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04/04/2024

SANTé/MEDECINE - HISTOIRE - 1882 : découverte du bacille de Koch et début de la bactériologie


Robert Koch, un médecin allemand, découvrit en 1882 l'agent responsable de la tuberculose, le bacille de Koch (Mycobacterium tuberculosis), ce qui ouvrit la voie à la bactériologie.

Il obtint le prix Nobel de médecine et de physiologie en 1905. Il découvrit également le bacille du choléra (1883) et formula les postulats de Koch qui permettent de déterminer si une maladie est due à un micro-organisme.

© AJC1, Flickr, CC by-nc 2.0
FuturaSciences

INVENTEURS TUéS PAR LEURS CREATIONS - Alexander Bogdanov


Alexander Bogdanov, médecin russe renommé, philosophe, économiste, écrivain de science-fiction et révolutionnaire, développe un intérêt soudain pour le rajeunissement humain qu'il croit possible par la transfusion sanguine. Dans l'espoir d'accéder à l'éternelle jeunesse et à la régénération des lésions corporelles, il entreprend 11 transfusions sanguines, grâce auxquelles il note, selon lui, une amélioration de la vue et une réduction de la calvitie. On crie au miracle ? Pas tout à fait, Bogdanov est mort en 1928, après s'être transfusé le sang d'un étudiant qui avait la tuberculose et le paludisme

© Domaine public. Montuno, Flickr, CC by-sa 2.0
FuturaSciences

ASTRONOMY - Comet Pons-Brooks at Night

 2024 April 4

See Explanation.  Clicking on the picture will download
 the highest resolution version available.

Comet Pons-Brooks at Night
Image Credit & CopyrightDan Bartlett`

Explanation: In dark evening skies over June Lake, northern hemisphere, planet Earth, Comet 12P/Pons-Brooks stood just above the western horizon on March 30. Its twisted turbulent ion tail and diffuse greenish coma are captured in this two degree wide telescopic field of view along with bright yellowish star Hamal also known as Alpha Arietis. Now Pons-Brooks has moved out of the northern night though, approaching perihelion on April 21. On April 8 you might still spot the comet in daytime skies. But to do it, you will have to stand in the path of totality and look away from the spectacle of an alluring solar corona and totally eclipsed Sun.

03/04/2024

SANTé/MEDECINE - Le fonctionnement de l'oeil humain - Les différents muscles (vus de face)


Différents muscles permettent les mouvements de l'œil :
le muscle droit supérieur ;
le muscle droit inférieur ;
le muscle droit latéral ;
le muscle droit médial ;
le muscle oblique inférieur ;
le muscle oblique supérieur.

Le muscle oblique inférieur permet, par exemple, de déplacer l'œil vers le haut. Ces muscles sont innervés.

© Patrick J. Lynch, CC by 2.5
FuturaSciences

ASTRONOMY - Unusual Nebula Pa 30

 2024 April 3

A nebula is shown that appears like a firework. Radial
filaments connect a glowing halo to a star in the center
that appears as a blue dot. 
Please see the explanation for more detailed information.

Unusual Nebula Pa 30
Image Credit: NASAESAUSAFNSF;
Processing: G. Ferrand (U. Manitoba), J. English (U. Manitoba), R. A. Fesen (Dartmouth), C. Treyturik (U. Manitoba);
Text: G. Ferrand & J. English

Explanation: What created this unusual celestial firework? The nebula, dubbed Pa 30, appears in the same sky direction now as a bright "guest star" did in the year 1181. Although Pa 30's filaments look similar to that created by a nova (for example GK Per), and a planetary nebula (for example NGC 6751), some astronomers now propose that it was created by a rare type of supernova: a thermonuclear Type Iax, and so is (also) named SN 1181. In this model, the supernova was not the result of the detonation of a single star, but rather a blast that occurred when two white dwarf stars spiraled together and merged. The blue dot in the center is hypothesized to be a zombie star, the remnant white dwarf that somehow survived this supernova-level explosion. The featured image combines images and data obtained with infrared (WISE), visible (MDMPan-STARRS), and X-ray (ChandraXMM) telescopes. Future observations and analyses may tell us more.

02/04/2024

SANTé/MEDECINE - HISTOIRE - 1847 : l'hygiène en médecine avec Semmelweis


Ignace Philippe Semmelweis, un médecin obstétricien austro-hongrois, découvrit que le lavage des mains diminuait le nombre des décès suite aux fièvres puerpérales des femmes après l'accouchement.

FuturaSciences

ASTRONOMY - Detailed View of a Solar Eclipse Corona

 2024 April 2

The Sun is shown during a total solar eclipse. Accentuated
is the expansive corona of the Sun, which is shown streaming
out in all directions. 
Please see the explanation for more detailed information.

