ASTRONOMY - Quadrantids of the North

 2022 January 8

Quadrantids of the North
Image Credit & Copyright: Cheng Luo

Explanation: Named for a forgotten constellation, the Quadrantid Meteor Shower puts on an annual show for planet Earth's northern hemisphere skygazers. The shower's radiant on the sky lies within the old, astronomically obsolete constellation Quadrans Muralis. That location is not far from the Big Dipper, at the boundaries of the modern constellations Bootes and Draco. In fact north star Polaris is just below center in this frame and the Big Dipper asterism (known to some as the Plough) is above it, with the meteor shower radiant to the right. Pointing back toward the radiant, Quadrantid meteors streak through the night in the panoramic skyscape, a composite of images taken in the hours around the shower's peak on January 4, 2022. Arrayed in the foreground are radio telescopes of the Chinese Spectral Radioheliograph, Mingantu Observing Station, Inner Mongolia, China. A likely source of the dust stream that produces Quadrantid meteors was identified in 2003 as an asteroid.

ASTRONOMY - Ecstatic Solar Eclipse

 2022 January 7

Ecstatic Solar Eclipse
Image Credit & Copyright: Annie Schmidt (Point Blue Conservation Science)

Explanation: A male Adelie penguin performed this Ecstatic Vocalization in silhouette during the December 4 solar eclipse, the final eclipse of 2021. Of course his Ecstatic Vocalization is a special display that male penguins use to claim their territory and advertise their condition. This penguin's territory, at Cape Crozier Antarctica, is located in one of the largest Adelie penguin colonies. The colony has been studied by researchers for over 25 years. From there, last December's eclipse was about 80 percent total when seen at its maximum phase as the Moon's shadow crossed planet Earth's southernmost continent.

MICROPHOTOGRAPHIE - Marek Mis - Lorsque la vitamine C invite à la rêverie

Des cristaux d'acide ascorbique -- de la vitamine C, en d'autres mots --, une lumière polarisée, un champ sombre et un grossissement de 200 fois. Voilà pour le côté technique du cliché.

Mais, devant cette mosaïque microscopique, pourquoi ne pas nous laisser aller à un peu de rêverie ? Comme lorsque nous étions enfants et que, couchés dans l'herbe, nous cherchions des formes particulières dans les nuages. Les spécialistes appellent cela la paréidolie. Une sorte d'illusion d'optique qui nous permet d'associer un stimulus visuel informe et ambigu à un élément clair et identifiable.

Prêts à tenter l'expérience ici ? Alors, posez-vous quelques instants devant cette image et laissez tout simplement la magie opérer. Vous n'y voyez rien d'autre que les reliefs d'un sol couvert de glaces ? C'est déjà un premier pas. Maintenant, ouvrez grande la porte à votre imaginaire. Et regardez plus particulièrement le côté gauche du cliché. N'y découvrez-vous pas ce qui ressemble à un étrange dinosaure ? Vers le centre désormais, le profil à la mode vaguement cubiste d'une femme assise ? Tout contre sa nuque, la tête d'un loup à l'air plutôt inoffensif ? Et peut-être encore beaucoup d'autres...

Cliché réalisé à l'aide d'un microscope Olympus BH-2 et d'un appareil Pentax K5. © Marek Miś. Tous droits réservés

ASTRONOMY - The Last Days of Venus as the Evening Star

 2022 January 6

The Last Days of Venus as the Evening Star
Image Credit & Copyright: Tamas Ladanyi (TWAN)

Explanation: That's not a young crescent Moon posing behind cathedral towers after sunset. It's Venus in a crescent phase. About 40 million kilometers away and about 2 percent illuminated by sunlight, it was captured with camera and telephoto lens in this series of exposures as it set in western skies on January 1 from Veszprem, Hungary. The bright celestial beacon was languishing in the evening twilight, its days as the Evening Star coming to a close as 2022 began. But it was also growing larger in apparent size and becoming an ever thinner crescent in telescopic views. Heading toward a (non-judgemental) inferior conjunction, the inner planet will be positioned between Earth and Sun on January 9 and generally lost from view in the solar glare. A crescent Venus will soon reappear though. Rising in the east by mid-month just before the Sun as the brilliant Morning Star.

