Vulcanologie - POPOCATAPL (MEXIQUE)

Avec 5,458 mètres, c'est le deuxième plus grand volcan d'Amérique du nord.

©Getty Images

Astronomy - MESSIER 104

 2026 May 29

Messier 104
Image Credit: CTIO, NOIRLab, DOE, NSF, AURA;
Image Processing: T. A. Rector (U. Alaska Anchorage), D. de Martin (NSF’s NOIRLab) & M. Zamani (NSF, NOIRLab)

Explanation: A gorgeous spiral galaxy, Messier 104 is famous for its nearly edge-on profile featuring a broad ring of obscuring dust lanes. Seen in silhouette against an extensive central bulge of stars, the swath of cosmic dust lends a broad brimmed hat-like appearance to the galaxy suggesting a more popular moniker, the Sombrero Galaxy. Also known as NGC 4594, the Sombrero galaxy can be seen across the spectrum and is host to a central supermassive black hole. About 50,000 light-years across and 28 million light-years away, M104 is one of the largest galaxies at the southern edge of the Virgo Galaxy Cluster. Still, the spiky foreground stars in this field of view lie well within our own Milky Way. This broad view of the well-known galaxy was processed to reveal M104's extended halo, as well as a faint tidal stellar stream. It was captured by the Dark Energy Camera (DECam) on the Blanco 4-meter telescope at the Cerro Tololo Inter-American Observatory.

Musique - JAKUB NIEWIADOMSKI - BACH - 5 MINI-PIECES

Astronomy - NGC 1514 : THE CRYSTAL BALL NEBULA

 2026 May 28

NGC 1514: The Crystal Ball Nebula
Image Credit: International Gemini Observatory/NOIRLab/NSF/AURA; Image Processing: J. Miller & M. Rodriguez (International Gemini Observatory/NSF NOIRLab), T.A. Rector (University of Alaska Anchorage/NSF NOIRLab), D. de Martin & M. Zamani (NSF NOIRLab)
Text: Cecilia Chirenti (NASA GSFC, UMCP, CRESST II)

Explanation: What do you see in this crystal ball? The featured image shows NGC 1514, known as the Crystal Ball Nebula, observed by the Gemini North telescope on Maunakea, in Hawai'i. NGC 1514 is 1,500 light-years away and was discovered by William Herschel in 1790. This planetary nebula is formed when a star becomes a red giant and ejects its outer gas layers. The ejected shell of gas is heated up by the core of the star to temperatures hotter than the surface of our Sun: that makes the gas shine, creating beautiful images like this one. The slightly asymmetrical shape of the Crystal Ball Nebula reveals a secret: the bright star in the center has a companion. As the two stars orbit each other with a period of about nine years, they shape the gas around them. In about 10,000 - 25,000 years the nebula will be dissipated by their stellar winds.

Géoglyphes - LE CHANDELIER DE PARACAS AU PEROU

Le Chandelier de Paracas (en espagnol : el Candelabro de Paracas) est un géoglyphe à flanc de colline, à 150 mètres de la côte nord de la péninsule de Paracas, une péninsule désertique dans le sud du Pérou à près de 200 km de la capitale Lima.

Quasiment orienté nord-sud, il a la forme d'une sorte de candélabre d'environ 180 mètres de long pour une largeur de 70 mètres. Il a été réalisé en creusant des tranchées dans un sol sableux sur 50 cm de profondeur et en plaçant des pierres sur son pourtour. L'époque de construction du Chandelier n'est pas connue, pas plus que les auteurs du géoglyphe ni leurs motifs.

© Alex Zanuccoli, CC by-sa 2.0 ; abogawat, CC0

Astronomy - PK 164 + 31.1: THE HEADPHONE NEBULA

 2026 May 27

PK 164 +31.1: The Headphone Nebula
Image Credit & Copyright: Bernard Miller
Text: Keighley Rockcliffe (NASA GSFC, UMBC CSST, CRESST II)

Explanation: What is a pair of headphones doing in the sky? Today’s image features the Headphone Nebula, also known as PK 164 +31.1 or Jones-Emberson 1. This planetary nebula, the remnant of a dying Sun-like star, faintly occupies an angular region of the Lynx constellation about 1/5^th the diameter of the full moon. The red and blue-ish green colors trace hydrogen and oxygen atoms, respectively, that have been excited and ionized by the nebula's central white dwarf. The headphone shape, where two lobes of hydrogen puncture the inner region of oxygen, adds this object to a long list of oddly shaped nebulae. The morphology of such strange nebulae hint at the presence of a stellar or planetary companion, which can stir the material flowing out from the dying star. You can listen to Hubble and JWST sonifications of planetary nebulae through your very own headphones!

Astronomy - NGC 3360 AND BURCIN'S GALAXY

 2026 May 26

NGC 3660 and Burçin's Galaxy
Image Credit & Copyright: Adam Block, El Sauce Obs.

Explanation: The upper galaxy might be more photogenic, but the lower galaxy is more unusual. The galaxy up top is NGC 3660, a spiral galaxy similar to our own Milky Way galaxy in that it has several bright blue spiral arms and a central bar of stars, dust, and gas. Captured by chance in the featured deep and colorful image, surprisingly, is SN 2026cff, a supernova found just to the right of the central bar. Farther in the distance is the bottom galaxy, known informally as Burçin’s galaxy, but formally cataloged as LEDA 1000714. The center of this galaxy appears to be an old elliptical galaxy, but it is strangely surrounded by not one but two rings of stars. What created Burçin's galaxy is a mystery and remains a continuing topic of research, but it likely involves the accretion of one or more smaller galaxies.

Astronomy - THACKERAY'S GLOBULES

 2026 May 25

Thackeray's Globules
Image Credit & Copyright: John Hayes

Explanation: What are these strange space globs? Situated in rich star fields and glowing hydrogen gas, these opaque clouds of interstellar dust and gas are so large they might be able to form stars. Their home is known as IC 2944, a bright stellar nursery located about 7,600 light years away toward the constellation of the Centaur (Centaurus). The largest of these dark globules, first spotted by A. D. Thackeray in 1950 using a telescope in South Africa, is likely two separate but overlapping clouds, each more than one light-year wide. Along with other data, the featured Hubble palette image from the El Sauce Observatory in Chile, indicates that Thackeray's globules are fractured and churning as a result of intense ultraviolet radiation from young, hot stars already energizing and heating the bright emission nebula. These and similar dark globules known to be associated with other star forming regions may ultimately be dissipated by their hostile environment -- like cosmic lumps of butter in a hot frying pan.

Vulcanologie - PICO DO FOGO - (CAP-VERT)

Pico do Fogo est plus la grande montagne du Cap-Vert, avec 2829m d'altitude.

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Géoglyphes - LES CELEBRES LIGNES DE NAZCA

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