ASTRONOMY - NGC 2440: Cocoon of a New White Dwarf

 2023 December 24

NGC 2440: Cocoon of a New White Dwarf
Image Credit: NASA, ESA, Hubble; Processing: H. Bond (STScI), R. Ciardullo (PSU), Forrest Hamilton (STScI)

Explanation: What's that in the center? Like a butterfly, a white dwarf star begins its life by casting off a cocoon of gas that enclosed its former self. In this analogy, however, the Sun would be a caterpillar and the ejected shell of gas would become the prettiest cocoon of all. In the featured cocoon, the planetary nebula designated NGC 2440 contains one of the hottest white dwarf stars known. The white dwarf can be seen as the bright orange dot near the image center. Our Sun will eventually become a white dwarf butterfly, but not for another 5 billion years.

ASTRONOMY - A December Summer Night

 2023 December 23

A December Summer Night
Image Credit & Copyright: Ian Griffin (Otago Museum)

Explanation: Colours of a serene evening sky are captured in this 8 minute exposure, made near this December's solstice from New Zealand, southern hemisphere, planet Earth. Looking south, star trails form the short concentric arcs around the rotating planet's south celestial pole positioned just off the top of the frame. At top and left of center are trails of the Southern Cross stars and a dark smudge from the Milky Way's Coalsack Nebula. Alpha and Beta Centauri make the brighter yellow and blue tinted trails, reflected below in the waters of Hoopers Inlet in the Pacific coast of the South Island's Otago Peninsula. On that short December summer night, aurora australis also gave luminous, green and reddish hues to the sky above the hills. An upper atmospheric glow distinct from the aurora excited by collisions with energetic particles, pale greenish bands of airglow caused by a cascade of chemical reactions excited by sunlight can be traced in diagonal bands near the top left.

ASTRONOMY - 183 Days in the Sun

 2023 December 22

183 Days in the Sun
Image Credit & Copyright: José Zarcos Palma

Explanation: A single 183 day exposure with a pinhole camera and photographic paper resulted in this long-duration solargraph. Recorded from solstice to solstice, June 21 to December 21, in 2022, it follows the Sun's daily arcing path through planet Earth's skies from Mertola, Portugal. On June 21, the Sun's highest point and longest arc represents the longest day and the astronomical beginning of summer in the northern hemisphere. The solstice date with the fewest hours of daylight is at the beginning of winter in the north, corresponding to the Sun's shortest and lowest arc in the 2022 solargraph. For 2023, the northern winter solstice was on December 22 at 3:27 UTC. That's December 21 for North America time zones.

ASTRONOMY - Geminids over China's Nianhu Lake

 2023 December 17

Geminids over China's Nianhu Lake
Image Credit & Copyright: Hongyang Luo

Explanation: Where are all of these meteors coming from? In terms of direction on the sky, the pointed answer is the constellation of Gemini. That is why the major meteor shower in December is known as the Geminids -- because shower meteors all appear to come from a radiant toward Gemini. Three dimensionally, however, sand-sized debris expelled from the unusual asteroid 3200 Phaethon follows a well-defined orbit about our Sun, and the part of the orbit that approaches Earth is superposed in front of the constellation of Gemini. Therefore, when Earth crosses this orbit, the radiant point of falling debris appears in Gemini. Featured here is a composite of many images taken a few days ago through dark skies from Nianhu Lake in China. Over 100 bright meteor streaks from the Geminids meteor shower are visible.

AERONAUTIQUE - Les plus gros avions du monde - Antonov An-124 (Condor)

D'une capacité de 120 tonnes de fret sur une distance de 5.400 km, l'Antonov An-124 est le plus gros avion de transport civil et militaire du monde produit en série. Surnommé « Condor » à l'OTAN, il permet de transporter des charges hors norme telles que des locomotives, des grues, des satellites, des bateaux... et même un obélisque éthiopien, en 2005. L'armée française y a, elle-même, recours de temps en temps. Conçu dans les années 1980, le quadriréacteur a été modernisé plusieurs fois et peut être chargé par le nez ou par l'arrière avec des rampes de chargement spéciales.

