Science & Technology - Astronomy picture of the day : Pluto at Night

2019 October 20
Pluto at Night 
Image Credit: NASA, Johns Hopkins Univ./APL, Southwest Research Institute 

Explanation: The night side of Pluto spans this shadowy scene, a stunning spacebased view with the Sun 4.9 billion kilometers (almost 4.5 light-hours) behind the dim and distant world. It was captured by far flung New Horizons in July of 2015. The spacecraft was at a range of some 21,000 kilometers from Pluto, about 19 minutes after its closest approach. A denizen of the Kuiper Belt in dramatic silhouette, the image also reveals Pluto's tenuous, surprisinglycomplex layers of hazy atmosphere. The crescent twilight landscape near the top of the frame includes southern areas of nitrogen ice plains now formally known as Sputnik Planitia and rugged mountains of water-ice in the Norgay Montes.

Science & Technology - Astronomy picture of the day : All Female Spacewalk Repairs Space Station

2019 October 19
All Female Spacewalk Repairs Space Station 
Image Credit: NASA TV, Expedition 61

Explanation: The failed unit was beyond the reach of the robotic Canadarm2. Therefore, this repair of the International Space Station would require humans. The humans on duty were NASA's Jessica Meir and Christina Koch. This was the fourth spacewalk for Meir, the first for Koch, and the first all-female spacewalk in human history. The first woman to walk in space was Svetlana Savitskaya in 1984. Koch (red stripe) and Weir are pictured hard at work on the P6 Truss, with solar panels and the darkness of space in the background. Working over seven hours, the newly installed Battery Charge / Discharge Unit (BCDU) was successfully replaced and, when powered up, operated normally.

Science & Technology - Astronomy picture of the day - BHB2007: A Baby Binary Star in Formation

2019 October 16
BHB2007: A Baby Binary Star in Formation 
Image Credit: ALMA (ESO/NAOJ/NRAO), F. O. Alves et al.

Explanation: How do binary stars form? To help find out, ESO's Atacama Large Millimeter Array (ALMA) recently captured one of the highest resolution images yet taken of a binary star system in formation. Most stars are not alone -- they typically form as part of a multiple star systems where star each orbits a common center of gravity. The two bright spots in the featured image are small disks that surround the forming proto-stars in [BHB2007] 11, while the surrounding pretzel-shaped filaments are gas and dust that have been gravitationally pulled from a larger disk. The circumstellar filaments span roughly the radius of the orbit of Neptune. The BHB2007 system is a small part of the Pipe Nebula (also known as Barnard 59), a photogenic network of dust and gas that protrudes from Milky Way's spiral disk in the constellation of Ophiuchus. The binary star formation process should be complete within a few million years.

Fotografia - "Pace e amore"

"Pace e amore"

Science & Technology - Astronomy picture of the day : MyCn 18: The Engraved Hourglass Planetary Nebula

2019 September 29
MyCn 18: The Engraved Hourglass Planetary Nebula Image Credit: NASA, ESA, Hubble; Processing & License: Judy Schmidt

Explanation: Do you see the hourglass shape -- or does it see you? If you can picture it, the rings of MyCn 18 trace the outline of an hourglass -- although one with an unusual eye in its center. Either way, the sands of time are running out for the central star of this hourglass-shaped planetary nebula. With its nuclear fuel exhausted, this brief, spectacular, closing phase of a Sun-like star's life occurs as its outer layers are ejected - its core becoming a cooling, fadingwhite dwarf. In 1995, astronomers used the Hubble Space Telescope (HST) to make a series of images of planetary nebulae, including the one featured here. Pictured, delicate rings of colorful glowing gas (nitrogen-red, hydrogen-green, and oxygen-blue) outline the tenuous walls of the hourglass. The unprecedented sharpness of the Hubble images has revealed surprising details of the nebula ejection process that are helping to resolve the outstanding mysteries of the complex shapes and symmetries of planetary nebulas like MyCn 18.

Science & Technology - Astronomy picture of the day : An Analemma of the Sun

2019 September 28
An Analemma of the Sun 
Image Credit & Copyright: Gyorgy Soponyai

Explanation: This week the equinox found the Sun near the middle, but not at the crossing point, of an analemma in its annual trek through planet Earth's skies. In this scenic view, that graceful, figure-8-shaped curve was intentionally posed above the iconic Danube River and the capital city of Hungary. Looking south from Budapest's Margaret Bridge it combines digital frames taken at exactly the same time of day (11:44 CET) on dates between 2018 September 24 and 2019 September 15. That puts the metropolitan Pest on the left, regal Buda on the right, and the positions of the Sun on the solstice dates at the top and bottom of the analemma curve. December's near solstice Sun is just hidden behind a dramatic cloud bank.

