ASTRONOMY - Rosette Nebula Deep Field

 2025 June 17

Rosette Nebula Deep Field
Image Credit: Toni Fabiani Méndez

Explanation: Can you find the Rosette Nebula? The red flowery-looking nebula just above the image center may seem a good choice, but that's not it. The famous Rosette Nebula is really located on the lower right, here colored blue and white, and connected to the other nebulas by gold-colored filaments. Because the featured image of Rosette's field is so wide, and because of its deep red exposure, it seems to contain other flowers. Designated NGC 2237, the center of the Rosette Nebula is populated by the bright blue stars of open cluster NGC 2244, whose winds and energetic light are evacuating the nebula's center. The Rosette Nebula is about 5,000 light years distant and, just by itself, spans about three times the diameter of a full moon. This flowery field can be found toward the constellation of the Unicorn (Monoceros).

SANTé/MEDECINE - Procédé révolutionnaire dans la lutte contre le cancer - 1/6 : Introduction

Imaginez un monde où le cancer pourrait être traité sans les effets secondaires dévastateurs des médicaments ou des radiations. Ce rêve est en train de devenir réalité ! Des scientifiques viennent de franchir une étape majeure : ils ont découvert une méthode pour briser les cellules cancéreuses en utilisant simplement la lumière. Cette avancée promet de transformer la médecine et d’offrir de l’espoir à des millions de personnes.

©Adobe Stock

LA TERRE VUE DU CIEL - Le mont Elgon en Afrique

Le mont Elgon est un stratovolcan culminant à 4.321 mètres d'altitude, sur la frontière entre le Kenya et l'Ouganda, en Afrique.

© Nasa

ASTRONOMY - Two Worlds, One Sun

 2025 June 15

Two Worlds, One Sun
Left Image Credit & Copyright: Damia Bouic;
Right Image Credit: NASA, JPL-Caltech, MSSS; Digital processing: Damia Bouic

Explanation: How different does sunset appear from Mars than from Earth? For comparison, two images of our common star were taken at sunset, one from Earth and one from Mars. These images were scaled to have the same angular width and are featured here side-by-side. A quick inspection will reveal that the Sun appears slightly smaller from Mars than from Earth. This makes sense since Mars is 50% further from the Sun than Earth. More striking, perhaps, is that the Martian sunset is noticeably bluer near the Sun than the typically orange colors near the setting Sun from Earth. The reason for the blue hues from Mars is not fully understood, but thought to be related to forward scattering properties of Martian dust. The terrestrial sunset was taken in 2012 March from Marseille, France, while the Martian sunset was captured in 2015 by NASA's robotic Curiosity rover from Gale crater on Mars.

ASTRONOMIE - Iréelle

La pleine lune se lève sur l’ancien temple grec de Poséidon au bord du cap Sounion. 

Louisa Gouliamaki / REUTERS

ASTRONOMY - Meteors and Satellite Trails over the Limay River

 2025 June 14

Meteors and Satellite Trails over the Limay River
Image Credit & Copyright: Martín Moliné

Explanation: What are all those streaks in the sky? A galaxy, many satellite trails, and a few meteors. First, far in the distance, the majestic band of our Milky Way Galaxy runs down the left. Mirroring it on the right are several parallel trails of Earth-orbiting Starlink satellites. Many fainter satellite trails also crisscross the image. The two short and bright streaks are meteors — likely members of the annual Eta Aquariids meteor shower. The planet Venus shines on the lower right. Venus and the satellites shine by reflected sunlight. The featured picture is a composite of exposures all taken in a few hours on May 4 over the Limay River in Argentina.

METEOROLOGIE - Le jour où des grêlons d’1 kg sont tombés : 92 victimes

La majorité des grêlons qui tombent sous les orages et les averses ne pèsent que quelques grammes. Mais il y a quelques années, c'est un grêlon d'un kilogramme qui a été retrouvé, et homologué.

