ASTRONOMY - Moon Pi and Mountain Shadow

 2024 March 14

Moon Pi and Mountain Shadow
Image Credit & Copyright: Daniel Lopez (El Cielo de Canarias)

Explanation: What phase of the Moon is 3.14 radians from the Sun? The Full Moon, of course. Even though the Moon might look full for several days, the Moon is truly at its full phase when it is Pi radians (aka 180 degrees) from the Sun in ecliptic longitude. That's opposite the Sun in planet Earth's sky. Rising as the Sun set on March 9, 2020, only an hour or so after the moment of its full phase, this orange tinted and slightly flattened Moon still looked full. It was photographed opposite the setting Sun from Teide National Park on the Canary Island of Tenerife. Also opposite the setting Sun, seen from near the Teide volcano peak about 3,500 meters above sea level, is the mountain's rising triangular shadow extending into Earth's dense atmosphere. Below the distant ridge line on the left are the white telescope domes of Teide Observatory. Again Pi radians from the Sun, on March 25 the Full Moon will dim slightly as it glides through Earth's outer shadow in a penumbral lunar eclipse.

SANTé/MEDECINE - HISTOIRE - 1561 : Ambroise Paré, le père de la chirurgie moderne

Considéré comme le père de la chirurgie moderne, Ambroise Paré est l'inventeur d'instruments chirurgicaux. Il a mis au point la ligature des artères, qui remplacera la cautérisation. En 1561 et 1562, Ambroise Paré publie un ouvrage intitulé Anatomie universelle du corps humain.

© William Holl

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ASTRONOMY - The Seagull Nebula

 2024 March 13

The Seagull Nebula
Credit & Copyright: Gianni Lacroce

Explanation: A broad expanse of glowing gas and dust presents a bird-like visage to astronomers from planet Earth, suggesting its popular moniker: the Seagull Nebula. This portrait of the cosmic bird covers a 1.6-degree wide swath across the plane of the Milky Way, near the direction of Sirius, the alpha star of the constellation of the Big Dog (Canis Major). Of course, the region includes objects with other catalog designations: notably NGC 2327, a compact, dusty emission and reflection nebula with an embedded massive star that forms the bird's head. Dominated by the reddish glow of atomic hydrogen, the complex of gas and dust clouds with bright young stars spans over 100 light-years at an estimated 3,800 light-year distance.

ASTRONOMIE - Exoplanète

Une exoplanète, aussi connue sous le nom de planète extrasolaire, est une planète ne tourne pas autour du Soleil mais qui orbite autour d'une étoile en dehors de notre Système solaire. Le préfixe exo signifie « extérieur », donc une exoplanète est essentiellement une planète extérieure à notre propre Système solaire.

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ASTRONOMY - A Galaxy-Shaped Rocket Exhaust Spiral

 2024 March 12

A Galaxy-Shaped Rocket Exhaust Spiral
Credit & Copyright: Seung Hye Yang

Explanation: What's that over the horizon? What may look like a strangely nearby galaxy is actually a normal rocket's exhaust plume -- but unusually backlit. Although the SpaceX Falcon 9 rocket was launched from Cape Canaveral in Florida, USA, its burned propellant was visible over a much wider area, with the featured photograph being taken from Akureyri, Iceland. The huge spaceship was lifted off a week ago, and the resulting spectacle was captured soon afterward with a single 10-second smartphone exposure, before it quickly dissipated. Like noctilucent clouds, the plume's brightness is caused by the Twilight Effect, where an object is high enough to be illuminated by the twilight Sun, even when the observer on the ground experiences the darkness of night. The spiral shape is likely caused by high winds pushing the expelled gas into the shape of a corkscrew, which, when seen along the trajectory, looks like a spiral. Stars and faint green and red aurora appear in the background of this extraordinary image.

SANTé/MEDECINE - HISTOIRE - La saignée

La saignée était une technique employée pour éliminer les maladies par le prélèvement de sang. Elle est préconisée par les défenseurs de la théorie des humeurs (Hippocrate), mais progressivement abandonnée.

© DR

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SANTé/MEDECINE - L'IRM pour mesurer le flux sanguin

À partir de données récoltées depuis une analyse IRM d'un organe, il est possible d'en déduire un certain nombre de détails. Ici, il s'agit d'une simulation du flux sanguin dans une artère carotide. En bleu, les zones où le sang s'écoule mal, à cause d'une plaque d'athérome bouchant le vaisseau.

© CNRS Photothèque, Loïc Boussel

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ASTRONOMY - A Full Plankton Moon

 2024 March 11

A Full Plankton Moon
Credit & Copyright: Petr Horálek / Institute of Physics in Opava

Explanation: What glows in the night? This night featured a combination of usual and unusual glows. Perhaps the most usual glow was from the Moon, a potentially familiar object. The full Moon's nearly vertical descent results from the observer being near Earth's equator. As the Moon sets, air and aerosols in Earth's atmosphere preferentially scatter out blue light, making the Sun-reflecting satellite appear reddish when near the horizon. Perhaps the most unusual glow was from the bioluminescent plankton, likely less familiar objects. These microscopic creatures glow blue, it is thought, primarily to surprise and deter predators. In this case, the glow was caused primarily by plankton-containing waves crashing onto the beach. The image was taken on Soneva Fushi Island, Maldives just over one year ago.

ASTRONOMY - A Total Eclipse at the End of the World

 2024 March 10

A Total Eclipse at the End of the World
Image Credit & Copyright: Fred Bruenjes (moonglow.net)

Explanation: Would you go to the end of the world to see a total eclipse of the Sun? If you did, would you be surprised to find someone else there already? In 2003, the Sun, the Moon, Antarctica, and two photographers all lined up in Antarctica during an unusual total solar eclipse. Even given the extreme location, a group of enthusiastic eclipse chasers ventured near the bottom of the world to experience the surreal momentary disappearance of the Sun behind the Moon. One of the treasures collected was the featured picture -- a composite of four separate images digitally combined to realistically simulate how the adaptive human eye saw the eclipse. As the image was taken, both the Moon and the Sun peeked together over an Antarctic ridge. In the sudden darkness, the magnificent corona of the Sun became visible around the Moon. Quite by accident, another photographer was caught in one of the images checking his video camera. Visible to his left are an equipment bag and a collapsible chair. A more easily visible solar eclipse will occur in just under four weeks and be visible from a long, thin swath of North America.

SANTé/MEDECINE - HISTOIRE - L'Égypte antique et la momification

La momification est un processus permettant de conserver des corps pendant des milliers d'années. Le corps était éviscéré, séché au soleil, enduit d'huiles et enfin entouré de bandelettes. Les connaissances du corps humain étaient déjà développées durant l'Égypte antique.

Cette momie égyptienne date de l'époque ptolémaïque, (IIIe - IIe siècle avant J.-C.). Elle est conservée au musée du Louvre, département des antiquités égyptiennes, N 2627.

© Dada by-sa 3.0

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