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20/09/2021

ASTRONOMY - Lynds Dark Nebula 1251

 2021 September 20

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

Lynds Dark Nebula 1251
Image Credit & Copyright: Cristiano Gualco

Explanation: Stars are forming in Lynds Dark Nebula (LDN) 1251. About 1,000 light-years away and drifting above the plane of our Milky Way galaxy, the dusty molecular cloud is part of a complex of dark nebulae mapped toward the Cepheus flare region. Across the spectrum, astronomical explorations of the obscuring interstellar clouds reveal energetic shocks and outflows associated with newborn stars, including the telltale reddish glow from scattered Herbig-Haro objects hiding in the image. Distant background galaxies also lurk on the scene, almost buried behind the dusty expanse. This alluring view spans over two full moons on the sky, or 17 light-years at the estimated distance of LDN 1251.

19/09/2021

ASTRONOMY - Rings and Seasons of Saturn

 021 September 19

The picture shows Saturn in yearly images taken from
2004 to 2015 from Earth. 
Please see the explanation for more detailed information.

Rings and Seasons of Saturn
Image Credit & CopyrightDamian Peach/SEN

Explanation: On Saturn, the rings tell you the season. On Earth, Wednesday marks an equinox, the time when the Earth's equator tilts directly toward the Sun. Since Saturn's grand rings orbit along the planet's equator, these rings appear most prominent -- from the direction of the Sun -- when the spin axis of Saturn points toward the Sun. Conversely, when Saturn's spin axis points to the side, an equinox occurs and the edge-on rings are hard to see from not only the Sun -- but Earth. In the featured montage, images of Saturn between the years of 2004 and 2015 have been superposed to show the giant planet passing from southern summer toward northern summer. Saturn was as close as it can get to planet Earth last month, and this month the ringed giant is still bright and visible throughout much of the night

AERONAUTIQUE - La reaversée de la Manche en flyboard


 

17/09/2021

ASTRONOMY - Video: Flash on Jupiter

 2021 September 17

Video: Flash on Jupiter
Video Credit & Copyright: T. Humbert, S. Barré, A. Desmougin & D. Walliang (Société Lorraine d'Astronomie), Astroqueyras

Explanation: There has been a flash on Jupiter. A few days ago, several groups monitoring our Solar System's largest planet noticed a two-second long burst of light. Such flashes have been seen before, with the most famous being a series of impactor strikes in 1994. Then, fragments of Comet Shoemaker-Levy 9 struck Jupiter leaving dark patches that lasted for months. Since then, at least seven impacts have been recorded on Jupiter -- usually discovered by amateur astronomers. In the featured video, variations in the Earth's atmosphere cause Jupiter's image to shimmer when, suddenly, a bright flash appears just left of center. Io and its shadow are visible on the right. What hit Jupiter will likely never be known, but considering what we do know of the nearby Solar System, it was likely a piece of rocky and ice -- perhaps the size of a bus -- that broke off long-ago from a passing comet or asteroid.

06/09/2021

ASTRONOMY - Firefly Milky Way over Russia

 2021 September 6

The picture shows an arching Milky Way Galaxy with a firefly 
path in the foreground over Russia.
Please see the explanation for more detailed information.

Firefly Milky Way over Russia
Image Credit & Copyright: Anton Komlev

Explanation: It started with a pine tree. The idea was to photograph a statuesque pine in front of the central band of our Milky Way Galaxy. And the plan, carried out two months ago, was successful -- they both appear prominently. But the resulting 3-frame panorama captured much more. Colorful stars, for example, dot the distant background, with bright Altair visible on the upper left. The planet Saturn, a bit closer, was captured just over the horizon on the far left. Just beyond the Earth's atmosphere, seen in the upper right, an Earth-orbiting satellite was caught leaving a streak during the 25-second exposure. The Earth's atmosphere itself was surprisingly visible -- as green airglow across the image top. Finally, just by chance, there was a firefly. Do you see it? Near the image bottom, the firefly blinked in yellow several times as it fluttered before the rolling hills above Milogradovka River in Primorsky KraiRussia.

04/09/2021

POURQUOI - Pourquoi rêve-t-on ?


Il s'agit de quelque chose de nécessaire à la vie. Il semblerait que sans cela nous mourons. Nous avons donc besoin de le faire afin que notre cerveau effectue sa "maintenance quotidienne".