AERONAUTIQUE - Avions de légende - Le Lockheed SR-71 Blackbird

 

Le SR-71 Blackbird, de la firme Lockheed, est un avion supersonique employé au cours de la guerre froide par la CIA, le département d'État américain, la Nasa ainsi que l'US Navy pour des missions de surveillance et d'espionnage photographique. Il fut en service entre 1968 et 1990. Cet avion au fuselage futuriste est également très présent dans l'imaginaire collectif à travers de nombreux films, séries télévisées et jeux vidéo qui ont emprunté son image.

© mashleymorgan, CC by-nc 2.0

SANTE/MEDECINE - Comment mieux dormir - 3. Dînez léger

Une digestion difficile contrarie le sommeil, alors évitez les dîners lourds avant de filer au lit. Proscrivez la viande rouge, les plats épicés. Préférez des crudités, du pain blanc, des pâtes, du poisson et des légumes, et tous les produits laitiers qui contiennent du tryptophane, un acide-aminé précurseur de la sérotonine, hormone de la tranquillité et de l'endormissement ! Enfin, dînez le plus tôt possible (dans l'idéal, deux heures avant le coucher) car la digestion augmente la température corporelle.

Doctissimo

ASTRONOMY - A Year of Sunrises

2022 January 5

A Year of Sunrises
Image Credit & Copyright: Luca Vanzella

Explanation: Does the Sun always rise in the same direction? No. As the months change, the direction toward the rising Sun changes, too. The featured image shows the direction of sunrise every month during 2021 as seen from the city of Edmonton, Alberta, Canada. The camera in the image is always facing due east, with north toward the left and south toward the right. As shown in an accompanying video, the top image was taken in 2020 December, while the bottom image was captured in 2021 December, making 13 images in total. Although the Sun always rises in the east in general, it rises furthest to the south of east on the December solstice, and furthest north of east on the June solstice. In many countries, the December Solstice is considered an official change in season: for example the first day of winter in the North. Solar heating and stored energy in the Earth's surface and atmosphere are near their lowest during winter, making the winter season the coldest of the year.

ASTRONOMY - Moons behind rings of Saturn

 2022 January 4

Moons Beyond Rings at Saturn
Image Credit: NASA, ESA, JPL, Cassini Imaging Team

Explanation: What's happened to that moon of Saturn? Nothing -- Saturn's moon Rhea is just partly hidden behind Saturn's rings. In 2010, the robotic Cassini spacecraft then orbiting Saturn took this narrow-angle view looking across the Solar System's most famous rings. Rings visible in the foreground include the thin F ring on the outside and the much wider A and B rings just interior to it. Although it seems to be hovering over the rings, Saturn's moon Janus is actually far behind them. Janus is one of Saturn's smaller moons and measures only about 180 kilometers across. Farther out from the camera is the heavily cratered Rhea, a much larger moon measuring 1,500 kilometers across. The top of Rhea is visible only through gaps in the rings. After more than a decade of exploration and discovery, the Cassini spacecraft ran low on fuel in 2017 and was directed to enter Saturn's atmosphere, where it surely melted.

ASTRONOMY - Comet Leonard's Long Tail

 2022 January 3

Comet Leonard's Long Tail
Image Credit & Copyright: Jan Hattenbach

Explanation: You couldn't see Comet Leonard’s extremely long tail with a telescope — it was just too long. You also couldn't see it with binoculars — still too long. Or with your eyes -- it was too dim. Or from a city — the sky was too bright. But from a dark location with a low horizon — your camera could. And still might -- if the comet survives today's closest encounter with the Sun, which occurs between the orbits of Mercury and Venus. The featured picture was created from two deep and wide-angle camera images taken from La Palma in the Canary Islands of Spain late last month. Afterwards, if it survives, what is left of Comet Leonard's nucleus will head out of our Solar System, never to return.

ASTRONOMIE - Tout comprendre sur le soleil

Le Soleil