Science & Technology - Astronomy picture of the day : Da Vinci Rise

2019 September 26
Da Vinci Rise 
Image Credit & Copyright: Likai Lin

Explanation: An old Moon rose this morning, its waning sunlit crescent shining just above the eastern horizon before sunrise. But earthshine, light reflected from a bright planet Earth, lit the shadowed portion of the lunar disk and revealed most of a familiar lunar near side to early morning risers. In fact, a description of earthshine in terms of sunlight reflected by Earth's oceans illuminating the Moon's dark surface was written over 500 years ago by Leonardo da Vinci. One lunation ago this old Moon also rose above the eastern horizon. Its sunlit crescent and da Vinci glow were captured in stacked exposures from the Badain Jilin Desert of Inner Mongolia, China on August 29, 2019. This year marks the 500th anniversary of Leondardo da Vinci's death.

Science & Technology - Astronomy picture of the day : The Pelican Nebula in Gas, Dust, and Stars

2019 September 25
The Pelican Nebula in Gas, Dust, and Stars 
Image Credit & Copyright: Yannick Akar

Explanation: The Pelican Nebula is slowly being transformed. IC 5070, the official designation, is divided from the larger North America Nebula by a molecular cloud filled with dark dust. The Pelican, however, receives much study because it is a particularly active mix of star formation and evolving gas clouds. The featured picture was produced in three specific colors -- light emitted by sulfur, hydrogen, and oxygen -- that can help us to better understand these interactions. The light from young energetic stars is slowly transforming the cold gas to hot gas, with the advancing boundary between the two, known as an ionization front, visible in bright orange on the right. Particularly dense tentaclesof cold gas remain. Millions of years from now this nebula might no longer be known as the Pelican, as the balance and placement of stars and gas will surely leave something that appears completely different.

Science & Technologie - Aeronautique - Avions du futur ? :Hoax : le Boeing 797, un vrai-faux projet d'avion géant

Le concept de Boeing X48 BWB (Blended Wing Body, fuselage porteur) a inspiré des plaisantins qui ont utilisé cette image publiée dans la revue Popular Science pour annoncer, au moment de la présentation de l'Airbus A380, ce « Boeing 797 » qui pourrait embarquer un millier de passagers. Il s'agissait d'un canular (ou hoax) mais la réalité pourrait un jour rattraper la fiction... 

© DR

Science & Technologie - Santé : Comment lire son analyse de sang - Taux du cholestérol sanguin - 1 de 10

Le sang est une véritable mine d'informations sur l'état de santé. L'analyse de sang permet tout à la fois de surveiller une maladie chronique, de vérifier que tout va bien avant une opération ou de rechercher le dysfonctionnement d'un organe.

Seulement, entre l'hémogramme, la vitesse de sédimentation et les autres paramètres, il y a de quoi s'y perdre ! D'autant que les normes peuvent varier entre les laboratoires. "Ce sont des moyennes, explique le Dr Isabelle Bernard, médecin-biologiste. Elles peuvent être légèrement différentes d'un laboratoire à l'autre : tout dépend des techniques utilisées."stérol sanguin

C'est la quantité de graisses (lipoprotéines) circulant dans le sang. La mesure du cholestérol total est suffisante pour un contrôle de base. Pour une analyse plus fine, le biologiste dose les substances qui transportent le cholestérol dans le sang : les HDL (high density lipoproteine) correspondent au "bon" cholestérol, les LDL (low density lipoproteine) au "mauvais". Ce sont les LDL qui se déposent sur les parois des artères et qui sont facteurs de troubles. Le rapport cholestérol total/HDL permet d'évaluer le risque cardio-vasculaire.

Le taux est élevé

Le patient présente un risque de maladie cardio-vasculaire.

Le taux est bas

Une valeur trop faible n'est pas normale non plus. C'est le signe d'un trouble hormonal ou d'une malnutrition.

Valeur normale du cholestérol total : inférieure à 2 g/l.

Santé Magazine - France