ASTRONOMY - Planets of the Solar System: Tilts and Spins

 2025 September 14

Planets of the Solar System: Tilts and Spins
Video Credit: NASA, Animation: James O'Donoghue (U. Reading)

Explanation: How does your favorite planet spin? Does it spin rapidly around a nearly vertical axis, or horizontally, or backwards? The featured video animates NASA images of all eight planets in our Solar System to show them spinning side-by-side for an easy comparison. In the time-lapse video, a day on Earth -- one Earth rotation -- takes just a few seconds. Jupiter rotates the fastest, while Venus spins not only the slowest (can you see it?), but backwards. The inner rocky planets across the top underwent dramatic spin-altering collisions during the early days of the Solar System. Why planets spin and tilt as they do remains a topic of research with much insight gained from modern computer modeling and the recent discovery and analysis of hundreds of exoplanets: planets orbiting other stars.

ASTRONOMY - Star Trails over One-Mile Radio Telescope

 2025 September 13

Star Trails over One-Mile Radio Telescope
Image Credit & Copyright: Joao Yordanov Serralheiro

Explanation: The steerable 60 foot diameter dish antenna of the One-Mile Telescope at Mullard Radio Astronomy Observatory, Cambridge, UK, is pointing skyward in this evocative night-skyscape. To capture the dramatic scene, consecutive 30 second exposures were recorded over a period of 90 minutes. Combined, the exposures reveal a background of gracefully arcing star trails that reflect planet Earth's daily rotation on its axis. The North Celestial Pole, the extension of Earth's axis of rotation into space, points near Polaris, the North Star. That's the bright star that creates the short trail near the center of the concentric arcs. But the historic One-Mile Telescope array also relied on planet Earth's rotation to operate. Exploring the universe at radio wavelengths, it was the first radio telescope to use Earth-rotation aperture synthesis. That technique uses the rotation of the Earth to change the relative orientation of the telescope array and celestial radio sources to create radio maps of the sky at a resolution better than that of the human eye.

ASTRONOMY - Lunar Eclipse in Two Hemispheres

 2025 September 12

Lunar Eclipse in Two Hemispheres
Image Credit & Copyright: North - Zhouyue Zhu, South - Lucy Yunxi Hu

Explanation: September's total lunar eclipse is tracked across night skies from both the northern and southern hemispheres of planet Earth in these two dramatic timelapse series. In the northern hemisphere sequence (top panel) the Moon’s trail arcs from the upper left to the lower right. It passes below bright planet Saturn, seen under mostly clear skies from the international campus of Zhejiang University in China at about 30 degrees north latitude. In contrast, the southern hemisphere view from Lake Griffin, Canberra, Australia at 35 degrees south latitude, records the Moon’s trail from the upper right to the lower left. Multiple lightning flashes from thunderstorms near the horizon appear reflected in the lake. Both sequences were photographed with 16mm wide-angle lenses and both cover the entire eclipse, with the darkened red Moon totally immersed in Earth's umbral shadow near center. But the different orientations of the Moon’s path across the sky reveal the perspective shifts caused by the views from northern vs. southern latitudes.

SANTé/MEDECINE - Remèdes de Grand-mère - Dépuratif du foie

À jeun, dès votre réveil, avalez 1 cuillère à soupe d'huile d'olive "première pression à froid". Pour faciliter l'ingestion de l'huile d'olive, ajoutez quelques gouttes de jus de citron pressé dans la cuillère. 

Sachez que les mauvais aliments pour le foie sont ceux qui ont une haute teneur en graisse, les sauces grasses, les fritures, les pâtisseries et l'alcool. 

Les bons aliments pour le foie sont les artichauts et les pissenlits qui ont le pouvoir de désintoxiquer un foie irrité. Et si vous cherchez les "légumes-miracles" pour le foie, tournez-vous vers les carottes, le cresson, toutes les salades (même cuites), les tomates et les olives. Certains fruits ont aussi des bienfaits sur le foie comme les agrumes, le raisin sec et les pommes.

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ASTRONOMY - The Umbra of Earth

2025 September 11

The Umbra of Earth
Image Credit & Copyright: Wang Letian (Eyes at Night)

Explanation: The dark, inner shadow of planet Earth is called the umbra. Shaped like a cone extending into space, it has a circular cross section most easily seen during a lunar eclipse. And on the night of September 7/8 the Full Moon passed near the center of Earth's umbral cone, entertaining eclipse watchers around much of our fair planet, including parts of Antarctica, Australia, Asia, Europe, and Africa. Recorded from Zhangjiakou City, China, this timelapse composite image uses successive pictures from the total lunar eclipse, progressing left to right, to reveal the curved cross-section of the umbral shadow sliding across the Moon. Sunlight scattered by the atmosphere into Earth's umbra causes the lunar surface to appear reddened during totality. But close to the umbra's edge, the limb of the eclipsed Moon shows a distinct blue hue. The blue eclipsed moonlight originates as rays of sunlight pass through layers high in the upper stratosphere, colored by ozone that scatters red light and transmits blue. In the total phase of this leisurely lunar eclipse, the Moon was completely within the Earth's umbra for about 83 minutes. 