Dans les situations orageuses les plus violentes, sous les supercellules par exemple, il arrive que des grêlons pesant plusieurs centaines de grammes tombent. Lorsqu'un grêlon mesure plus de 5 centimètres, il peut alors peser jusqu'à 500 grammes. Mais dans les cas les plus extrêmes, des grêlons de 800 à 900 grammes, avec un diamètre de 15 centimètres ou plus, sont possibles.

Ces grêlons géants sont rares d'une manière générale, et ils tombent le plus souvent aux États-Unis, en Argentine, au Brésil, au Chili, ou encore dans certains États d'Afrique, comme en République du Congo.

Cependant, le record mondial, homologué par l'Organisation météorologique mondiale, a été enregistré au Bangladesh : le 14 avril 1986, un grêlon pesant 1,02 kg a été ramassé. Ce jour-là, l'orage de grêle a été catastrophique : les grêlons géants ont causé la mort de 92 personnes, et ravagé les cultures de la ville Gopalganj, au sud du pays. L'événement paraît extraordinaire, mais il est tout à fait probable : le Bangladesh subit une météo très agitée, et les orages ultra-violents sont courants.

FuturaSciences

ASTRONOMY - Rubin's Galaxy

 2025 June 13

Rubin's Galaxy
Image Credit: NASA, ESA, B. Holwerda (University of Louisville)

Explanation: In this Hubble Space Telescope image the bright, spiky stars lie in the foreground toward the heroic northern constellation Perseus and well within our own Milky Way galaxy. In sharp focus beyond is UGC 2885, a giant spiral galaxy about 232 million light-years distant. Some 800,000 light-years across compared to the Milky Way's diameter of 100,000 light-years or so, it has around 1 trillion stars. That's about 10 times as many stars as the Milky Way. Part of an investigation to understand how galaxies can grow to such enormous sizes, UGC 2885 was also part of An Interesting Voyage and American astronomer Vera Rubin's pioneering study of the rotation of spiral galaxies. Her work was the first to convincingly demonstrate the dominating presence of dark matter in our universe. A new U.S. coin has been issued to honor Vera Rubin, while the Vera C. Rubin Observatory is scheduled to unveil images from its first look at the cosmos on June 23.

ASTRONOMY - 25 Brightest Stars in the Night Sky

2025 June 11

25 Brightest Stars in the Night Sky
Image Credit & Copyright: Tragoolchitr Jittasaiyapan

Explanation: Do you know the names of some of the brightest stars? It's likely that you do, even though some bright stars have names so old they date back to near the beginning of written language. Many world cultures have their own names for the brightest stars, and it is culturally and historically important to remember them. In the interest of clear global communication, however, the International Astronomical Union (IAU) has begun to designate standardized star names. Featured here in true color are the 25 brightest stars in the night sky, currently as seen by humans, coupled with their IAU-recognized names. Some star names have interesting meanings, including Sirius ("the scorcher" in Latin), Vega ("falling" in Arabic), and Antares ("rival to Mars" in Greek). You are likely even familiar with the name of at least one star too dim to make this list: Polaris. 

ASTRONOMY - Enceladus in True Color

 2025 June 10

Enceladus in True Color
Image Credit: NASA, ESA, JPL, SSI, Cassini Imaging Team

Explanation: Do oceans under the ice of Saturn's moon Enceladus contain life? A reason to think so involves long features -- some dubbed tiger stripes -- that are known to be spewing ice from the moon's icy interior into space. These surface cracks create clouds of fine ice particles over the moon's South Pole and create Saturn's mysterious E-ring. Evidence for this has come from the robot Cassini spacecraft that orbited Saturn from 2004 to 2017. Pictured here, a high resolution image of Enceladus is shown in true color from a close flyby. The deep crevasses are partly shadowed. Why Enceladus is active remains a mystery, as the neighboring moon Mimas, approximately the same size, appears quite dead. An analysis of ejected ice grains has yielded evidence that complex organic molecules exist inside Enceladus. These large carbon-rich molecules bolster -- but do not prove -- that oceans under Enceladus' surface could contain life.