ASTRONOMY - Northern Lights over Southern Europe

 2023 April 25

Northern Lights over Southern Europe
Image Credit & Copyright: Lorenzo Cordero

Explanation: Did you see an aurora over the past two nights? Many people who don't live in Earth's far north did. Reports of aurora came in not only from northern locales in the USA as Alaska, but as far south as Texas and Arizona. A huge auroral oval extended over Europe and Asia, too. Pictured, an impressively red aurora was captured last night near the town of Cáceres in central Spain. Auroras were also reported in parts of southern Spain. The auroras resulted from a strong Coronal Mass Event (CME) that occurred on the Sun a few days ago. Particles from the CME crossed the inner Solar System before colliding with the Earth's magnetosphere. From there, electrons and protons spiraled down the Earth's northern magnetic field lines and collided with oxygen and nitrogen in Earth's atmosphere, causing picturesque auroral glows. Our unusually active Sun may provide future opportunities to see the northern lights in southern skies.

ASTRONOMY - NGC 1333: Stellar Nursery in Perseus

 2023 April 22

NGC 1333: Stellar Nursery in Perseus
Image Credit: Science - NASA, ESA, STScI, Processing - Varun Bajaj (STScI),
Joseph DePasquale (STScI), Jennifer Mack (STScI)

Explanation: In visible light NGC 1333 is seen as a reflection nebula, dominated by bluish hues characteristic of starlight reflected by interstellar dust. A mere 1,000 light-years distant toward the heroic constellation Perseus, it lies at the edge of a large, star-forming molecular cloud. This Hubble Space Telescope close-up frames a region just over 1 light-year wide at the estimated distance of NGC 1333. It shows details of the dusty region along with telltale hints of contrasty red emission from Herbig-Haro objects, jets and shocked glowing gas emanating from recently formed stars. In fact, NGC 1333 contains hundreds of stars less than a million years old, most still hidden from optical telescopes by the pervasive stardust. The chaotic environment may be similar to one in which our own Sun formed over 4.5 billion years ago. Hubble's stunning image of the stellar nursery was released to celebrate the 33rd anniversary of the space telescope's launch.

ASTRONOMY - A Waterspout in Florida

 2023 April 23

A Waterspout in Florida
Image Credit & Copyright: Joey Mole

Explanation: What's happening over the water? Pictured here is one of the better images yet recorded of a waterspout, a type of tornado that occurs over water. Waterspouts are spinning columns of rising moist air that typically form over warm water. Waterspouts can be as dangerous as tornadoes and can feature wind speeds over 200 kilometers per hour. Some waterspouts form away from thunderstorms and even during relatively fair weather. Waterspouts may be relatively transparent and initially visible only by an unusual pattern they create on the water. The featured image was taken in 2013 July near Tampa Bay, Florida. The Atlantic Ocean off the coast of Florida is arguably the most active area in the world for waterspouts, with hundreds forming each year.

AERONAUTIQUE - Avions de légende - Le Supermarine Spitfire et son moteur Rolls-Royce

Avec le Messerschmitt Bf 109, le Supermarine Spitfire est l'autre avion de chasse légendaire à s'être illustré durant la seconde guerre mondiale. C'est notamment grâce à lui que la Royal Air Force britannique a pu remporter la célèbre bataille d'Angleterre.

Ce monoplan à ailes elliptiques se caractérise par son profil très aérodynamique qui lui permettait d'atteindre les 650 km/h grâce à son moteur Rolls-Royce. Le Supermarine Spitfire fut produit à plus de 20.300 exemplaires, avec des déclinaisonsutilisées par plusieurs pays, notamment l'Égypte, la France, Israël ou encore la Turquie.

© Jez, CC by-nc 2.0

FuturaSciences

ASTRONOMY - Auroral Storm over Lapland

 2023 April 19

Auroral Storm over Lapland
Image Credit & Copyright: Juan Carlos Casado (Starry Earth, TWAN)

Explanation: On some nights the sky is the best show in town. On this night, auroras ruled the sky, and the geomagnetic storm that created this colorful sky show originated from an increasingly active Sun. Surprisingly, since the approaching solar CME the day before had missed the Earth, it was not expected that this storm would create auroras. In the foreground, two happily surprised aurora hunters contemplate the amazing and rapidly changing sky. Regardless of forecasts, though, auroras were reported in the night skies of Earth not only in the far north, but as far south as New Mexico, USA. As captured in a wide-angle image above Saariselkä in northern Finnish Lapland, a bright aurora was visible with an unusually high degree of detail, range of colors, and breadth across the sky. The vivid yellow, green, red and purple auroral colors are caused by oxygen and nitrogen atoms high in Earth's atmosphere reacting to incoming electrons.

