ASTRONOMY - Moons Across Jupiter

 2023 June 13

Moons Across Jupiter
Image Credit: NASA; ESA, JPL, Cassini Imaging Team, SSI; Processing: Kevin M. Gill

Explanation: Jupiter's moons circle Jupiter. The featured video depicts Europa and Io, two of Jupiter's largest moons, crossing in front of the grand planet's Great Red Spot, the largest known storm system in our Solar System. The video was composed from images taken by the robotic Cassini spacecraft as it passed Jupiter in 2000, on its way to Saturn. The two moons visible are volcanic Io, in the distance, and icy Europa. In the time-lapse video, Europa appears to overtake Io, which is odd because Io is closer to Jupiter and moves faster. The explanation is that the motion of the fast Cassini spacecraft changes the camera location significantly during imaging. Jupiter is currently being visited by NASA's robotic Juno spacecraft, while ESA's Jupiter Icy Moons Explorer (JUICE), launched in April, is enroute.

DELICIEUSES HERBES AROMATIQUES - Le romarin

Le romarin officinal, reconnaissable à ses fleurs bleutées, est un arbrisseau de la famille des Lamiacées. Il pousse à l'état sauvage sur le pourtour méditerranéen, dans les garrigues arides et rocailleuses.

La plante s'utilise de préférence fraîche mais les fleurs séchées parfument agréablement un plat ou un dessert. Il sert également à aromatiser les grillades ou à rehausser les ragoûts, les civets, les soupes ou les sauces.

Le romarin est mellifère et contient plusieurs agents actifs antimycosiques, antibactériens et antioxydants. Il est également utilisé en parfumerie depuis le XIVe siècle.  

© Cyclonebill, CC by-sa 2.0 et Tony Hisgett, CC by 2.0

ASTROPHOTOGRAPHIE - La lune dans les ailes

"La Lune dans les ailes" 

Pierre Derycke

ASTRONOMY - Simulation: A Disk Galaxy Forms

 2023 May 31

Simulation: A Disk Galaxy Forms
Video Credit: TNG Collaboration, MPCDF, FAS Harvard U.; Music: World's Sunrise (YouTube: Jimena Contreras)

Explanation: How did we get here? We know that we live on a planet orbiting a star orbiting a galaxy, but how did all of this form? Since our universe moves too slowly to watch, faster-moving computer simulations are created to help find out. Specifically, this featured video from the IllustrisTNG collaboration tracks gas from the early universe (redshift 12) until today (redshift 0). As the simulation begins, ambient gas falls into and accumulates in a region of relatively high gravity. After a few billion years, a well-defined center materializes from a strange and fascinating cosmic dance. Gas blobs -- some representing small satellite galaxies -- continue to fall into and become absorbed by the rotating galaxy as the present epoch is reached and the video ends. For the Milky Way Galaxy, however, big mergers may not be over -- recent evidence indicates that our large spiral disk Galaxy will collide and coalesce with the slightly larger Andromeda spiral disk galaxy in the next few billion years.

ASTRONOMY - Elephant's Trunk and Caravan

 2023 June 8

Elephant's Trunk and Caravan
Image Credit & Copyright: Steve Cannistra (StarryWonders)

Explanation: Like an illustration in a galactic Just So Story, the Elephant's Trunk Nebula winds through the emission region and young star cluster complex IC 1396, in the high and far off constellation of Cepheus. Seen on the left the cosmic elephant's trunk, also known as vdB 142, is over 20 light-years long. This detailed telescopic view features the bright swept-back ridges and pockets of cool interstellar dust and gas that abound in the region. But the dark, tendril-shaped clouds contain the raw material for star formation and hide protostars within. Nearly 3,000 light-years distant, the relatively faint IC 1396 complex covers a large region on the sky, spanning over 5 degrees. This rendition spans a 1 degree wide field of view though, about the angular size of 2 full moons. Of course the dark shapes below and to the right of the outstretched Elephant's Trunk, are known to some as The Caravan.

ASTRONOMY - M94: A Double Ring Galaxy

 2023 June 7

M94: A Double Ring Galaxy
Image Credit & Copyright: Brian Brennan

Explanation: Most galaxies don't have any rings of stars and gas -- why does M94 have two? First, spiral galaxy M94 has an inner ring of newly formed stars surrounding its nucleus, giving it not only an unusual appearance but also a strong interior glow. A leading origin hypothesis holds that an elongated knot of stars known as a bar rotates in M94 and has generated a burst of star formation in this inner ring. Observations have also revealed another ring, an outer ring, one that is more faint, different in color, not closed, and relatively complex. What caused this outer ring is currently unknown. M94, pictured here, spans about 45,000 light years in total, lies about 15 million light years away, and can be seen with a small telescope toward the constellation of the Hunting Dogs (Canes Venatici).

AERONAUTIQUE - Avions de légende - Le Canadair CL 415 - un bombardier d'eau à la capacité impressionnante

Le Canadair CL-415 est un avion bombardier d’eau fabriqué par la firme canadienne Bombardier Aéronautique. Spécialisé dans la lutte contre les incendies, il est utilisé par de nombreux pays, dont la France où il est affublé du surnom de « Pélican ». Cet avion réputé pour sa fiabilité possède deux réservoirs qui peuvent emmagasiner un peu plus de 6.000 litres d’eau.

© Claudio, CC by-nc 2.0

GEMMOLOGIE - La magnifique topaze

Espèce minérale de formule Al2SiO4(F,OH)2, la topaze peut contenir des traces de fer, de chrome, de magnésium et de titane. Lorsqu'on expose longtemps cette pierre fine à la lumière solaire, elle peut changer de couleur. Couleurs : incolore à blanc, bleu, verdâtre, brun jaune, orange, rose, rougeâtre, violet, brun.

© Rob Lavinsky, Wikimedia Commons, CC by-sa 3.0

ASTRONOMY - Star Eats Planet

 2023 June 6

Star Eats Planet
Illustrative Video Credit: K. Miller & R. Hurt (Caltech, IPAC)

Explanation: It’s the end of a world as we know it. Specifically, the Sun-like star ZTF SLRN-2020 was seen eating one of its own planets. Although many a planet eventually dies by spiraling into their central star, the 2020 event, involving a Jupiter-like planet, was the first time it was seen directly. The star ZTF SLRN-2020 lies about 12,000 light years from the Sun toward the constellation of the Eagle (Aquila). In the featured animated illustration of the incident, the gas planet's atmosphere is first pictured being stripped away as it skims along the outskirts of the attracting star. Some of the planet's gas is absorbed into the star's atmosphere, while other gas is expelled into space. By the video's end, the planet is completely engulfed and falls into the star's center, causing the star's outer atmosphere to briefly expand, heat up, and brighten. One day, about eight billion years from now, planet Earth may spiral into our Sun.

ASTRONOMY - In the Center of the Trifid Nebula

 2023 June 5

In the Center of the Trifid Nebula
Image Credit & Copyright: Martin Pugh

Explanation: What's happening at the center of the Trifid Nebula? Three prominent dust lanes that give the Trifid its name all come together. Mountains of opaque dust appear near the bottom, while other dark filaments of dust are visible threaded throughout the nebula. A single massive star visible near the center causes much of the Trifid's glow. The Trifid, cataloged as M20, is only about 300,000 years old, making it among the youngest emission nebulas known. The star forming nebula lies about 9,000 light years away toward the constellation of the Archer (Sagittarius). The region pictured here spans about 20 light years.