Explanation: Awash in a sea of incandescent plasma and anchored in strong magnetic fields, sunspots are planet-sized dark islands in the solar photosphere, the bright surface of the Sun. Found in solar active regions, sunspots look dark only because they are slightly cooler though, with temperatures of about 4,000 kelvins compared to 6,000 kelvins for the surrounding solar surface. These sunspots lie in active region AR2835. The largest active region now crossing the Sun, AR2835 is captured in this sharp telescopic close-up from July 1 in a field of view that spans about 150,000 kilometers or over ten Earth diameters. With powerful magnetic fields, solar active regions are often responsible for solar flares and coronal mass ejections, storms which affect space weather near planet Earth.

ASTRONOMY - Perseverance Selfie with Ingenuity

 2021 July 1

Perseverance Selfie with Ingenuity
Image Credit: NASA, JPL-Caltech, MSSS

Explanation: On sol 46 (April 6, 2021) the Perseverance rover held out a robotic arm to take its first selfie on Mars. The WATSON camera at the end of the arm was designed to take close-ups of martian rocks and surface details though, and not a quick snap shot of friends and smiling faces. In the end, teamwork and weeks of planning on Mars time was required to program a complex series of exposures and camera motions to include Perseverance and its surroundings. The resulting 62 frames were composed into a detailed mosiac, one of the most complicated Mars rover selfies ever taken. In this version of the selfie, the rover's Mastcam-Z and SuperCam instruments are looking toward WATSON and the end of the rover's outstretched arm. About 4 meters (13 feet) from Perseverance is a robotic companion, the Mars Ingenuity helicopter.

PRATIQUE - Enfin une Astuce Pour Que la Grille du Barbecue ne colle plus

Vous en avez assez que de la nourriture reste collée sur la grille du barbecue ? Que ça soit du poisson, comme les sardines, ou de la viande, ça s'accroche toujours sur la grille. Résultat, il faut frotter bien fort pour nettoyer la grille, sinon elle s'encrasse rapidement. Heureusement, il existe un truc incroyable pour que les aliments ne restent plus accrochés sur le bbq. L'astuce est de frotter un oignon sur la grille avant de faire cuire les aliments.