ASTRONOMY - Centaurus A: A Peculiar Island of Stars

2023 May 3

Centaurus A: A Peculiar Island of Stars
Image Credit & Copyright: Marco Lorenzi, Angus Lau & Tommy Tse; Text: Natalia Lewandowska (SUNY Oswego)

Explanation: Galaxies are fascinating. In galaxies, gravity alone holds together massive collections of stars, dust, interstellar gas, stellar remnants and dark matter. Pictured is NGC 5128, better known as Centaurus A. Cen A is the fifth brightest galaxy on the sky and is located at a distance of about 12 million light years from Earth. The warped shape of Cen A is the result of a merger between an elliptical and a spiral galaxy. Its active galactic nucleus harbors a supermassive black hole that is about 55 million times more massive than our Sun. This central black hole ejects a fast jet visible in both radio and X-ray light. Filaments of the jet are visible in red in the upper left. New observations by the Event Horizon Telescope have revealed a brightening of the jet only towards its edges -- but for reasons that are currently unknown and an active topic of research. 

GEMMOLOGIE - La fluorite, le quartz et la rhodochrosite

 

Les minéraux peuvent se rencontrer. Sur cette image, on peut observer un mélange de fluorite (rose clair), de quartz (translucide) et de rhodochrosite (rose éclatant). Ces trois pierres sont très appréciées en joaillerie. 

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

FuturaSciences

ASTRONOMY - Flat Rock Hills on Mars

 2023 May 2

Flat Rock Hills on Mars
Image Credit & Copyright: NASA, JPL-Caltech, MSSS; Processing: Neville Thompson

Explanation: Why are there so many flat rocks on Mars? Some views of plains and hills on Mars show many rocks that are unusually flat when compared to rocks on Earth. One reason for this is a process that is common to both Mars and Earth: erosion. The carbon-dioxide wind on Mars can act like sandpaper when it blows around gritty Martian sand. This sand can create differential erosion, smoothing over some rocks, while wearing down the tops of other long-exposed stones. The featured image capturing several hills covered with flat-topped rocks was taken last month by NASA's Curiosity Rover on Mars. This robotic rover has now been rolling across Mars for ten years and has helped uncover many details of the wet and windy past of Earth's planetary neighbor. After taking this and other images, Curiosity carefully navigated stones and slippery sand to climb up Marker Band Valley.

AERONAUTIQUE - Avions de légende -Le Spirit of St. Louis (l'avion de Charles Lindbergh) et la traversée de l’Atlantique

Le 21 mai 1927, le Spirit of St. Louis piloté par l'aviateur américain Charles Lindbergh se pose sur l'aéroport du Bourget (au nord-est de Paris) après avoir parcouru d'une traite 5.808 kilomètres depuis l'aérodrome Roosevelt de Long Island (New-York, États-Unis).

Cette première traversée transatlantique s'est faite en 33 h et 30 mn dans des conditions épiques. Afin d'alléger au maximum l'appareil et d'embarquer le plus de carburant possible, Charles Lindbergh avait renoncé à emporter un parachute et une radio. Le pilote a effectué l'essentiel du vol aux instruments car la fenêtre frontale de l'appareil était obstruée par un réservoir d'essence.

© Wally Gobetz, CC by-nc 2.0

FuturaSciences

ASTRONOMY - Carina Nebula North

 2023 May 1

Carina Nebula North
Image Credit & Copyright: Carlos Taylor

Explanation: The Great Carina Nebula is home to strange stars and iconic nebulas. Named for its home constellation, the huge star-forming region is larger and brighter than the Great Orion Nebula but less well known because it is so far south -- and because so much of humanity lives so far north. The featured image shows in great detail the northernmost part of the Carina Nebula. On the bottom left is the Gabriela Mistral Nebula consisting of an emission nebula of glowing gas (IC 2599) surrounding the small open cluster of stars (NGC 3324). Above the image center is the larger star cluster NGC 3293, while to its right is the emission nebula Loden 153. The most famous occupant of the Carina Nebula, however, is not shown. Off the image to the lower right is the bright, erratic, and doomed star known as Eta Carinae -- a star once one of the brightest stars in the sky and now predicted to explode in a supernova sometime in the next few million years.