Lorsque l'on dort, il nous arrive de rêver. Certains se voient en train de chevaucher des licornes, d'autre volent. Il y en a même qui se prennent pour des flamants roses. Bref, ils sont parfois étranges et il nous est bien difficile de les interpréter lorsque l'on se réveille. Mais au fait, pourquoi rêve-t-on ?

En fait, il nous faut commencer par le début et comprendre le sommeil. Ce dernier a une fonction réparatrice et récupératrice. Il possède trois phases, qui forment un cycle : le sommeil lent léger, le sommeil lent lourd et enfin le sommeil paradoxal (période de rêves).
Chaque cycle dure environ 1 h 30 à 2 h, donc nous rêvons plusieurs fois dans la nuit. Selon le moment où l'on se réveille, on peut s'en rappeler ou non (un phénomène que nous vous détaillons dans cet article). On peut comparer notre cerveau à un ordinateur dans ce cas, le rêve ayant une fonction de défragmentation. En d'autres termes, on peut dire qu'au cours du rêve, nos souvenirs se mettent en place. Chez les bébés, il sert à mettre en place la mémoire. D'ailleurs, plus on vieillit, moins on rêve.

Il est encore peu connu, mais sa fonction principale est de réorganiser les souvenirs et connaissances que nous avons accumulés dans la journée. Il peut aussi évoquer des malaises que l'on a dans la vie, tout comme nos bonheurs quotidiens. Ils sont l'expression la plus claire de ce que nous sommes.

ASTRONOMY - A Falcon 9 Nebula

 2021 September 4

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

A Falcon 9 Nebula
Image Credit & CopyrightDennis Huff

Explanation: Not the Hubble Space Telescope's latest view of a distant galactic nebula, this illuminated cloud of gas and dust dazzled early morning spacecoast skygazers on August 29. The snapshot was taken at 3:17am from Space View Park in Titusville, Florida. That's about 3 minutes after the launch of a SpaceX Falcon 9 rocket on the CRS-23 mission to resupply the International Space Station. It captures drifting plumes and exhaust from the separated first and second stage of the rocket rising through still dark skies. The lower bright dot is the second stage continuing on to low Earth orbit. The upper one is the rocket's first stage performing a boostback burn. Of course the first stage booster returned to make the first landing on the latest autonomous drone ship to arrive in the Atlantic, A Short Fall of Gravitas.

02/09/2021

ASTRONOMY - M51: The Whirlpool Galaxy

 2021 September 2

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

M51: The Whirlpool Galaxy
Image Credit & CopyrightJosep Drudis

Explanation: Find the Big Dipper and follow the handle away from the dipper's bowl until you get to the last bright star. Then, just slide your telescope a little south and west and you'll come upon this stunning pair of interacting galaxies, the 51st entry in Charles Messier's famous catalog. Perhaps the original spiral nebula, the large galaxy with well defined spiral structure is also cataloged as NGC 5194. Its spiral arms and dust lanes clearly sweep in front of its companion galaxy (top), NGC 5195. The pair are about 31 million light-years distant and officially lie within the angular boundaries of the small constellation Canes Venatici. Though M51 looks faint and fuzzy to the eye, deep images like this one reveal its striking colors and galactic tidal debris.

01/09/2021

ASTRONOMY - Dancing Ghosts: Curved Jets from Active Galaxies

2021 September 1
The picture shows the radio jets emitted from distant active galaxies.
The jets, made of electrons, appear like dancing ghosts.
Please see the explanation for more detailed information.

Dancing Ghosts: Curved Jets from Active Galaxies
Image Credit: Jayanne English & Ray NorrisEMU-ASKAPDESText: Jayanne English (U. Manitoba)

Explanation: Why would galaxies emit jets that look like ghosts? And furthermore, why do they appear to be dancing? The curled and fluffy jets from the supermassive black holes at the centers of two host galaxies (top center and lower left) are unlike anything seen before. They were found by astronomers using the Australian Square Kilometer Array Pathfinder (ASKAP) radio telescope when creating maps tracing the evolution of galaxies. Images preceding this Evolutionary Map of the Universe survey only showed amorphous blobs. Eventually, comparisons of relative amounts of energy emitted revealed the glowing elongated structures were created by electrons streaming around magnetic field lines. Overlaying the radio data on an optical view of the sky (Dark Energy Survey) confirmed that the electron streams originated from the centers of active galaxies. Usually such Active Galactic Nuclei (AGN) produce straight jets. A leading hypothesis for the geometric origin of these unusually graceful shapes involves the flow of large-scale intergalactic winds

BIOMES - Autriche

Les belles couleurs automnales des forêts tempérées d’Autriche FuturaSciences