ASTRONOMY - Earth at night

 2022 February 13

Earth at Night
Image Credit: NASA, Suomi NPP VIIRS; Data: Miguel Román (NASA GSFC); Processing: Joshua Stevens

Explanation: This is what the Earth looks like at night. Can you find your favorite country or city? Surprisingly, city lights make this task quite possible. Human-made lights highlight particularly developed or populated areas of the Earth's surface, including the seaboards of Europe, the eastern United States, and Japan. Many large cities are located near rivers or oceans so that they can exchange goods cheaply by boat. Particularly dark areas include the central parts of South America, Africa, Asia, and Australia. The featured image, nicknamed Black Marble, is actually a composite of hundreds of pictures remade in 2016 from data taken by the orbiting Suomi NPP satellite.

ASTRONOMY - Aurora by Moonlight

 2022 February 12

Aurora by Moonlight
Image Credit & Copyright: P-M Hedén (Clear Skies, TWAN)

Explanation: The ice was singing as light from a bright gibbous Moon cast shadows across this frozen lake, about 20 kilometers north of Stockholm, Sweden, planet Earth. In the alluring night skyscape captured on February 10, shimmering auroral curtains of light dance in the evening sky. On that northern night nature's performance included the auroral displays fostered by a minor geomagnetic storm. Stormy space weather was the result of a coronal mass ejection, erupting from a solar prominence days earlier and brushing our fair planet's magnetosphere.

AERONAUTIQUE - L'Airbus A300-600ST ou l'avion " Beluga"

Il tient son surnom de « Beluga » en raison de la forme de sa carlingue qui évoque immédiatement l'apparence du cétacé du même nom. L'A300-600ST est un avion construit en cinq exemplaires par Airbus. Il sert à l'avionneur pour transporter les pièces volumineuses des appareils entre ses différents sites de production européens.

Le Beluga peut emporter une charge utile de 50 tonnes. Dans sa soute qui mesure 7,4 mètres de diamètre et 37,7 mètres de long, il peut par exemple transporter deux ailes d'Airbus A330 ou un fuselage d'Airbus A320+.

© Laurent ERRERA, CC by-sa 2.0

FuturaSciences

ASTRONOMY - T Tauri and Hind's Variable Nebula

 2022 February 10

T Tauri and Hind's Variable Nebula
Image Credit & Copyright: Dawn Lowry, Gian Lorenzo Ferretti, Ewa Pasiak and Terry Felty

Explanation: The star with an orange tint near top center in this dusty telescopic frame is T Tauri, prototype of the class of T Tauri variable stars. Next to it (right) is a yellow cosmic cloud historically known as Hind's Variable Nebula (NGC 1555). About 650 light-years away, at the boundary of the local bubble and the Taurus molecular cloud, both star and nebula are seen to vary significantly in brightness but not necessarily at the same time, adding to the mystery of the intriguing region. T Tauri stars are now generally recognized as young (less than a few million years old), sun-like stars still in the early stages of formation. To further complicate the picture, infrared observations indicate that T Tauri itself is part of a multiple system and suggest that the associated Hind's Nebula may also contain a very young stellar object. The well-composed image spans about 8 light-years at the estimated distance of T Tauri.

ASTRONOMY - Aurora and Light Pillars over Norway

 2022 February 8

Aurora and Light Pillars over Norway

Image Credit & Copyright: Alexandre Correia

Explanation: Which half of this sky is your favorite? On the left, the night sky is lit up by particles expelled from the Sun that later collided with Earth's upper atmosphere — creating bright auroras. On the right, the night glows with ground lights reflected by millions of tiny ice crystals falling from the sky — creating light pillars. And in the center, the astrophotographer presents your choices. The light pillars are vertical columns because the fluttering ice-crystals are mostly flat to the ground, and their colors are those of the ground lights. The auroras cover the sky and ground in the green hue of glowing oxygen, while their transparency is clear because you can see stars right through them. Distant stars dot the background, including bright stars from the iconic constellation of Orion. The featured image was captured in a single exposure two months ago near Kautokeino, Norway.

