ASTRONOMY - Jupiter's Swirls from Juno

 2023 May 23

Jupiter's Swirls from Juno
Image Credit: NASA/JPL-Caltech/SwRI/MSSS; Processing & License: Kevin M. Gill

Explanation: Big storms are different on Jupiter. On Earth, huge hurricanes and colossal cyclones are centered on regions of low pressure, but on Jupiter, it is the high-pressure, anti-cyclone storms that are the largest. On Earth, large storms can last weeks, but on Jupiter they can last years. On Earth, large storms can be as large as a country, but on Jupiter, large storms can be as large as planet Earth. Both types of storms are known to exhibit lightning. The featured image of Jupiter's clouds was composed from images and data captured by the robotic Juno spacecraft as it swooped close to the massive planet in August 2020.  A swirling white oval is visible nearby, while numerous smaller cloud swirls extend into the distance.  On Jupiter, light-colored clouds are usually higher up than dark clouds. Despite their differences, studying storm clouds on distant Jupiter provides insights into storms and other weather patterns on

ASTRONOMY - Galileo's Europa

 2023 May 20

Galileo's Europa
Image Credit: NASA, JPL-Caltech, SETI Institute, Cynthia Phillips, Marty Valenti

Explanation: Looping through the Jovian system in the late 1990s, the Galileo spacecraft recorded stunning views of Europa and uncovered evidence that the moon's icy surface likely hides a deep, global ocean. Galileo's Europa image data has been remastered here, with improved calibrations to produce a color image approximating what the human eye might see. Europa's long curving fractures hint at the subsurface liquid water. The tidal flexing the large moon experiences in its elliptical orbit around Jupiter supplies the energy to keep the ocean liquid. But more tantalizing is the possibility that even in the absence of sunlight that process could also supply the energy to support life, making Europa one of the best places to look for life beyond Earth. What kind of life could thrive in a deep, dark, subsurface ocean? Consider planet Earth's own extreme shrimp.

ASTRONOMY - Sunspot with Light Bridge

 2023 May 17

Sunspot with Light Bridge
Image Credit & Copyright: Mark Johnston

Explanation: Why would a small part of the Sun appear slightly dark? Visible is a close-up picture of sunspots, depressions on the Sun's surface that are slightly cooler and less bright than the rest of the Sun. The Sun's complex magnetic field creates these cool regions by inhibiting hot material from entering the spots. Sunspots can be larger than the Earth and typically last for about a week. Part of active region AR 3297 crossing the Sun in early May, the large lower sunspot is spanned by an impressive light bridge of hot and suspended solar gas. This high-resolution picture also shows clearly that the Sun's surface is a bubbling carpet of separate cells of hot gas. These cells are known as granules. A solar granule is about 1000 kilometers across and lasts for only about 15 minutes.

ASTRONOMY - Total Eclipse: The Big Corona

 2023 May 16

Total Eclipse: The Big Corona
Image Credit & Copyright: Reinhold Wittich

Explanation: Most photographs don't adequately portray the magnificence of the Sun's corona. Seeing the corona first-hand during a total solar eclipse is unparalleled. The human eye can adapt to see coronal features and extent that average cameras usually cannot. Welcome, however, to the digital age. The featured image digitally combined short and long exposures taken in Exmouth, Australia that were processed to highlight faint and extended features in the corona during the total solar eclipse that occurred in April of 2023. Clearly visible are intricate layers and glowing caustics of an ever changing mixture of hot gas and magnetic fields in the Sun's corona. Looping prominences appear bright pink just past the Sun's edge. Images taken seconds before and after the total eclipse show glimpses of the background Sun known as Baily's Beads and diamond ring effect. The next total solar eclipse will cross North America in April of 2024.

