ASTRONOMY - Manicouagan Impact Crater from Space

 2024 May 25

Manicouagan Impact Crater from Space
Image Credit: NASA, International Space Station Expedition 59

Explanation: Orbiting 400 kilometers above Quebec, Canada, planet Earth, the International Space Station Expedition 59 crew captured this snapshot of the broad St. Lawrence River and curiously circular Lake Manicouagan on April 11. Right of center, the ring-shaped lake is a modern reservoir within the eroded remnant of an ancient 100 kilometer diameter impact crater. The ancient crater is very conspicuous from orbit, a visible reminder that Earth is vulnerable to rocks from space. Over 200 million years old, the Manicouagan crater was likely caused by the impact of a rocky body about 5 kilometers in diameter. Currently, there is no known asteroid with a significant probability of impacting Earth in the next century. Each month, NASA’s Planetary Defense Coordination Office releases an update featuring the most recent figures on near-Earth object close approaches, and other facts about comets and asteroids that could pose a potential impact hazard with Earth.

SANTé/MEDECINE - Virus et bactéries mortels - Bacillus anthracis, la bactérie à l'origine de l'anthrax

La maladie du charbon, ou anthrax, est due à une bactérie nommée Bacillus anthracis, ou bacille du charbon. Le plus souvent, celle-ci pénètre dans l'organisme par l'intermédiaire d'une blessure dans la peau. Le corps parvient alors à s'en débarrasser tout seul.

En revanche, lorsque les spores de la bactérie sont avalées ou respirées, c'est une tout autre histoire. Par voies aériennes, elle n'est pas loin d'être mortelle dans 100 % des cas. C'est pour cela qu'elle inspire autant les bioterroristes.

© Janice Haney Carr, CDC

ASTRONOMY - M78 from the Euclid Space Telescope

 2024 May 24

M78 from the Euclid Space Telescope
Image Credit & License: ESA, Euclid, Euclid Consortium, NASA; Processing: J.-C. Cuillandre (CEA Paris-Saclay), G. Anselmi

Explanation: Star formation can be messy. To help find out just how messy, ESA's new Sun-orbiting Euclid telescope recently captured the most detailed image ever of the bright star forming region M78. Near the image center, M78 lies at a distance of only about 1,300 light-years away and has a main glowing core that spans about 5 light-years. The featured image was taken in both visible and infrared light. The purple tint in M78's center is caused by dark dust preferentially reflecting the blue light of hot, young stars. Complex dust lanes and filaments can be traced through this gorgeous and revealing skyscape. On the upper left is associated star forming region NGC 2071, while a third region of star formation is visible on the lower right. These nebulas are all part of the vast Orion Molecular Cloud Complex which can be found with even a small telescope just north of Orion's belt.

NUCLEAIRE - Comment survivre à une explosion nucléaire ? Trouvez un abri

Irwin Redlener conseille de chercher un abri dans la direction opposée aux bâtiments en ruine et dans la direction opposée au vent. Si vous ne vous trouvez pas à proximité d'un abri connu, essayez de vous éloigner le plus possible de l'explosion dans les 10 à 15 minutes qui suivent, puis mettez-vous immédiatement à l'abri pour éviter le nuage de radiations qui redescend.

©Shutterstock

NUCLEAIRE - Comment survivre à une explosion nucléaire ? L'exposition aux radiations

Selon le Johns Hopkins Center for Health Security, le risque d'exposition aux radiations diminue de 55 % une heure après une explosion et de 80 % après 24 heures.

©Shutterstock

ASTRONOMY - Unraveling NGC 3169

 2024 May 23

Unraveling NGC 3169
Image Credit & Copyright: Christophe Vergnes, Aziz Kaeouach

Explanation: Spiral galaxy NGC 3169 looks to be unraveling like a ball of cosmic yarn. It lies some 70 million light-years away, south of bright star Regulus toward the faint constellation Sextans. Wound up spiral arms are pulled out into sweeping tidal tails as NGC 3169 (left) and neighboring NGC 3166 interact gravitationally. Eventually the galaxies will merge into one, a common fate even for bright galaxies in the local universe. Drawn out stellar arcs and plumes are clear indications of the ongoing gravitational interactions across the deep and colorful galaxy group photo. The telescopic frame spans about 20 arc minutes or about 400,000 light-years at the group's estimated distance, and includes smaller, bluish NGC 3165 to the right. NGC 3169 is also known to shine across the spectrum from radio to X-rays, harboring an active galactic nucleus that is the site of a supermassive black hole.

NUCLEAIRE - Comment survivre à une explosion nucléaire ? 15 minutes avant les retombées des radiations nucléaires

Les survivants d'une attaque nucléaire disposeraient d'environ 15 minutes avant que les retombées nucléaires n'atteignent le sol. L'exposition à ces particules peut entraîner un empoisonnement aux radiations, qui peut endommager les cellules du corps et être potentiellement mortel.

©Shutterstock

ASTRONOMY - Green Aurora over Sweden

 2024 May 22

Green Aurora over Sweden
Image Credit & Copyright: Göran Strand

Explanation: It was bright and green and stretched across the sky. This striking aurora display was captured in 2016 just outside of Östersund, Sweden. Six photographic fields were merged to create the featured panorama spanning almost 180 degrees. Particularly striking aspects of this aurora include its sweeping arc-like shape and its stark definition. Lake Storsjön is seen in the foreground, while several familiar constellations and the star Polaris are visible through the aurora, far in the background. Coincidently, the aurora appears to avoid the Moon visible on the lower left. The aurora appeared a day after a large hole opened in the Sun's corona, allowing particularly energetic particles to flow out into the Solar System. The green color of the aurora is caused by oxygen atoms recombining with ambient electrons high in the Earth's atmosphere.

ASTRONOMY - CG4: The Globule and the Galaxy

 2024 May 21

CG4: The Globule and the Galaxy
Image Credit: CTIO, NOIRLab, DOE, NSF, AURA; Processing: T. A. Rector (U. Alaska Anchorage/NSF’s NOIRLab), D. de Martin & M. Zamani (NSF’s NOIRLab)

Explanation: Can a gas cloud eat a galaxy? It's not even close. The "claw" of this odd looking "creature" in the featured photo is a gas cloud known as a cometary globule. This globule, however, has ruptured. Cometary globules are typically characterized by dusty heads and elongated tails. These features cause cometary globules to have visual similarities to comets, but in reality they are very much different. Globules are frequently the birthplaces of stars, and many show very young stars in their heads. The reason for the rupture in the head of this object is not yet known. The galaxy to the left of the globule is huge, very far in the distance, and only placed near CG4 by chance superposition.

NUCLEAIRE - Comment survivre à une explosion nucléaire ? Si vous êtes en voiture

Si vous êtes dans un véhicule lorsqu'une explosion se produit, arrêtez-vous en toute sécurité et mettez-vous à l'abri dans le véhicule. Il est toutefois important de ne pas y rester trop longtemps.

©Shutterstock