ACTIVITE SOLAIRE : Une tempête de très grande amplitude

Les scientifiques surveillent le Soleil de près. Un peu plus, même, ces dernières semaines. Parce qu'il semble être entré dans une phase tout particulièrement active.

La tempête a été classée G4 sur une échelle qui compte 5 niveaux. Les experts estiment que de tels événements peuvent se produire une centaine de fois par cycle solaire. Et cette tempête était bel et bien la plus puissante des tempêtes géomagnétiques enregistrées depuis six ans.

Pendant quelque 24 heures, le bouclier magnétique de la Terre s'est fendu. Des dommages ont pu être causés à des satellites, des incidents enregistrés sur les réseaux électriques, des perturbations apparaître sur les réseaux GPS ou encore des blackouts se faire sur les transmissions radio. Les scientifiques recueillent toujours des informations à ce sujet en ce moment même.

Elle a aussi donné naissance à de nombreuses et merveilleuses aurores boréales jusque dans le Nouveau-Mexique (États-Unis). Elles ont aussi été vues en Europe.

Les experts estiment aujourd'hui que des aurores boréales pourraient encore être observées dans les heures qui viennent aux latitudes moyennes. Alors, ouvrez l'oeil...

FuturaSciences

ASTRONOMY - Wanderers

 2023 March 26

Wanderers
Video Credit: Visuals: Erik Wernquist; Music: Christian Sandquist; Words & Voice: Carl Sagan

Explanation: How far out will humanity explore? If this video's fusion of real space imagery and fictional space visualizations is on the right track, then at least the Solar System. Some of the video's wondrous sequences depict future humans drifting through the rings of Saturn, exploring Jupiter from a nearby spacecraft, and jumping off a high cliff in the low gravity of a moon of Uranus. Although no one can know the future, wandering and exploring beyond boundaries -- both physical and intellectual -- is part of the human spirit and has frequently served humanity well in the past.

ASTRONOMY - Venus and the Da Vinci Glow

 2023 March 25

Venus and the Da Vinci Glow
Image Credit & Copyright: Giorgia Hofer

Explanation: On March 23 early evening skygazers could watch Venus and a young crescent moon, both near the western horizon. On that date Earth's brilliant evening star, faint lunar night side and slender sunlit crescent were captured in this telephoto skyscape posing alongside a church tower from Danta di Cadore, Dolomiti, Italy. Of course the subtle lunar illumination is earthshine, earthlight reflected from the Moon's night side. 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. On March 24, from some locations the Moon could be seen to occult or pass in front of Venus. Around the planet tonight, a waxing lunar crescent will appear near the Pleiades star cluster.

ASTRONOMY - Dark Nebulae and Star Formation in Taurus

 2023 March 21

Dark Nebulae and Star Formation in Taurus
Image Credit & Copyright: Vikas Chander

Explanation: Can dust be beautiful? Yes, and it can also be useful. The Taurus molecular cloud has several bright stars, but it is the dark dust that really draws attention. The pervasive dust has waves and ripples and makes picturesque dust bunnies, but perhaps more importantly, it marks regions where interstellar gas is dense enough to gravitationally contract to form stars. In the image center is a light cloud lit by neighboring stars that is home not only to a famous nebula, but to a very young and massive famous star. Both the star, T Tauri, and the nebula, Hind's Variable Nebula, are seen to vary dramatically in brightness -- but not necessarily at the same time, adding to the mystery of this intriguing region. T Tauri and similar stars are now generally recognized to be Sun-like stars that are less than a few million years old and so still in the early stages of formation. The featured image spans about four degrees not far from the Pleiades star cluster, while the featured dust field lies about 400 light-years away.

ASTRONOMY - M1: The Expanding Crab Nebula

 2023 March 20

M1: The Expanding Crab Nebula
Video Credit & Copyright: Detlef Hartmann

Explanation: Are your eyes good enough to see the Crab Nebula expand? The Crab Nebula is cataloged as M1, the first on Charles Messier's famous list of things which are not comets. In fact, the Crab is now known to be a supernova remnant, an expanding cloud of debris from the explosion of a massive star. The violent birth of the Crab was witnessed by astronomers in the year 1054. Roughly 10 light-years across today, the nebula is still expanding at a rate of over 1,000 kilometers per second. Over the past decade, its expansion has been documented in this stunning time-lapse movie. In each year from 2008 to 2022, an image was produced with the same telescope and camera from a remote observatory in Austria. The sharp, processed frames even reveal the dynamic energetic emission surrounding the rapidly spinning pulsar at the center. The Crab Nebula lies about 6,500 light-years away toward the constellation of the Bull (Taurus).