ART FRACTAL - Neige

 

L'eau se cristallise en neige par des courbes fractales. 

© Michael, Wikimedia Commons, CC by-sa 2.0

FuturaSciences

ASTRONOMY - NGC 4651: The Umbrella Galaxy

 2022 February 7

NGC 4651: The Umbrella Galaxy
Image Credit & Copyright: CFHT, Coelum, MegaCam, J.-C. Cuillandre (CFHT) & G. A. Anselmi (Coelum)

Explanation: It's raining stars. What appears to be a giant cosmic umbrella is now known to be a tidal stream of stars stripped from a small satellite galaxy. The main galaxy, spiral galaxy NGC 4651, is about the size of our Milky Way, while its stellar parasol appears to extend some 100 thousand light-years above this galaxy's bright disk. A small galaxy was likely torn apart by repeated encounters as it swept back and forth on eccentric orbits through NGC 4651. The remaining stars will surely fall back and become part of a combined larger galaxy over the next few million years. The featured image was captured by the Canada-France-Hawaii Telescope (CFHT) in Hawaii, USA. The Umbrella Galaxy lies about 50 million light-years distant toward the well-groomed northern constellation Coma Berenices.

ASTRONOMY - Blue Marble Earth

 2022 February 6

Blue Marble Earth
Image Credit: NASA, Apollo 17 Crew

Explanation: Welcome to planet Earth, the third planet from a star named the Sun. The Earth is shaped like a sphere and composed mostly of rock. Over 70 percent of the Earth's surface is water. The planet has a relatively thin atmosphere composed mostly of nitrogen and oxygen. The featured picture of Earth, dubbed The Blue Marble, was taken from Apollo 17 in 1972 and features Africa and Antarctica. It is thought to be one of the most widely distributed photographs of any kind. Earth has a single large Moon that is about 1/4 of its diameter and, from the planet's surface, is seen to have almost exactly the same angular size as the Sun. With its abundance of liquid water, Earth supports a large variety of life forms, including potentially intelligent species such as dolphins and humans. Please enjoy your stay on planet Earth.

ASTRONOMY - Symbiotic R Aquarii

 2022 February 5

Symbiotic R Aquarii
Image Credit: X-ray: NASA/CXC/SAO/R. Montez et al.; Optical: Data: NASA/ESA/STScI, Processing: Judy Schmidt (CC BY-NC-SA)

Explanation: Variable star R Aquarii is actually an interacting binary star system, two stars that seem to have a close symbiotic relationship. Centered in this space-based optical/x-ray composite image it lies about 710 light years away. The intriguing system consists of a cool red giant star and hot, dense white dwarf star in mutual orbit around their common center of mass. With binoculars you can watch as R Aquarii steadily changes its brightness over the course of a year or so. The binary system's visible light is dominated by the red giant, itself a Mira-type long period variable star. But material in the cool giant star's extended envelope is pulled by gravity onto the surface of the smaller, denser white dwarf, eventually triggering a thermonuclear explosion, blasting material into space. Astronomers have seen such outbursts over recent decades. Evidence for much older outbursts is seen in these spectacular structures spanning almost a light-year as observed by the Hubble Space Telescope (in red and blue). Data from the Chandra X-ray Observatory (in purple) shows the X-ray glow from shock waves created as a jet from the white dwarf strikes surrounding material.

AERONAUTIQUE - Solar Impulse, l’avion solaire

Solar Impulse est un projet d'avion solaire initié en 2003 par l'aventurier suisse Bertrand Piccard et le pilote André Borschberg, accompagnés par l'École polytechnique fédérale de Lausanne. Ce monoplace dispose d'une envergure de 72 mètres et de quatre moteurs électriques (de 13,5 kW chacun) alimentés par 11.628 cellules photovoltaïques.

© Matth1, GFDL
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