ASTRONOMY - Saturn's Moon Helene in Color

 2023 April 30

Saturn's Moon Helene in Color
Image Credit: NASA, JPL-Caltech, SSI; Processing: Daniel Macháček

Explanation: Although its colors may be subtle, Saturn's moon Helene is an enigma in any light. The moon was imaged in unprecedented detail in 2012 as the robotic Cassini spacecraft orbiting Saturn swooped to within a single Earth diameter of the diminutive moon. Although conventional craters and hills appear, the above image also shows terrain that appears unusually smooth and streaked. Planetary astronomers are inspecting these detailed images of Helene to glean clues about the origin and evolution of the 30-km across floating iceberg. Helene is also unusual because it circles Saturn just ahead of the large moon Dione, making it one of only four known Saturnian moons to occupy a gravitational well known as a stable Lagrange point.

ASTRONOMY - Solar Eclipse from a Ship

 2023 April 29

Solar Eclipse from a Ship
Image Credit: Fred Espenak

Explanation: Along a narrow path that mostly avoided landfall, the shadow of the New Moon raced across planet Earth's southern hemisphere on April 20 to create a rare annular-total or hybrid solar eclipse. From the Indian Ocean off the coast of western Australia, ship-borne eclipse chasers were able to witness 62 seconds of totality though while anchored near the centerline of the total eclipse track. This ship-borne image of the eclipse captures the active Sun's magnificent outer atmosphere or solar corona streaming into space. A composite of 11 exposures ranging from 1/2000 to 1/2 second, it records an extended range of brightness to follow details of the corona not quite visible to the eye during the total eclipse phase. Of course eclipses tend to come in pairs. On May 5, the next Full Moon will just miss the dark inner part of Earth's shadow in a penumbral lunar eclipse.

ASTRONONOMY - Runaway Star Alpha Camelopardalis

 2023 April 28

Runaway Star Alpha Camelopardalis
Image Credit: André Vilhena

Explanation: Like a ship plowing through cosmic seas, runaway star Alpha Camelopardalis has produced this graceful arcing bow wave or bow shock. The massive supergiant star moves at over 60 kilometers per second through space, compressing the interstellar material in its path. At the center of this nearly 6 degree wide view, Alpha Cam is about 25-30 times as massive as the Sun, 5 times hotter (30,000 kelvins), and over 500,000 times brighter. About 4,000 light-years away in the long-necked constellation Camelopardalis, the star also produces a strong stellar wind. Alpha Cam's bow shock stands off about 10 light-years from the star itself. What set this star in motion? Astronomers have long thought that Alpha Cam was flung out of a nearby cluster of young hot stars due to gravitational interactions with other cluster members or perhaps by the supernova explosion of a massive companion star.

ASTRONOMY -The Tarantula Nebula from SuperBIT

 2023 April 27

The Tarantula Nebula from SuperBIT
Image Credit: SuperBIT, NASA

Explanation: The Tarantula Nebula, also known as 30 Doradus, is more than a thousand light-years in diameter, a giant star forming region within nearby satellite galaxy the Large Magellanic Cloud. About 160 thousand light-years away, it's the largest, most violent star forming region known in the whole Local Group of galaxies. The cosmic arachnid is near the center of this spectacular image taken during the flight of SuperBIT (Super Pressure Balloon Imaging Telescope), NASA's balloon-borne 0.5 meter telescope now floating near the edge of space. Within the well-studied Tarantula (NGC 2070), intense radiation, stellar winds and supernova shocks from the central young cluster of massive stars, cataloged as R136, energize the nebular glow and shape the spidery filaments. Around the Tarantula are other star forming regions with young star clusters, filaments, and blown-out bubble-shaped clouds. SuperBIT's wide field of view spans over 2 degrees or 4 full moons in the southern constellation Dorado.

ART FRACTAL - Détail de l'ensemble de Mandelbrot

Cette fractale représente un détail de l'ensemble de Mandelbrot. Deux figures en forme de S quasi identiques, l'une dans les tons bleu-jaune et l'autre dans les nuances rose-bleu, semblent se tenir par la main. Comme pour toute fractale, si on regarde de près un détail, on obtient la même structure que l'ensemble. 

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