LA TERRE VUE DU CIEL - Le parc national de Canyonlands dans l’Utah

Le parc national de Canyonlands est situé dans l'Utah non loin de Moab (États-Unis). Cette image prise par Landsat 7 montre les trois principales parties du parc : Island in the Sky, the Needles et The Maze. Canyonlands offre un paysage minéral aride, façonné par l'érosion provoquée par le fleuve Colorado et la Green River dont les affluents ont creusé et sculpté la roche au cours de milliers d'années, laissant derrière eux des formes extraordinaires et un témoignage géologique unique.

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ASTRONOMY - Hickson 44 in Leo

 2025 April 4

Hickson 44 in Leo
Image Credit & Copyright: Jiang Wu

Explanation: Scanning the skies for galaxies, Canadian astronomer Paul Hickson and colleagues identified some 100 compact groups of galaxies, now appropriately called Hickson Compact Groups. The four prominent galaxies seen in this intriguing telescopic skyscape are one such group, Hickson 44. The galaxy group is about 100 million light-years distant, far beyond the spiky foreground Milky Way stars, toward the constellation Leo. The two spiral galaxies in the center of the image are edge-on NGC 3190 with its distinctive, warped dust lanes, and S-shaped NGC 3187. Along with the bright elliptical, NGC 3193 (above and left) they are also known as Arp 316. The spiral toward the lower right corner is NGC 3185, the 4th member of the Hickson group. Like other galaxies in Hickson groups, these show signs of distortion and enhanced star formation, evidence of a gravitational tug of war that will eventually result in galaxy mergers on a cosmic timescale. The merger process is now understood to be a normal part of the evolution of galaxies, including our own Milky Way. For scale, NGC 3190 is about 75,000 light-years across at the estimated distance of Hickson 44.

ASTRONOMY - The Da Vinci Glow

 2025 April 3

The Da Vinci Glow
Image Credit & Copyright: Giorgia Hofer

Explanation: A 26 hour old Moon poses behind the craggy outline of the Italian Dolomites in this twilight mountain and skyscape. The one second long exposure was captured near moonset on March 30. And while only a a sliver of its sunlit surface is visible, most of the Moon's disk can be seen by earthshine as light reflected from a bright planet Earth illuminates the lunar nearside. Also known as the Moon's ashen glow, 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. Of course earthshine is just the most familiar example of planetshine, the faint illumination of the dark portion of a moon by light reflected from its planet.

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 de lion mais bien sa queue robuste et terminée par une frange touffue. Sa longue fourrure est atypique et unique chez le macaque. Même s'il est le plus petit représentant de son espèce, ce macaque, aussi appelé ouandérou, aux allures de grand sage barbu, peut vivre 20 ans et plus. Son habitat est celui des forêts tropicales du sud-ouest de l'Inde où il passe son temps dans la canopée des arbres, ce qui le rend difficile à approcher. D'ailleurs, il est le seul macaque à se tenir éloigné des êtres humains. Considéré comme l'espèce ancestrale des macaques d'Asie, le macaque à queue de lion (Macaca silenus) est menacé par la déforestation et la diminution de son aire de répartition au profit de plantations diverses. S'il n'est plus inscrit sur la liste des 25 espèces de primates les plus menacées dans le monde, il ne se compterait plus que 3.500 individus de cette espèce endémique.

Macaque à queue de lion, près de Valparai dans les collines d'Anamalai, en Inde. 

© T. R. Shankar Raman, Wikimedia Commons, CC by-sa 4.0

ASTRONOMY - Jupiter and Ring in Infrared from Webb

 2025 April 2

Jupiter and Ring in Infrared from Webb
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.

ASTRONOMY - A Double Sunrise from a Partial Eclipse

 2025 April 1

A Double Sunrise from a Partial Eclipse
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.

ASTRONOMY - Parker: The Solar System from Near the Sun

 2025 March 31

Parker: The Solar System from Near the Sun
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.

ASTRONOMY - A Partial Solar Eclipse over Iceland

 2025 March 30

A Partial Solar Eclipse over Iceland
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.

LA TERRE VUE DU CIEL - Dunes dans le désert de Namibie

Hautes dunes dans le désert de Namibie.

© Nasa

ASTRONOMY - Stereo Helene

 2025 March 29

Stereo Helene
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.