Longueur : 68,9 mètres

Envergure : 73,3 mètres

Premier vol : 1982

FuturaSciences

LA FRANCE A L'AFFICHE - Place du Capitole - Toulouse

Le capitole, place emblématique de la ville de Toulouse. Egalement la place de l’hôtel de ville, très beau monument tout en longueur.

Doz

ASTRONOMY - Crescent Enceladus

 2023 December 16

Crescent Enceladus
Image Credit: Cassini Imaging Team, SSI, JPL, ESA, NASA

Explanation: Peering from the shadows, the Saturn-facing hemisphere of tantalizing inner moon Enceladus poses in this Cassini spacecraft image. North is up in the dramatic scene captured during November 2016 as Cassini's camera was pointed in a nearly sunward direction about 130,000 kilometers from the moon's bright crescent. In fact, the distant world reflects over 90 percent of the sunlight it receives, giving its surface about the same reflectivity as fresh snow. A mere 500 kilometers in diameter, Enceladus is a surprisingly active moon. Data and images collected during Cassini's flybys have revealed water vapor and ice grains spewing from south polar geysers and evidence of an ocean of liquid water hidden beneath the moon's icy crust.

AERONAUTIQUE - Les plus gros avions du monde - Tupolev Tu-160 (Cygne blanc)

D'une masse au décollage atteignant 275 tonnes, le Tupolev Tu-160 (aussi surnommé « Cygne blanc ») affiche une vitesse maximale de plus de 2.000 km/h et peut emporter jusqu'à 40 tonnes d'armements (missiles de croisière, ogives nucléaires...). Mis en service en 1987 lors de la guerre froide, ce bombardier russe est le plus puissant avion de combat du monde et possède une autonomie allant jusqu'à 18.000 km avec un ravitaillement en vol. Il est loin d'avoir dit son dernier mot : une toute nouvelle version avec une motorisation, des systèmes de défense et de communication dernier cri, est en cours de production.

FuturaSciences

ASTRONOMY - Betelgeuse Eclipsed

 2023 December 15

Betelgeuse Eclipsed
Image Credit & Copyright: Sebastian Voltmer

Explanation: Asteroid 319 Leona cast a shadow across planet Earth on December 12, as it passed in front of bright star Betelgeuse. But to see everyone's favorite red giant star fade this time, you had to stand near the center of the narrow shadow path starting in central Mexico and extending eastward across southern Florida, the Atlantic Ocean, southern Europe, and Eurasia. The geocentric celestial event is captured in these two panels taken at Almodovar del Rio, Spain from before (left) and during the asteroid-star occultation. In both panels Betelgeuse is seen above and left, at the shoulder of the familiar constellation Orion. Its brightness diminishes noticeably during the exceedingly rare occultation when, for several seconds, the giant star was briefly eclipsed by a roughly 60 kilometer diameter main-belt asteroid.

ASTRONOMY - Supernova Remnant Cassiopeia A

 2023 December 14

Supernova Remnant Cassiopeia A
Image Credit: NASA, ESA, CSA, STScI; D. Milisavljevic (Purdue University), T. Temim (Princeton University), I. De Looze (University of Gent)

Explanation: Massive stars in our Milky Way Galaxy live spectacular lives. Collapsing from vast cosmic clouds, their nuclear furnaces ignite and create heavy elements in their cores. After only a few million years for the most massive stars, the enriched material is blasted back into interstellar space where star formation can begin anew. The expanding debris cloud known as Cassiopeia A is an example of this final phase of the stellar life cycle. Light from the supernova explosion that created this remnant would have been first seen in planet Earth's sky about 350 years ago, although it took that light 11,000 years to reach us. This sharp NIRCam image from the James Webb Space Telescope shows the still hot filaments and knots in the supernova remnant. The whitish, smoke-like outer shell of the expanding blast wave is about 20 light-years across, while the bright speck near center is a neutron star, the incredibly dense, collapsed remains of the massive stellar core. Light echoes from the massive star's cataclysmic explosion are also identified in Webb's detailed image of supernova remnant Cassiopeia A.