ASTRONOMY - Equinox at the Pyramid of the Feathered Serpent

 2023 March 19

Equinox at the Pyramid of the Feathered Serpent
Image Credit & Copyright: Robert Fedez

Explanation: To see the feathered serpent descend the Mayan pyramid requires exquisite timing. You must visit El Castillo -- in Mexico's Yucatán Peninsula -- near an equinox. Then, during the late afternoon if the sky is clear, the pyramid's own shadows create triangles that merge into the famous illusion of a slithering viper. Also known as the Temple of Kukulkan, the impressive step-pyramid stands 30 meters tall and 55 meters wide at the base. Built up as a series of square terraces by the pre-Columbian civilization between the 9th and 12th century, the structure can be used as a calendar and is noted for astronomical alignments. The featured composite image was captured in 2019 with Jupiter and Saturn straddling the diagonal central band of our Milky Way galaxy. Tomorrow marks another equinox -- not only at Temple of Kukulcán, but all over planet Earth.

ASTRONOMIE - Vénus flirte avec le fin croissant de Lune au crépuscule

 Cette attrayante rencontre est à admirer tout au long de la soirée du 24 mars 2023.

Positions de la Lune, de Vénus et de Jupiter vers 19h30 (heure de Paris) le 24 mars 2023. Le cercle bleu a un champ de six degrés typique d’une paire de jumelles 10×50.

Elle est désormais bien installée dans le ciel du soir, vers l’ouest : Vénus surpasse tous les astres alentours avec son éclat intense. Dans la soirée du 24 mars, la planète connue aussi sous le nom d’étoile du Berger doit pourtant partager la vedette avec la Lune. Avec son fin croissant âgé d’environ trois jours et sa lumière cendrée, notre satellite est aussi très attrayant.

Et c’est un régal pour les yeux de se tourner vers l’ouest à partir de 19h30 (heure de Paris) ! Vénus et la Lune sont éloignés d’un peu plus de trois degrés, une proximité qui les rend aussi observables ensemble dans une paire de jumelles classique. Vers 19h30 justement et si votre horizon est parfaitement dégagé, recherchez également la planète Jupiter, au ras de l’horizon. Mais cette dernière disparaît bien vite, laissant le champ libre à nos deux vedettes qui resplendissent de plus en plus à mesure que le ciel s’assombrit. Si vous ne pouvez pas quitter des yeux ce magnifique duo qui s’abaisse progressivement, sachez que vous pourrez en profiter jusqu’aux environs de 22h30 !

Stelvision

ASTRONOMY - The Medusa Nebula

 023 March 17

The Medusa Nebula
Image Credit & Copyright: Martin Bradley Chesterfield Astronomical Society

Explanation: Braided and serpentine filaments of glowing gas suggest this nebula's popular name, The Medusa Nebula. Also known as Abell 21, this Medusa is an old planetary nebula some 1,500 light-years away in the constellation Gemini. Like its mythological namesake, the nebula is associated with a dramatic transformation. The planetary nebula phase represents a final stage in the evolution of low mass stars like the sun as they transform themselves from red giants to hot white dwarf stars and in the process shrug off their outer layers. Ultraviolet radiation from the hot star powers the nebular glow. The Medusa's transforming star is the faint one near the center of the overall bright crescent shape. In this deep telescopic view, fainter filaments clearly extend below and right of the bright crescent region. The Medusa Nebula is estimated to be over 4 light-years across.

ASTRONOMY - Saturn's Hyperion: A Moon with Odd Craters

 2023 March 12

Saturn's Hyperion: A Moon with Odd Craters
Image Credit: NASA, ESA, JPL, SSI, Cassini Imaging Team

Explanation: What lies at the bottom of Hyperion's strange craters? To help find out, the robot Cassini spacecraft that once orbited Saturn swooped past the sponge-textured moon and took images of unprecedented detail. A six-image mosaic from the 2005 pass, featured here in scientifically assigned colors, shows a remarkable world strewn with strange craters and an odd, sponge-like surface. At the bottom of most craters lies some type of unknown dark reddish material. This material appears similar to that covering part of another of Saturn's moons, Iapetus, and might sink into the ice moon as it better absorbs warming sunlight. Hyperion is about 250 kilometers across, rotates chaotically, and has a density so low that it likely houses a vast system of caverns inside.

ASTRONOMY - Rainbow Tree

 2023 March 13

Rainbow Tree
Image Credit & Copyright: Eric Houck

Explanation: What lies at the end of a rainbow? Something different for everyone. For the photographer taking this picture, for example, one end of the rainbow ended at a tree. Others nearby, though, would likely see the rainbow end somewhere else. The reason is because a rainbow's position depends on the observer. The center of a rainbow always appears in the direction opposite the Sun, but that direction lines up differently on the horizon from different locations. This rainbow's arc indicates that its center is about 40 degrees to the left and slightly below the horizon, while the Sun is well behind the camera and just above the horizon. Reflections and refractions of sunlight from raindrops in a distant storm in the direction of the rainbow are what causes the colorful bands of light. This single exposure image was captured in early January near Knight's Ferry, California, USA.