ASTRONOMY - A Whale of an Aurora over Swedish Forest

 2022 March 22

A Whale of an Aurora over Swedish Forest
Image Credit & Copyright: Göran Strand

Explanation: What's that in the sky? An aurora. A large coronal mass ejection occurred on our Sun earlier this month, throwing a cloud of fast-moving electrons, protons, and ions toward the Earth. Part of this cloud impacted our Earth's magnetosphere and, bolstered by a sudden gap, resulted in spectacular auroras being seen at some high northern latitudes. Featured here is a particularly photogenic auroral corona captured above a forest in Sweden from a scenic perch overlooking the city of Östersund. To some, this shimmering green glow of recombining atmospheric oxygen might appear like a large whale, but feel free to share what it looks like to you. The unusually quiet Sun of the past few years has now passed. As our Sun now approaches a solar maximum in its 11-year solar magnetic cycle, dramatic auroras like this are sure to continue.

ASTRONOMY - A Picturesque Equinox Sunset

 2022 March 21

A Picturesque Equinox Sunset
Image Credit & Copyright: Roland Christen

Explanation: What's that at the end of the road? The Sun. Many towns have roads that run east - west, and on two days each year, the Sun rises and sets right down the middle. Today is one of those days: an equinox. Not only is today a day of equal night ("aequus"-"nox") and day time, but also a day when the sun rises precisely to the east and sets due west. Featured here is a picturesque road in northwest Illinois, USA that runs approximately east -west. The image was taken during the March Equinox of 2015, and shows the Sun down the road at sunset. In many cultures, this March equinox is taken to be the first day of a season, typically spring in Earth's northern hemisphere, and autumn in the south. Does your favorite street run east - west? Tonight, at sunset, you can find out with a quick glance.

MUSIC- Karl Bohm - The fountain

"The fountain"

ASTRONOMY - When Rainbows Smile

 2022 March 19

When Rainbows Smile
Image Credit & Copyright: Marcella Giulia Pace

Explanation: Want to see a rainbow smile? Look near the zenith (straight up) when the sun is low in the sky and you might. This example of an ice halo known as a circumzenithal arc was captured above a palm tree top from Ragusa, Sicily on February 24. The vividly colorful arcs are often called smiling rainbows because of their upside down curvature and colors. For circumzenithal arcs the zenith is at the center and red is on the outside, compared to rainbows whose arcs bend toward the horizon after a downpour. True rainbows are formed by water droplets refracting the sunlight to produce a spectrum of colors, though. Circumzenithal arcs are the product of refraction and reflection in flat hexagonal ice crystals, like the ice crystals that create sundogs, formed in high thin clouds.

ASTRONOMY - A Filament in Monoceros

 2022 March 18

A Filament in Monoceros
Image Credit & Copyright: Giorgio Ferrari

Explanation: Bluish reflection nebulae seem to fill this dusty expanse. The sharp telescopic frame spans over 1 degree on the sky toward the faint but fanciful constellation Monoceros, the Unicorn. Seen within the Monoceros R1 cloud complex some 2,500 light-years away, bluish IC 447 is on the left, joined by a long dark filament of dust to IC 446 at lower right. Embedded in IC 447 are young, massive blue stars much hotter than the Sun, whose light is reflected by the cosmic cloud of star stuff. Observations reveal that IC 446 also contains a young stellar object, a massive star still in an early stage of evolution. The dark filament of dust and molecular gas joining the two star-forming regions is over 15 light-years long.

ASTRONOMY - Point Reyes Milky Way

 2022 March 17

Point Reyes Milky Way
Image Credit & Copyright: Dan Zafra

Explanation: Northern winter constellations and a long arc of the Milky Way are setting in this night skyscape looking toward the Pacific Ocean from Point Reyes on planet Earth's California coast. Sirius, alpha star of Canis Major, is prominent below the starry arc toward the left. Orion's yellowish Betelgeuse, Aldebaran in Taurus, and the blue tinted Pleiades star cluster also find themselves between Milky Way and northwestern horizon near the center of the scene. The nebulae visible in the series of exposures used to construct this panoramic view were captured in early March, but are just too faint to be seen with the unaided eye. On that northern night their expansive glow includes the reddish semi-circle of Barnard's Loop in Orion and NGC 1499 above and right of the Pleiades, also known as the California Nebula.

MICROPHOTOGRAPHY - Marek Mis - Micrasterias americana

The photographs presents very common desmid species Micrasterias americana in polarized light. This Micrasterias was situated next to cover slip edge and the entire image, especially the colors and shapes. It was taken using polarized light with two retarders to obtain desired colors and atmosphere.

SmallWorld

ASTRONOMY - The observable Universe

 2022 March 16

The Observable Universe
Illustration Credit & Licence: Wikipedia, Pablo Carlos Budassi

Explanation: How far can you see? Everything you can see, and everything you could possibly see, right now, assuming your eyes could detect all types of radiations around you -- is the observable universe. In light, the farthest we can see comes from the cosmic microwave background, a time 13.8 billion years ago when the universe was opaque like thick fog. Some neutrinos and gravitational waves that surround us come from even farther out, but humanity does not yet have the technology to detect them. The featured image illustrates the observable universe on an increasingly compact scale, with the Earth and Sun at the center surrounded by our Solar System, nearby stars, nearby galaxies, distant galaxies, filaments of early matter, and the cosmic microwave background. Cosmologists typically assume that our observable universe is just the nearby part of a greater entity known as "the universe" where the same physics applies. However, there are several lines of popular but speculative reasoning that assert that even our universe is part of a greater multiverse where either different physical constants occur, different physical laws apply, higher dimensions operate, or slightly different-by-chance versions of our standard universe exist.

ASTRONOMY - A Road to the Stars

 2022 March 15

A Road to the Stars
Image Credit: ESO, Petr Horálek (ESO Photo Ambassador, Inst. of Physics in Opava)

Explanation: Pictured -- a very scenic road to the stars. The road approaches La Silla Observatory in Chile, with the ESO's 3.6-meter telescope just up ahead. To the left are some futuristic-looking support structures for the planned BlackGEM telescopes, an array of optical telescopes that will help locate optical counterparts to gravitational waves detections by LIGO and other detectors. But there is much more. Red airglow illuminates the night sky on the right, while the central band of our Milky Way Galaxy slants across the image center. Jupiter can be seen just above the band near the image center, while Saturn is visible just above the 3.6-meter telescope dome. The two largest satellite galaxies of our Milky Way Galaxy, the LMC and SMC, are seen on the far right. The featured image panorama was built up from multiple 15-second exposures that were captured on 2019 June 30. Two days later, La Silla experienced a rare total eclipse of the Sun.

ART FRACTAL - Définition

Art et fractales : découverte d’un monde infini

 

Rapide définition de ce qu’est une fractale :

Venant du latin « fractus » (brisé ou irrégulier), une figure fractale est un objet géométrique pouvant s’apparenter à une poupée russe à l’infini. Autrement dit, qu’importe l’endroit où l’on zoome et le niveau de ce rapprochement, on pourra observer le même motif. La forme se reproduit à des échelles différentes, sans fin.

Évidemment, « à l’infini » n’est pas toujours possible, mais l’idée est là. On retrouve ce principe dans la nature ; un exemple assez parlant est le chou romanesco :

Le chou romanesco : une fractale naturelle

On observe bien la répétition du motif d’un splendide vert clair : les excroissances sont formées d’ensembles similaires plus petits, et ainsi de suite. Ce n’est évidemment pas le seul exemple naturel : les poumons et leurs alvéoles peuvent aussi être considérés fractales.

Lartboratoire