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26/06/2022

OVNI - Espirais de luz azul no céu da Nova Zelândia

Eram 19h25 de domingo quando Alasdair Burns, guia de observação de estrelas na Ilha Stewart, Nova Zelândia, recebeu uma mensagem de um amigo a pedir que fosse olhar para o céu. Burns saiu de casa e testemunhou uma enorme espiral azul de luz no meio da escuridão do céu. “Parecia uma enorme galáxia em espiral, ali a pairar no céu e a atravessá-lo lentamente. Foi uma sensação muito estranha”, confessa, citado pelo The Guardian.

Depois de ter observado o fenómeno durante uns segundos, rapidamente se lembrou de eternizar o momento e capturou algumas imagens.

Richard Easther, físico na Universidade de Auckland, explicou ao jornal que são formadas nuvens desta natureza quando um foguetão leva um satélite para a órbita da terra. “Quando o combustível propulsor é ejetado, o que temos essencialmente é água e dióxido de carbono, que formam uma nuvem iluminada pelo sol”, começa por explicar.

“A combinação da geometria da trajetória da órbita do satélite e da forma como nós estamos posicionados em relação ao Sol foi o que foi capaz de produzir estas nuvens esquisitas que eram visíveis da Ilha Sul”, acrescenta o físico.

O “espetáculo” observado terá sido provocado pelo lançamento do satélite da Globalstar a cargo da SpaceX, que foi enviado para uma órbita mais baixa a partir do Cabo Canaveral, na Flórida.

Visão

25/06/2022

ASTRONOMY - Planets of the Solar System

 2022 June 25

See Explanation.  Clicking on the picture will download
the highest resolution version available.

Planets of the Solar System
Image Credit & CopyrightAntonio Canaveras, Chiara Tronci, Giovanni Esposito, Giuseppe Conzo, Luciana Guariglia, (Gruppo Astrofili Palidoro)

Explanation: Simultaneous images from four cameras were combined to construct this atmospheric predawn skyscape. The cooperative astro-panorama captures all the planets of the Solar System, just before sunrise on June 24. That foggy morning found innermost planet Mercury close to the horizon but just visible against the twilight, below and left of brilliant Venus. Along with the waning crescent Moon, the other bright naked-eye planets, Mars, Jupiter, and Saturn lie near the ecliptic, arcing up and to the right across the wide field of view. Binoculars would have been required to spot the much fainter planets Uranus and Neptune, though they also were along the ecliptic in the sky. In the foreground are excavations at an ancient Roman villa near Marina di San Nicola, Italy, planet Earth.

24/06/2022

ASTRONOMY - Filaprom on the Western Limb

 2022 June 24

See Explanation.  Clicking on the picture will download
the highest resolution version available.

Filaprom on the Western Limb
Image Credit & CopyrightMartin Wise

Explanation: A solar filament is an enormous stream of incandescent plasma suspended above the active surface of the Sun by looping magnetic fields. Seen against the solar disk it looks dark only because it's a little cooler, and so slightly dimmer, than the solar photosphere. Suspended above the solar limb the same structure looks bright when viewed against the blackness of space and is called a solar prominence. A filaprom would be both of course, a stream of magnetized plasma that crosses in front of the solar disk and extends beyond the Sun's edge. In this hydrogen-alpha close-up of the Sun captured on June 22active region AR3038 is near the center of the frame. Active region AR3032 is seen at the far right, close to the Sun's western limb. As AR3032 is carried by rotation toward the Sun's visible edge, what was once a giant filament above it is now partly seen as a prominence, How big is AR3032's filaprom? For scale planet Earth is shown near the top right corner.

23/06/2022

MERVEILLEUX MONDE SOUS-MARIN - Le dugon


Egypte : Mer Rouge : Region de Marsa Alam.

Le dugong (Dugong dugong) vit dans les eaux côtières peu profondes et chaudes de la mer Rouge et de l'océan Indien ainsi que dans le Pacifique.

Incapable de se défendre contre un quelconque prédateur, il choisit souvent, pour se dissimuler, de vivre dans des zones où la visibilité est assez mauvaise. Très bon apnéiste, il peut rester sous l'eau plus de 15 minutes, avant de remonter respirer en surface.

Le male, plus gros que la femelle, peut mesurer trois mètres de long et peser 200 kilos. Il est en général accompagné de remoras, et de carangues royales juvèniles.

Herbivore, il se nourrit de phanerogames.

Inscrits à l'annexe 1 de la CITES depuis la confèrence de Nairobi en avril 2000, ce qui en interdit le commerce, les dugongs ou vaches marines continuent pourtant a être gravement menacés, notamment par la disparition des herbiers qui leur servent d'habitat.

© Alexis Rosenfeld

METEO EXTREME - L’éclair le plus long

 

Les éclairs ne s’étendent généralement pas sur une distance de plus de 12 kilomètres et ne durent que quelques centièmes de seconde. © Jean-Marie Muggianu, Flickr, CC by-NC-ND 2.0

Selon les experts de l'OMM, un éclair enregistré en juin 2007 dans l'Oklahoma a parcouru une distance record de 321 kilomètres. Généralement, la longueur d'un éclair se situe aux alentours de 12 kilomètres...