ASTRONOMY - M16: Eagle Nebula Deep Field

 023 May 15

M16: Eagle Nebula Deep Field
Image Credit & Copyright: Gianni Lacroce

Explanation: From afar, the whole thing looks like an eagle. A closer look at the Eagle Nebula, however, shows the bright region is actually a window into the center of a larger dark shell of dust. Through this window, a brightly-lit workshop appears where a whole open cluster of stars is being formed. In this cavity, tall pillars and round globules of dark dust and cold molecular gas remain where stars are still forming. Already visible are several young bright blue stars whose light and winds are burning away and pushing back the remaining filaments and walls of gas and dust. The Eagle emission nebula, tagged M16, lies about 6500 light years away, spans about 20 light-years, and is visible with binoculars toward the constellation of the Serpent (Serpens). This picture involved long and deep exposures and combined three specific emitted colors emitted by sulfur (colored as yellow), hydrogen (red), and oxygen (blue).

ART FRACTAL - Fractale symétrique aux allures de flocon de neige

Cette fractale associe le rouge, le rose, le blanc et le vert. Sa structure symétrique évoque celle d'un flocon de neige. 

© Futura

AERONAUTIQUE - Avions de légende - Le Fokker Dr.I - l’avion du Baron Rouge

Le Fokker Dr.I (ou Dreidecker, qui signifie « triplan » en allemand) est un avion de chasse allemand qui s'est illustré lors de la première guerre mondiale. Sa structure à trois ailes courtes superposées lui assurait une excellente maniabilité, notamment pour les virages serrés. L'avion a gagné ses lettres de noblesse aux mains de Manfred von Richthofen. Auteur de 80 combats victorieux, il fut surnommé le « Baron Rouge » en raison de la couleur de son appareil.

© Julian Herzog, CC by 3.0

GEMMOLOGIE - La pyrite - L'or des fous

Ce sulfure de fer est susceptible de cristalliser. Il prend alors des reflets dorés. Durant la ruée vers l'or, la pyrite a d'ailleurs été confondue par de nombreux mineurs avec le précieux métal à cause de son éclat et de sa couleur. Cet épisode lui a valu le surnom d' « or des fous ». Couleurs : doré pâle. 

© DidierDescouens, Wikimedia Commons, CC by-sa 3.0

ASTRONOMY - To Fly Free in Space

 2023 May 14

To Fly Free in Space
Image Credit: NASA, STS-41B

Explanation: What would it be like to fly free in space? At about 100 meters from the cargo bay of the space shuttle Challenger, Bruce McCandless II was living the dream -- floating farther out than anyone had ever been before. Guided by a Manned Maneuvering Unit (MMU), astronaut McCandless, pictured, was floating free in space. During Space Shuttle mission 41-B in 1984, McCandless and fellow NASA astronaut Robert Stewart were the first to experience such an "untethered space walk". The MMU worked by shooting jets of nitrogen and was used to help deploy and retrieve satellites. With a mass over 140 kilograms, an MMU is heavy on Earth, but, like everything, is weightless when drifting in orbit. The MMU was later replaced with the SAFER backpack propulsion unit.

ASTRONOMY - Apollo 17: The Crescent Earth

 2023 May 13

Apollo 17: The Crescent Earth
Image Credit: Apollo 17, NASA; Restoration - Toby Ord

Explanation: Our fair planet sports a curved, sunlit crescent against the black backdrop of space in this stunning photograph. From the unfamiliar perspective, the Earth is small and, like a telescopic image of a distant planet, the entire horizon is completely within the field of view. Enjoyed by crews on board the International Space Station, only much closer views of the planet are possible from low Earth orbit. Orbiting the planet once every 90 minutes, a spectacle of clouds, oceans, and continents scrolls beneath them with the partial arc of the planet's edge in the distance. But this digitally restored image presents a view so far only achieved by 24 humans, Apollo astronauts who traveled to the Moon and back again between 1968 and 1972. The original photograph, AS17-152-23420, was taken by the homeward bound crew of Apollo 17, on December 17, 1972. For now it is the last picture of Earth from this planetary perspective taken by human hands.