Géoglyphes - LES LIGNES DE NAZCA AU PEROU

Les géoglyphes de Nazca, encore appelés lignes de Nazca, sont de grandes figures tracées dans le désert de Nazca, dans le sud du Pérou. Réalisés pour la plupart entre -200 et 600 ap. J.-C., ils sont le fait de la civilisation Nazca, une culture pré-inca qui se développa entre 300 av. J.-C. et 800 de notre ère. On se perd en conjectures et spéculations parfois douteuses quant à la signification que ces figures avaient pour les Nazcas.

Le sol sur lequel se dessinent ces géoglyphes est couvert de cailloux que l'oxyde de fer colore en rouge. Et c'est en les ôtant, parfois sur des kilomètres, que les Nazcas ont révélé un sol gypseux grisâtre, faisant apparaître des figures réparties le long d'une ligne de 50 km reliant les villes de Nazca et de Palpa, dans la région d'Ica.

Les géoglyphes de Nazca, représentant souvent des animaux stylisés, sont parfois de simples lignes longues de plusieurs kilomètres.

© Diego Delso, CC by-sa 4.0

Astronomy - DUELING BANDS OVER THE ATACAMA DESERT

 2026 July 6

Dueling Bands over the Atacama Desert
Image Credit & Copyright: Julien Looten

Explanation: What are these two bands in the sky? The more commonly seen band is on the left and is the central band of our Milky Way galaxy. Our Sun orbits in the disk of this spiral galaxy so that from inside, it appears as a band of comparable brightness all the way around the sky. The less commonly seen band, on the right, is zodiacal light -- sunlight reflected from dust orbiting the Sun in our Solar System. Zodiacal light is brightest near the Sun and so is best seen just before sunrise or just after sunset. On some evenings, this ribbon of zodiacal light can appear quite prominent. It was discovered only in this century that zodiacal dust was mostly expelled by comets that have passed near Jupiter. The featured image was captured about a year ago from the Atacama Desert in Chile.

Astronomy - AR 4478 : GIANT SUNSPOT GROUP

 2026 June 28

AR 4478: Giant Sunspot Group
Image Credit & Copyright: Alfredo Vidal Pérez

Explanation: Right now, one of the largest sunspot groups in recent history is crossing the Sun. Active Region 4478 is not only big -- it's violent, showing tangled magnetic fields capable of throwing off huge clouds of particles into the Solar System. Some of these CMEs might impact the Earth. At the extreme, these solar storms could cause some Earth-orbiting satellites to malfunction, the Earth's atmosphere to slightly distort, and electrical power grids to surge. When impacting Earth's upper atmosphere, these particles can produce beautiful auroras. Pictured here, AR 4478 and its dark sunspots were captured in visible light a few days ago from Barcelona, Spain. Almost as large as AR 3664 was in 2024, the AR 4478 sunspot group is so big that it is visible just with glasses specially designed to view solar eclipses. This week, skygazing enthusiasts all over the globe will not only be tracking AR 4478 during the day -- but keenly watching night skies for its corresponding bright auroras.

Astronomy - M82: GALAXY WITH A SUPERGALACTIC WIND

 2026 June 29

M82: Galaxy with a Supergalactic Wind
Image Credit: NASA, ESA, CSA, A. Smercina (STScI, Tufts), T. Williams (U. Manchester); Image Processing: A. Pagan (STScI)

Explanation: Why is the Cigar Galaxy billowing red smoke? M82, as this starburst galaxy is also known, was stirred up by a recent pass near large spiral galaxy M81. This doesn't fully explain the source of the red-glowing outwardly expanding gas and dust, however. Evidence indicates that this gas and dust is being driven out by the combined emerging particle winds of many stars, together creating a galactic superwind. The dust particles are thought to originate in M82's interstellar medium and are actually similar in size to particles in cigar smoke. The featured photographic mosaic combines images taken in visible light from the Hubble Space Telescope and images taken in infrared light from James Webb Space Telescope. It shows the light-colored central galaxy nearly edge on across the image center with tremendous orange and red colored filaments of gas and dust extending both up and down. The filaments extend for over 10,000 light years. The 12-million light-year distant Cigar Galaxy is the brightest galaxy in the sky in infrared light and can be seen in visible light with a small telescope towards the constellation of the Great Bear (Ursa Major).

Astronomy - UNUSUALLY SMOOTH SECTIONS OF ASTEROID ITOKAWA

 2026 June 30

Unusually Smooth Sections of Asteroid Itokawa
Image Credit: JAXA, ISAS

Explanation: Why are parts of this asteroid's surface so smooth? The answer seems likely to do with the dynamics of an asteroid that is a loose pile of rubble rather than a solid rock. The unusual asteroid Itokawa was visited by the Japanese spacecraft Hayabusa in 2005 which imaged and documented its unusual structure and mysterious lack of craters. Analyses of the border regions between smooth and rugged sections indicate that jostling of the asteroid might be creating segregation between large and small rocks near the surface, like the Brazil nut effect. The robotic Hayabusa actually touched down on one of the smooth patches, dubbed the MUSES Sea, and collected soil samples. These samples were returned to Earth and are not only giving clues to the ancient history of this unusual asteroid, but also about the early years of our entire Solar System. Computer simulations show that 500-meter asteroid Itokawa may impact the Earth within the next few million years.