Detailed View of a Solar Eclipse Corona
Image Credit & Copyright: Phil Hart

Explanation: Only in the fleeting darkness of a total solar eclipse is the light of the solar corona easily visible. Normally overwhelmed by the bright solar disk, the expansive corona, the sun's outer atmosphere, is an alluring sight. But the subtle details and extreme ranges in the corona's brightness, although discernible to the eye, are notoriously difficult to photograph. Pictured here, however, using multiple images and digital processing, is a detailed image of the Sun's corona taken during the April 20, 2023 total solar eclipse from Exmouth, Australia. Clearly visible are intricate layers and glowing caustics of an ever changing mixture of hot gas and magnetic fields. Bright looping prominences appear pink just around the Sun's limb. A similar solar corona might be visible through clear skies in a narrow swath across the North America during the total solar eclipse that occurs just six days from today

01/04/2024

ASTRONOMY - Swirling Magnetic Field around Our Galaxy's Central Black Hole

 2024 April 1

A donut-shaped orange figure is seen with lines
extending along the emission in a swirling pattern.
Please see the explanation for more detailed information.

Swirling Magnetic Field around Our Galaxy's Central Black Hole
Image Credit: EHT Collaboration

Explanation: What's happening to the big black hole in the center of our galaxy? It is sucking in matter from a swirling disk -- a disk that is magnetized, it has now been confirmed. Specifically, the black hole's accretion disk has recently been seen to emit polarized light, radiation frequently associated with a magnetized sourcePictured here is a close-up of Sgr A*, our Galaxy's central black hole, taken by radio telescopes around the world participating in the Event Horizon Telescope (EHT) Collaboration. Superposed are illustrative curved lines indicating polarized light likely emitted from swirling magnetized gas that will soon fall into the 4+ million mass central black hole. The central part of this image is likely dark because little light-emitting gas is visible between us and the dark event horizon of the black hole. Continued EHT monitoring of this and M87's central black hole may yield new clues about the gravity of black holes and how infalling matter creates disks and jets.

31/03/2024

ASTRONOMY - Total Solar Eclipse Below the Bottom of the World

 2024 March 31

A totally eclipsed Sun is seen in the distance. Around
the eclipse is a dark region dipping down from above. Below
that are clouds and below that is the wing and engine of
an airplane.  
Please see the explanation for more detailed information.

Total Solar Eclipse Below the Bottom of the World
Image Credit & Copyright: Petr Horálek (ESO Photo AmbassadorInst. of Physics in Opava) ; Acknowledgement: Xavier Jubier

Explanation: In late 2021 there was a total solar eclipse visible only at the end of the Earth. To capture the unusual phenomenon, airplanes took flight below the clouded seascape of Southern Ocean. The featured image shows one relatively spectacular capture where the bright spot is the outer corona of the Sun and the eclipsing Moon is seen as the dark spot in the center. A wing and engine of the airplane are visible across the left and bottom of the image, while another airplane observing the eclipse is visible on the far left. The dark area of the sky surrounding the eclipsed Sun is called a shadow cone. It is dark because you are looking down a long corridor of air shadowed by the Moon. A careful inspection of the eclipsed Sun will reveal the planet Mercury just to the right. You won't have to travel to the end of the Earth to see the next total solar eclipse. The total eclipse path will cross North America on 2024 April 8, just over one week from today.

30/03/2024

ASTRONOMY - Medieval Astronomy from Melk Abbey

 024 March 30

See Explanation.  Clicking on the picture will download
 the highest resolution version available.

Medieval Astronomy from Melk Abbey
Image Credit: Paul Beck (Univ. Vienna), Georg Zotti (Vienna Inst. Arch. Science)
Copyright: Library of Melk Abbey, Frag. 229

Explanation: Discovered by accident, this manuscript page provides graphical insight to astronomy in medieval times, before the Renaissance and the influence of Nicolaus CopernicusTycho de BraheJohannes Kepler, and Galileo. The intriguing page is from lecture notes on astronomy compiled by the monk Magister Wolfgang de Styria before the year 1490. The top panels clearly illustrate the necessary geometry for a lunar (left) and solar eclipse in the Earth-centered Ptolemaic system. At lower left is a diagram of the Ptolemaic view of the Solar System with text at the upper right to explain the movement of the planets according to Ptolemy's geocentric model. At the lower right is a chart to calculate the date of Easter Sunday in the Julian calendar. The illustrated manuscript page was found at historic Melk Abbey in Austria.

ASTRONOMY - Christmas Tree Aurora

 2024 December 23 Christmas Tree Aurora Image Credit & Copyright:  Jingyi Zhang Explanation:  It was December and the sky lit up like a ...