ASTRONOMY - IRAS 04302: Butterfly Disk Planet Formation

 2025 September 8

IRAS 04302: Butterfly Disk Planet Formation
Image Credit: NASA, ESA, CSA, Webb; Processing: M. Villenave et al.

Explanation: This butterfly can hatch planets. The nebula fanning out from the star IRAS 04302+2247 may look like the wings of a butterfly, while the vertical brown stripe down the center may look like the butterfly's body -- but together they indicate an active planet-forming system. The featured picture was captured recently in infrared light by the Webb Space Telescope. Pictured, the vertical disk is thick with the gas and dust from which planets form. The disk shades visible and (most) infrared light from the central star, allowing a good view of the surrounding dust that reflects out light. In the next few million years, the dust disk will likely fragment into rings through the gravity of newly hatched planets. And a billion years from now, the remaining gas and dust will likely dissipate, leaving mainly the planets -- like in our Solar System.

ASTRONOMY - Up from the Earth: Gigantic Jet Lightning

2025 September 9

Up from the Earth: Gigantic Jet Lightning
Image Credit: NASA, Expedition 73, Nicole Ayers

Explanation: What's that rising up from the Earth? When circling the Earth on the International Space Station early in July, astronaut Nicole Ayers saw an unusual type of lightning rising up from the Earth: a gigantic jet. The powerful jet appears near the center of the featured image in red, white, and blue. Giant jet lightning has only been known about for the past 25 years. The atmospheric jets are associated with thunderstorms and extend upwards towards Earth's ionosphere. The lower part of the frame shows the Earth at night, with Earth's thin atmosphere tinted green from airglow. City lights are visible, sometimes resolved, but usually creating diffuse white glows in intervening clouds. The top of the frame reveals distant stars in the dark night sky. The nature of gigantic jets and their possible association with other types of Transient Luminous Events (TLEs) such as blue jets and red sprites remain active topics of research. 

ASTRONOMIE - Lune de sang

Les passionnés d’astronomie ont observé ce dimanche comme ici au-dessus des pyramides de Gizeh, en Égypte, une Lune de sang, à l’occasion d’une éclipse lunaire totale. Ce phénomène, qui teinte de rouge le satellite de la Terre, se produit quand le soleil, la Terre et la Lune sont parfaitement alignés dans cet ordre et que la Lune est dans sa phase pleine. 

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ASTRONOMY - 2025 September 7

 2025 September 7

All the Water on Planet Earth
Illustration Credit: Jack Cook, Adam Nieman, Woods Hole Oceanographic Institution; Data source: Igor Shiklomanov

Explanation: How much of planet Earth is made of water? Very little, actually. Although oceans of water cover about 70 percent of Earth's surface, these oceans are shallow compared to the Earth's radius. The featured illustration shows what would happen if all of the water on or near the surface of the Earth were bunched up into a ball. The radius of this ball would be only about 700 kilometers, less than half the radius of the Earth's Moon, but slightly larger than Saturn's moon Rhea which, like many moons in our outer Solar System, is mostly water ice. The next smallest ball depicts all of Earth's liquid fresh water, while the tiniest ball shows the volume of all of Earth's fresh-water lakes and rivers. How any of this water came to be on the Earth and whether any significant amount is trapped far beneath Earth's surface remain topics of research.

ASTRONOMIE - Un phénomène astronomique exceptionnel illuminera la nuit de rouge ce soir

Dans la nuit du 7 au 8 septembre, le ciel se transformera sous nos yeux lors d'un événement astronomique rare, avec un spectacle magnifique et accessible à tous, visible par une grande partie de l'humanité.

Dans quelques heures, lever les yeux suffira pour assister à un spectacle qui ne ressemble à rien de ce que l'on voit d'ordinaire. La Lune, familière et pâle compagne des nuits, prendra des allures surnaturelles. Son disque s'assombrira peu à peu, puis se colorera d'un rouge profond, comme si le ciel lui-même se teignait de braises. Ce phénomène, qui attire autant les passionnés d'astronomie que les curieux, s'annonce comme l'un des plus impressionnants de la décennie.

L'événement en question n'est autre qu'une éclipse lunaire totale, un rendez-vous rare où la Terre se glisse entre le Soleil et son satellite. Cette fois-ci, la durée frôle l'exception : 3 heures et 30 minutes pour suivre chaque étape de la métamorphose. Contrairement aux éclipses solaires, qui exigent lunettes spécialisées et prudence, celle-ci peut se contempler à l'œil nu, sans danger. Un luxe pour les observateurs qui n'auront qu'à trouver un ciel dégagé.

La portée de cette éclipse dépasse largement les frontières. Les astronomes estiment que près de 7 milliards d'humains pourront l'admirer, soit environ 60 % de la population mondiale. L'Asie, une partie de l'Afrique et l'ouest de l'Australie auront droit au spectacle complet. En Europe, en Amérique du Sud et dans d'autres régions du globe, il sera au moins partiellement visible. Autant dire qu'il s'agit d'un moment partagé à une échelle rarement atteinte.

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