Rocking Space: Today is Astero

Astronomy - MARS MARATHON BY PERSEVERANCE

2026 June 27

Mars Marathon by Perseverance
Image Credit: NASA, LPL (U. Arizona), MRO, HiRISE

Explanation: In this recent HiRISE view from the Mars Reconnaissance Orbiter, the little green dot indicated on the surface of the big Red Planet is the Perseverance Mars rover. Recorded on June 13, the car-sized, six-wheeled robot was imaged a day before completing a Martian marathon, traveling a total distance of 26.218 miles (42.195 kilometers) since it began exploring the surface of Mars. That equivalent marathon distance was achieved by Perseverance on its mission sol (Martian day) 1,890, after about 5 Earth years and 4 Earth months of driving. Perseverance is continuing to hunt for biosignatures. In the HiRISE image, the Mars rover's tracks can be seen leading to its location in an area west of its landing site in Jezero crater near an ancient river delta. 

Géoglyphes - L'HOMME DE MARREE EN AUSTRALIE

L'Homme de Marree est un géoglyphe situé sur un plateau à Finnis Springs, 60 km à l'ouest de la ville de Marree, dans le centre de l'Australie-Méridionale. Long de 4,2 km, il semble représenter un aborigène d'Australie chassant les oiseaux à l'aide d'un bâton à lancer. Il n’a été découvert qu’en 1998 à l’aide d’un avion et son origine est inconnue. Elle pourrait être moderne et due à un artiste non aborigène.

© Peter Campbell, CC by-sa 3.0

La vie et la mort - Y-A-T-IL UNE VIE APRèS LA MORT ? (5/5)

Entre hypothèses médicales et questions philosophiques

Les sceptiques avancent plusieurs explications : libération massive de neurotransmetteurs, manque d’oxygène, constructions mémorielles a posteriori. Cependant, aucune hypothèse ne permet aujourd’hui d’expliquer de manière satisfaisante l’ensemble des cas documentés, en particulier lorsque l’activité cérébrale est quasi nulle. Le témoignage d’Eben Alexander ne constitue pas une preuve scientifique définitive d’une vie après la mort. Il représente toutefois un élément troublant, venant d’un spécialiste du cerveau lui-même, qui reconnaît les limites actuelles de la science.

Une question toujours ouverte

Aujourd’hui encore, Eben Alexander affirme ne pas chercher à imposer une croyance, mais à ouvrir un débat. Son expérience soulève une interrogation essentielle : la conscience humaine est-elle strictement limitée au fonctionnement biologique du cerveau, ou existe-t-il une dimension encore inconnue ? Entre science, médecine et philosophie, la question reste ouverte. Mais une chose est certaine : lorsqu’un neurochirurgien remet en cause ses propres certitudes après avoir frôlé la mort, le sujet mérite d’être examiné avec sérieux.

CommentEconomiser

La vie et la mort - Y-A-T-IL UNE VIE APRèS LA MORT ? (4/5)

Une remise en question scientifique

Après sa guérison, Eben Alexander analyse son propre dossier médical. Il constate que, selon les connaissances actuelles en neurosciences, son cerveau n’était pas en état de produire une telle expérience. Pour lui, cette contradiction est centrale. 

En 2012, il publie un ouvrage dans lequel il détaille son coma, son expérience et ses réflexions. Le livre devient rapidement un best-seller international et suscite un débat intense entre neurologues, philosophes et chercheurs en sciences cognitives. D’autres chercheurs s’y intéressent Eben Alexander n’est pas un cas isolé.

Depuis les années 1970, des chercheurs comme Raymond Moody, psychiatre américain, étudient les expériences de mort imminente. Raymond Moody a notamment documenté des témoignages de patients capables de décrire avec précision des événements survenus pendant leur mort clinique, parfois malgré des handicaps sensoriels majeurs. 

Pour ces chercheurs, ces récits posent une question fondamentale : la conscience ou l'âme pourraient-elles exister indépendamment du cerveau ?

CommentEconomiser

.../>

Astronomy - M27 : THE DUMBBELL NEBULA

 2026 June 22

M27: The Dumbbell Nebula
Image Credit & Copyright: Francesco Antonucci

Explanation: Is this what will become of our Sun? Quite possibly. The first hint of our Sun's future was discovered inadvertently in 1764. At that time, Charles Messier was compiling a list of diffuse objects not to be confused with comets. The 27th object on Messier's list, now known as M27 or the Dumbbell Nebula, is a planetary nebula, one of the brightest planetary nebulas on the sky and visible with binoculars toward the constellation of the Fox (Vulpecula). It takes light about 1000 years to reach us from M27, featured here in colors enhanced by red for hydrogen and blue for oxygen. We now know that in about 6 billion years, our Sun will shed its outer gases into a planetary nebula like M27, while its remaining center will become an X-ray hot white dwarf star. Understanding the physics and significance of M27 was well beyond 18th century science, though. Even today, many things remain mysterious about planetary nebulas, including how their intricate shapes are created.