9 - SCIENCE - JoanMira
La Science sous toutes ses formes/Science in all its forms
Nombre total de pages vues
02/04/2025
ANIMAUX - "Macaque à queue de lion
ASTRONOMY - Jupiter and Ring in Infrared from Webb
2025 April 2
Image Credit: NASA, ESA, CSA, STScI; Processing & License: Judy Schmidt
Explanation: Why does Jupiter have rings? Jupiter's main ring was discovered in 1979 by NASA's passing Voyager 1 spacecraft, but its origin was then a mystery. Data from NASA's Galileo spacecraft that orbited Jupiter from 1995 to 2003, however, confirmed the hypothesis that this ring was created by meteoroid impacts on small nearby moons. As a small meteoroid strikes tiny Metis, for example, it will bore into the moon, vaporize, and explode dirt and dust off into a Jovian orbit. The featured image of Jupiter in infrared light by the James Webb Space Telescope shows not only Jupiter and its clouds, but this ring as well. Jupiter's Great Red Spot (GRS) -- in comparatively light color on the right, Jupiter's large moon Europa -- in the center of diffraction spikes on the left, and Europa's shadow -- next to the GRS -- are also visible. Several features in the image are not yet well understood, including the seemingly separated cloud layer on Jupiter's right limb.
01/04/2025
ASTRONOMY - A Double Sunrise from a Partial Eclipse
2025 April 1
Video Credit & Copyright: Jason Kurth; Music: House of the Rising Sun (Sebastia McQueen via SoundCloud)
Explanation: Can the Sun appear to rise twice at the same time? This was just the case a few days ago from Les Escoumins, Quebec, Canada as our Solar System's bright central orb rose just as it was being partially eclipsed by the Moon. The featured video shows this unusual double-sunrise in real time and being reflected by the St. Lawrence River. Soon after the initial two spots of light appear over distant clouds, what appears to be bright horns become visible -- which are really just parts of the Sun not being eclipsed. Soon, the entire eclipsed Sun is visible above the horizon. In all, this broken sunrise took less than two minutes during a partial eclipse that lasted many times longer. Although the Moon circles the Earth once a month (moon-th), it does not always eclipse the Sun because its tilted orbit usually takes it above or below.
31/03/2025
ASTRONOMY - Parker: The Solar System from Near the Sun
2025 March 31
Video Credit: NASA, JHUAPL, Naval Research Lab, Parker Solar Probe; h/t: Richard Petarius III;
Music: Russian Easter Festival Overture, Op. 36 by N. Rimsky-Korsakov; Source: Musopen; Performance: Czech National Symphony Orchestra (via Musopen); Music Credit: Wikimedia Commons
Explanation: If you watch long enough, a comet will appear. Before then, you will see our Solar System from inside the orbit of Mercury as recorded by NASA's Parker Solar Probe looping around the Sun. The video captures coronal streamers into the solar wind, a small Coronal Mass Ejection, and planets including, in order of appearance, Mercury, Venus, Saturn, Earth, Mars, and Jupiter. Between the emergence of Earth and Mars, Comet Tempel 1 appears with a distinctive tail. The continuous fleeting streaks are high energy particles from the Sun impacting Parker's sideways looking camera. The featured time-lapse video was taken last year during Encounter 21, Parker's 21st close approach to the Sun. Studying data and images from Parker are delivering a better understanding of the dynamic Sun's effects on Earth's space weather as well as humanity's power grids, spacecraft, and space-faring astronauts.
30/03/2025
ASTRONOMY - A Partial Solar Eclipse over Iceland
2025 March 30
Image Credit & Copyright: Wioleta Gorecka
Explanation: What if the Sun and Moon rose together? That happened yesterday over some northern parts of planet Earth as a partial solar eclipse occurred shortly after sunrise. Regions that experienced the Moon blocking part of the Sun included northeastern parts of North America and northwestern parts of Europe, Asia, and Africa. The featured image was captured yesterday over the Grábrók volcanic crater in Iceland where much of the Sun became momentarily hidden behind the Moon. The image was taken through a cloudy sky but so well planned that the photographer's friend appeared to be pulling the Sun out from behind the Moon. No part of the Earth experienced a total solar eclipse this time. In the distant past, some of humanity was so surprised when an eclipse occurred that ongoing battles suddenly stopped. Today, eclipses are not a surprise and are predicted with an accuracy of seconds.
29/03/2025
ASTRONOMY - Stereo Helene
2025 March 29
Image Credit: Cassini Imaging Team, ISS, JPL, ESA, NASA; Stereo Image by Roberto Beltramini
Explanation: Get out your red/blue glasses and float next to Helene, small, icy moon of Saturn. Appropriately named, Helene is a Trojan moon, so called because it orbits at a Lagrange point. A Lagrange point is a gravitationally stable position near two massive bodies, in this case Saturn and larger moon Dione. In fact, irregularly shaped ( about 36 by 32 by 30 kilometers) Helene orbits at Dione's leading Lagrange point while brotherly ice moon Polydeuces follows at Dione's trailing Lagrange point. The sharp stereo anaglyph was constructed from two Cassini images captured during a close flyby in 2011. It shows part of the Saturn-facing hemisphere of Helene mottled with craters and gully-like features.
28/03/2025
ASTRONOMY - Lunar Dust and Duct Tape
2025 March 28
Image Credit: Apollo 17, NASA
Explanation: Why is the Moon so dusty? On Earth, rocks are weathered by wind and water, creating soil and sand. On the Moon, eons of constant micrometeorite bombardment have blasted away at the rocky surface creating a layer of powdery lunar soil or regolith. For the Apollo astronauts and their equipment, the pervasive, fine, gritty dust was definitely a problem. On the lunar surface in December 1972, Apollo 17 astronauts Harrison Schmitt and Eugene Cernan needed to repair one of their rover's fenders in an effort to keep the rooster tails of dust away from themselves and their gear. This picture reveals the wheel and fender of their dust covered rover along with the ingenious application of spare maps, clamps, and a grey strip of "duct tape".
27/03/2025
Pic de Pucheran : le tambour de la fôret à crête rouge
SANTE/MEDECINE La magnétoencéphalographie (MEG) pour lire le cerveau
ANIMAUX - "Macaque à queue de lion
Ce n'est pourtant pas sa tête auréolée d'une incroyable et soyeuse crinière de poils gris qui lui vaut le surnom de macaque à queue ...
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2021 May 11 Lightning and Orion Beyond Uluru Image Credit & Copyright: Park Liu Explanation: What's happening behind Uluru? A Un...
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2025 January 14 North Star: Polaris and Surrounding Dust Image Credit & Copyright: Davide Coverta Explanation: Why is Polaris called ...