ART FRACTAL - Intrigante fractale asymétrique

Cette image fractale est complètement asymétrique. Du côté gauche, le fond est sombre et monochromatique alors que du côté droit, plusieurs bandes de couleursvives s'entrecoupent. 

© Futura 

ASTRONOMY - M2-9: Wings of a Butterfly Nebula

 2023 April 16

M2-9: Wings of a Butterfly Nebula
Image Credit: Hubble Legacy Archive, NASA, ESA; Processing: Judy Schmidt

Explanation: Are stars better appreciated for their art after they die? Actually, stars usually create their most artistic displays as they die. In the case of low-mass stars like our Sun and M2-9 pictured here, the stars transform themselves from normal stars to white dwarfs by casting off their outer gaseous envelopes. The expended gas frequently forms an impressive display called a planetary nebula that fades gradually over thousands of years. M2-9, a butterfly planetary nebula 2100 light-years away shown in representative colors, has wings that tell a strange but incomplete tale. In the center, two stars orbit inside a gaseous disk 10 times the orbit of Pluto. The expelled envelope of the dying star breaks out from the disk creating the bipolar appearance. Much remains unknown about the physical processes that cause and shape planetary nebulae.

ASTRONOMY - When Z is for Mars

 2023 April 15

When Z is for Mars
Image Credit & Copyright: Tunc Tezel (TWAN)

Explanation: A composite of images captured about a week apart from mid August 2022 through late March 2023, this series traces the retrograde motion of ruddy-colored Mars. Progressing from lower right to upper left Mars makes a Z-shaped path as it wanders past the Pleiades and Hyades star clusters, through the constellation Taurus in planet Earth's night sky. Seen about every two years, Mars doesn't actually reverse the direction of its orbit to trace out the Z-shape though. Instead, the apparent backwards or retrograde motion with respect to the background stars is a reflection of the orbital motion of Earth itself. Retrograde motion can be seen each time Earth overtakes and laps planets orbiting farther from the Sun, the Earth moving more rapidly through its own relatively close-in orbit. High in northern hemisphere skies the Red Planet was opposite the Sun and at its closest and brightest on December 8, near the center of the frame. Seen close to Mars, a popular visitor to the inner Solar System, comet ZTF (C/2022 E3), was also captured on two dates, February 10 and February 16.

ASTRONOMY - Portrait of NGC 3628

2023 April 14

Portrait of NGC 3628
Image Credit: Image Credit & Copyright: Mike Selby & Mark Hanson

Explanation: Sharp telescopic views of NGC 3628 show a puffy galactic disk divided by dark dust lanes. Of course, this portrait of the magnificent, edge-on spiral galaxy puts some astronomers in mind of its popular moniker, the Hamburger Galaxy. It also reveals a small galaxy nearby (below), likely a satellite of NGC 3628, and a very faint but extensive tidal tail. The drawn out tail stretches for about 300,000 light-years, even beyond the left edge of the frame. NGC 3628 shares its neighborhood in the local universe with two other large spirals M65 and M66 in a grouping otherwise known as the Leo Triplet. Gravitational interactions with its cosmic neighbors are likely responsible for creating the tidal tail, as well as the extended flare and warp of this spiral's disk. The tantalizing island universe itself is about 100,000 light-years across and 35 million light-years away in the northern springtime constellation Leo. 

AERONAUTIQUE - Avions de légende - Messerschmitt Me 262

Cet éphémère chasseur-bombardier allemand, monoplace, de la seconde guerre mondiale, qui a volé entre 1944 et 1945, est le premier avion militaire à réaction. Les premiers essais ont lieu en 1941 (avec un moteur à pistons) et en 1942 avec deux réacteurs.

Les vitesses atteintes en opération dépassaient les 800 km/h. Plus rapide que n'importe quel autre avion de l'époque, le Me 262 était très difficile à abattre et efficace en attaque. Cependant, son autonomie était faible, à peine plus d'une heure, ce qui donnait une distance franchissable d'un millier de kilomètres au maximum, donc un rayon d'action bien inférieur à la moitié en opérations. Ses réacteurs délivraient une puissance faible à basses vitesses. Capricieux, ils réagissaient mal aux remises de gaz, parfois en s'éteignant. La maîtrise du ciel par les armées alliées à partir du printemps 1944 a rendu difficile l'exploitation du Me 262 par l'armée allemande.

© Noop1958, Wikimedia commons, DP

FuturaSciences