ASTRONOMY - Meteor and Milky Way over the Alps

 2023 July 16

Meteor and Milky Way over the Alps
Image Credit & Copyright: Nicholas Roemmelt (Venture Photography)

Explanation: Now this was a view with a thrill. From Mount Tschirgant in the Alps, you can see not only nearby towns and distant Tyrolean peaks, but also, weather permitting, stars, nebulas, and the band of the Milky Way Galaxy. What made the arduous climb worthwhile this night, though, was another peak -- the peak of the 2018 Perseids Meteor Shower. As hoped, dispersing clouds allowed a picturesque sky-gazing session that included many faint meteors, all while a carefully positioned camera took a series of exposures. Suddenly, a thrilling meteor -- bright and colorful -- slashed down right next to the nearly vertical band of the Milky Way. As luck would have it, the camera caught it too. Therefore, a new image in the series was quickly taken with one of the sky-gazers posing on the nearby peak. Later, all of the images were digitally combined.

ASTRONOMY - Webb's Rho Ophiuchi

 2023 July 13

Webb's Rho Ophiuchi
Image Credit: NASA, ESA, CSA, STScI, Klaus Pontoppidan (STScI), Processing: Alyssa Pagan (STScI)

Explanation: A mere 390 light-years away, Sun-like stars and future planetary systems are forming in the Rho Ophiuchi molecular cloud complex, the closest star-forming region to our fair planet. The James Webb Space Telescope's NIRCam peered into the nearby natal chaos to capture this infrared image at an inspiring scale. The spectacular cosmic snapshot was released to celebrate the successful first year of Webb's exploration of the Universe. The frame spans less than a light-year across the Rho Ophiuchi region and contains about 50 young stars. Brighter stars clearly sport Webb's characteristic pattern of diffraction spikes. Huge jets of shocked molecular hydrogen blasting from newborn stars are red in the image, with the large, yellowish dusty cavity carved out by the energetic young star near its center. Near some stars in the stunning image are shadows cast by their protoplanetary disks.

ASTRONOMY - Stars, Dust and Nebula in NGC 6559

 2023 July 10

Stars, Dust and Nebula in NGC 6559
Image Credit & Copyright: Adam Block, Telescope Live

Explanation: When stars form, pandemonium reigns. A textbook case is the star forming region NGC 6559. Visible in the featured image are red glowing emission nebulas of hydrogen, blue reflection nebulas of dust, dark absorption nebulas of dust, and the stars that formed from them. The first massive stars formed from the dense gas will emit energetic light and winds that erode, fragment, and sculpt their birthplace. And then they explode. The resulting morass can be as beautiful as it is complex. After tens of millions of years, the dust boils away, the gas gets swept away, and all that is left is a bare open cluster of stars.

METEOROLOGIE - Phénomène extraordinaire : le nuage en forme de champignon atomique

Avez-vous déjà eu l'impression qu'une explosion nucléaire était en train de se produire dans le ciel ? Lors de plus fortes dégradations orageuses, il arrive parfois qu'un nuage en forme de champignon atomique surgisse dans le ciel.

Il s'agit d'un type particulier de nuage d'orage, le Cumulonimbus capillatus incus. Le cumulonimbus est en fait un terme général qui désigne tout nuage d'orage, mais il en existe plusieurs espèces avec des conséquences différentes. Les orages les plus impressionnants en forme de champignon atomique font souvent la Une des actualités des médias locaux. Il arrive même qu'ils créent des moments de panique parmi la population, tant leur forme peut être inquiétante.

Qu'est ce qui donne à un simple cumulonimbus une allure aussi apocalyptique ? C'est en réalité l'enclume très étendue qui donne cette impression de catastrophe nucléaire. L'enclume (incus en latin) est le sommet du nuage d'orage, qui s'étire horizontalement sur 20 à 50 kilomètres lorsqu'il arrive au niveau de la tropopause. Le nuage ne peut plus continuer de monter en altitude, son sommet s'écrase alors contre la tropopause et forme une sorte de couvercle.

