PRATIQUE - La pelle remplit le seau

 

ASTRONOMY - Arecibo Telescope Collapse

 2020 December 9

Arecibo Telescope Collapse
Video Credit: Arecibo Observatory, NSF

Explanation: This was one great scientific instrument. Starting in 1963, the 305-meters across Arecibo Telescope in Puerto Rico USA reigned as the largest single-dish radio telescope in the world for over 50 years. Among numerous firsts and milestones, data from Arecibo has been used to measure the spin of Mercury, map the surface of Venus, discover the first planets outside of our Solar System, verify the existence of gravitational radiation, search for extraterrestrial intelligence, and, reportedly, locate hidden military radar by tracking their reflections from the Moon. Past its prime and in the process of being decommissioned, the Arecibo Telescope suffered a catastrophic structural collapse early this month, as seen in the featured composite video.

ASTRONOMY - Great Conjunction over Sicilian Lighthouse

 2020 December 8

Great Conjunction over Sicilian Lighthouse
Image Credit & Copyright: Kevin Saragozza

Explanation: Don’t miss the coming great conjunction. In just under two weeks, the two largest planets in our Solar System will angularly pass so close together in Earth's sky that the Moon would easily be able to cover them both simultaneously. This pending planetary passage -- on December 21 -- will be the closest since 1623. Jupiter and Saturn will remain noticeably bright and can already be seen together toward the southwest just after sunset. Soon after dusk is the best time to see them -- because they set below the horizon soon after. In mid-November, the Jovian giants were imaged together here about three degrees apart -- and slowly closing. The featured image, including a crescent moon, captured the dynamic duo beyond the Cape Murro di Porco Lighthouse in Syracuse, Sicily, Italy.

PRATIQUE - Enceinte puissante

 

METEOROLOGY - Mammatus Clouds over Mount Rushmore

 2020 December 7

Mammatus Clouds over Mount Rushmore
Image Credit & Copyright: Laure Mattuzzi

Explanation: What's that below those strange clouds? Presidents. If you look closely, you may recognize the heads of four former US Presidents carved into famous Mount Rushmore in South Dakota, USA. More obvious in the featured image are the unusual mammatus clouds that passed briefly overhead. Both were captured together by a surprised tourist with a quick camera in early September. Unlike normal flat-bottomed clouds which form when moist and calm air plateaus rise and cool, bumpy mammatus clouds form as icy and turbulent air pockets sink and heat up. Such turbulent air is frequently accompanied by a thunderstorm. Each mammatus lobe spans about one kilometer. The greater mountain is known to native Lakota Sioux as Six Grandfathers, deities responsible for the directions north, south, east, west, up, and down.

AERONAUTIQUE - Boeing - projet X48

Douglas dans les années 1990. Le projet s'est poursuivi sous la forme d'une collaboration avec la Nasa et l'université britannique de Cranfield pour un appareil à fuselage porteur. Après le X48A, resté dans les cartons, deux modèles réduits baptisés X48B ont été construits et testés en vol. Une autre version, le X48C, a été testé en vol également entre 2012 et 2013.

En 2011, Boeing a présenté ce projet à la Nasa dans le cadre de son étude sur les avions de 2025. On voit ici une image d'artiste avec deux types de motorisation. Les moteurs sont installés sur la partie supérieure, ce qui réduit le bruit perçu au sol. 

© Nasa, The Boeing Company

PRATIQUE - Vêtements parfumés

 

ASTRONOMY - M16: Pillars of Star Creation

 2020 December 6

M16: Pillars of Star Creation
Image Credit: NASA, ESA, Hubble Space Telescope, J. Hester, P. Scowen (ASU)

Explanation: These dark pillars may look destructive, but they are creating stars. This pillar-capturing image of the inside of the Eagle Nebula, taken with the Hubble Space Telescope in 1995, shows evaporating gaseous globules (EGGs) emerging from pillars of molecular hydrogen gas and dust. The giant pillars are light years in length and are so dense that interior gas contracts gravitationally to form stars. At each pillars' end, the intense radiation of bright young stars causes low density material to boil away, leaving stellar nurseries of dense EGGs exposed. The Eagle Nebula, associated with the open star cluster M16, lies about 7000 light years away. The pillars of creation have been imaged more recently in infrared light by Hubble, NASA's Spitzer Space Telescope, and ESA's Herschel Space Observatory -- showing new detail.

AERONAUTIQUE - Marcher sur l'eau

Dans les années 1900, une célèbre marque de chocolat leader sur son marché, Hildebrands, agrémentait ses tablettes de cartes postales imaginant l'an 2000. Celle-ci illustre la croyance selon laquelle, à l'aide de ballons gonflables, nous pourrions nous balader en marchant sur l'eau. Vous remarquerez les très pratiques petites chaussures-péniches en bois pour éviter de mouiller ses souliers.

© Hildebrands

ASTRONOMY - Mons Rumker in the Ocean of Storms

 2020 December 5

Mons Rumker in the Ocean of Storms
Image Credit & Copyright: Jean-Yves Letellier

Explanation: Mons Rumker, a 70 kilometer wide complex of volcanic domes, rises some 1100 meters above the vast, smooth lunar mare known as Oceanus Procellarum, the Ocean of Storms. Daylight came to the area late last month. The lunar terminator, the shadow line between night and day, runs diagonally across the left side in this telescopic close-up of a waxing gibbous Moon from November 27. China's Chang'e-5 mission landing site is also in the frame. The probe's lander-ascender combination touch down on the lunar surface within a region right of center and north of Mons Rumker's domes on December 1. On December 3 the ascender left the Ocean of Storms carrying 2 kilograms of lunar material for return to planet Earth.