Quant à l'éclair qui a duré le plus longtemps, il a été enregistré dans le sud de la France - du côté de la Drôme pour être plus précis - en août 2012. Il a duré pas moins de 7,74 secondes alors que la plupart des éclairs ne brillent pas plus de quelques centièmes de seconde.

FuturaSciences

ASTRONOMY - Spiral Galaxy NGC 6744

 2022 June 23

See Explanation.  Clicking on the picture will download
the highest resolution version available.

Spiral Galaxy NGC 6744
Image Credit & CopyrightBasudeb Chakrabarti

Explanation: Beautiful spiral galaxy NGC 6744 is nearly 175,000 light-years across, larger than our own Milky Way. It lies some 30 million light-years distant in the southern constellation Pavo but appears as only a faint, extended object in small telescopes. We see the disk of the nearby island universe tilted towards our line of sight in this remarkably detailed galaxy portrait, a telescopic view that spans an area about the angular size of a full moon. In it, the giant galaxy's elongated yellowish core is dominated by the light from old, cool stars. Beyond the core, grand spiral arms are filled with young blue star clusters and speckled with pinkish star forming regions. An extended arm sweeps past smaller satellite galaxy NGC 6744A at the lower right. NGC 6744's galactic companion is reminiscent of the Milky Way's satellite galaxy the Large Magellanic Cloud.

22/06/2022

ASTRONOMY - Supernova Remnant: The Veil Nebula

 2022 June 22

The featured image shows a composite of long duration
exposures of he Veil Nebula, the glowing gaseous remnants of
a supernova that occurred about ten thousand years ago.
Please see the explanation for more detailed information.

Supernova Remnant: The Veil Nebula
Image Credit & Copyright: Craig Stocks (Utah Desert Remote Observatories)

Explanation: Ten thousand years ago, before the dawn of recorded human history, a new light would have suddenly have appeared in the night sky and faded after a few weeks. Today we know this light was from a supernova, or exploding star, and record the expanding debris cloud as the Veil Nebula, a supernova remnant. Imaged with color filters featuring light emitted by sulfur (red), hydrogen (green), and oxygen (blue), this deep wide-angle view was processed to remove the stars and so better capture the impressive glowing filaments of the Veil. Also known as the Cygnus Loop, the Veil Nebula is roughly circular in shape and covers nearly 3 degrees on the sky toward the constellation of the Swan (Cygnus). Famous nebular sections include the Bat Nebula, the Witch's Broom Nebula, and Fleming's Triangular Wisp. The complete supernova remnant lies about 1,400 light-years away.

ASTROPHOTOGRAPHIE - Éclipse hybride du Soleil


D'Eugen Kamenew (Allemagne) cette magnifique composition « Hybrid Solar Eclipse 2 » mettant en scène, dans le nord du Kenya, le jour de l'éclipse hybride du Soleil du 3 novembre 2013, Geoffrey Lowa et une barque solaire. Sur la pointe du rocher, l'homme embarque à la fin du jour, dans un croissant lumineux, notre étoile en partie occultée par la Lune.

© Eugen Kamenew, Flickr

21/06/2022

ASTRONOMY - Analemma over Taipei

 2022 June 21

The featured image shows the Sun in many positions as 
it appeared during the late afternoon. In the foreground is
the skyline of the city including Taipei 101, one of the 
tallest buildings in the world. 
Please see the explanation for more detailed information.

Analemma over Taipei
Image Credit & Copyright: Meiying Lee

Explanation: Does the Sun return to the same spot on the sky every day? No. A better and more visual answer to that question is an analemma, a composite of images taken at the same time and from the same place over the course of a year. The featured analemma was compiled at 4:30 pm many afternoons from Taiwan during 2021, with the city skyline of Taipei in the foreground, including tall Taipei 101. The Sun's location in December -- at the December solstice -- is shown on the far left, while its location at the June solstice is captured on the far right. Also shown are the positions of the Sun throughout the rest of the day on the solstices and equinoxes. Today is the June solstice of 2022, the day in Earth's northern hemisphere when the Sun spends the longest time in the sky. In many countries, today marks the official beginning of a new season, for example winter in Earth's southern hemisphere.

20/06/2022

ASTRONOMY - Rock Fingers on Mars

 2022 June 20

The featured image shows finger-like spires extending
from a larger rock on Mars. 
Please see the explanation for more detailed information.

Rock Fingers on Mars
Image Credit: NASAJPL-CaltechMSSS

Explanation: There, just right of center, what is that? The surface of Mars keeps revealing new surprises with the recent discovery of finger-like rock spires. The small nearly-vertical rock outcrops were imaged last month by the robotic Curiosity rover on Mars. Although similar in size and shape to small snakes, the leading explanation for their origin is as conglomerations of small minerals left by water flowing through rock crevices. After these relatively dense minerals filled the crevices, they were left behind when the surrounding rock eroded away. Famous rock outcrops on Earth with a similar origin are called hoodoos. NASA's Curiosity Rover continues to search for new signs of ancient water in Gale Crater on Mars, while also providing a geologic background important for future human exploration.

BIOMES - La Corse

La Corse, au cœur de l’environnement méditerranéen FuturaSciences