FuturaSciences

ASTRONOMY - Doomed Star Eta Carinae

 2023 July 9

Doomed Star Eta Carinae
Image Credit & Copyright: NASA, ESA, Hubble; Processing & License: Judy Schmidt

Explanation: Eta Carinae may be about to explode. But no one knows when - it may be next year, it may be one million years from now. Eta Carinae's mass - about 100 times greater than our Sun - makes it an excellent candidate for a full blown supernova. Historical records do show that about 170 years ago Eta Carinae underwent an unusual outburst that made it one of the brightest stars in the southern sky. Eta Carinae, in the Keyhole Nebula, is the only star currently thought to emit natural LASER light. This featured image brings out details in the unusual nebula that surrounds this rogue star. Diffraction spikes, caused by the telescope, are visible as bright multi-colored streaks emanating from Eta Carinae's center. Two distinct lobes of the Homunculus Nebula encompass the hot central region, while some strange radial streaks are visible in red extending toward the image right. The lobes are filled with lanes of gas and dust which absorb the blue and ultraviolet light emitted near the center. The streaks, however, remain unexplained.

ASTRONOMY - Fireworks vs Supermoon

 2023 July 6

Fireworks vs Supermoon
Image Credit & Copyright: Michael Seeley

Explanation: On July 4, an almost Full Moon rose in planet Earth's evening skies. Also known as a Buck Moon, the full lunar phase (full on July 3 at 11:39 UTC) was near perigee, the closest point in the Moon's almost monthly orbit around planet Earth. That qualified this July's Full Moon as a supermoon, the first of four supermoons in 2023. Seen from Cocoa Beach along Florida's Space Coast on July 4, any big, bright, beautiful Full Moon would still have to compete for attention though. July's super-moonrise was captured here against a super-colorful fireworks display.

PHOTOGRAPHIE - Le monde explosif d'Alan Sailer - Au ralenti : explosion d'un litchi

Un litchi qui explose sous l'impact d'une balle de plomb très rapide qui se déplace à environ 200 mètres par seconde. Tirée à partir d'un fusil à plomb, la balle a une énergie totale d'environ 10 joules.

© Alan Sailer

ASTRONOMY - A Map of the Observable Universe

 2023 July 5

A Map of the Observable Universe
Image Credit & Copyright: B. Ménard & N. Shtarkman; Data: SDSS, Planck, JHU, Sloan, NASA, ESA

Explanation: What if you could see out to the edge of the observable universe? You would see galaxies, galaxies, galaxies, and then, well, quasars, which are the bright centers of distant galaxies. To expand understanding of the very largest scales that humanity can see, a map of the galaxies and quasars found by the Sloan Digital Sky Survey from 2000 to 2020 -- out to near the edge of the observable universe -- has been composed. Featured here, one wedge from this survey encompasses about 200,000 galaxies and quasars out beyond a look-back time of 12 billion years and cosmological redshift 5. Almost every dot in the nearby lower part of the illustration represents a galaxy, with redness indicating increasing redshift and distance. Similarly, almost every dot on the upper part represents a distant quasar, with blue-shaded dots being closer than red. Clearly shown among many discoveries, gravity between galaxies has caused the nearby universe to condense and become increasingly more filamentary than the distant universe.

ASTRONOMY - Aurora over Icelandic Waterfall

 2023 July 4

Aurora over Icelandic Waterfall
Image Credit & Copyright: Cari Letelier

Explanation: It seemed like the sky exploded. The original idea was to photograph an aurora over a waterfall. After waiting for hours under opaque clouds, though, hope was running out. Others left. Then, unexpectedly, the clouds moved away. Suddenly, particles from a large solar magnetic storm were visible impacting the Earth's upper atmosphere with full effect. The night sky filled with colors and motion in a thrilling auroral display. Struggling to steady the camera from high Earthly winds, the 34 exposures that compose the featured image were taken. The resulting featured composite image shows the photogenic Godafoss (Goðafoss) waterfall in northern Iceland in front of a very active aurora in late February. The solar surface explosion that expelled the energetic particles occurred a few days before. Our Sun is showing an impressive amount of surface activity as it approaches solar maximum, indicating that more impressive auroras are likely to appear in Earth's northern and southern sky over the next few years.

PHOTOGRAPHIE - Le monde explosif d'Alain Sailer - Explosion d'une crème glacée au ralenti

Cette délicieuse crème glacée garnie de noix est frappée par une petite bille d'un roulement à bille en acier. La bille a été propulsée par un canon à air haute pression (10 bars). L'énergie totale de la bille d'acier est d'environ 100 joules. 

© Alan Sailer