ASTRONOMY - Fireball over Iceland

 2023 September 16

Fireball over Iceland
Image Credit & Copyright: Jennifer Franklin

Explanation: On September 12, from a location just south of the Arctic Circle, stones of Iceland's modern Arctic Henge point skyward in this startling scene. Entertaining an intrepid group of aurora hunters during a geomagnetic storm, alluring northern lights dance across the darkened sky when a stunning fireball meteor explodes. Awestruck, the camera-equipped skygazers captured video and still images of the boreal bolide, at its peak about as bright as a full moon. Though quickly fading from view, the fireball left a lingering visible trail or persistent train. The wraith-like trail was seen for minutes wafting in the upper atmosphere at altitudes of 60 to 90 kilometers along with the auroral glow.

AERONAUTIQUE - LES INVENTIONS QUI N'ONT JAMAIS VOLE - Le manteau parachute de Franz Reichelt

Tristement célèbre, Franz Reichelt, aussi appelé le « Flying Taylor », a inventé le manteau parachute. Une invention tellement sûre qu'il décida de l'étrenner en grande pompe en sautant de la Tour Eiffel. Vous l'aurez compris, si cette invention fait partie de notre top 10, c'est parce qu'elle n'a jamais fonctionné. Franz Reichelt fut tué sur le coup.

FuturaSciences

ASTRONOMY - Venus, Moon, and the Smoking Mountain

 2023 September 15

Venus, Moon, and the Smoking Mountain
Image Credit & Copyright: Luis Miguel Meade Rodríguez

Explanation: Venus has returned as a brilliant morning star. From a window seat on a flight to Mexico City, the bright celestial beacon was captured just before sunrise in this astronomical snapshot, taken on September 12. Venus, at the upper right, shared the early predawn skies with an old crescent Moon. Seen from this stratospheric perspective, both mountain peaks and clouds appear in silhouette along a glowing eastern horizon. The dramatic, long, low cloud bank was created by venting from planet Earth's active volcano Popocatépetl.

AERONAUTIQUE - LES INVENTIONS QUI N'ONT JAMAIS VOLE - La vis aérienne de Léonard de Vinci

Si Léonard de Vinci a été précurseur dans de nombreux domaines, bon nombre de ses inventions n'ont jamais pu fonctionner. Voici l'exemple de la vis aérienne qui prédestine l'hélicoptère. Elle a été conçue comme une toupie. Sans l'aide d'une queue, elle n'aurait pu faire autrement que de tourbillonner sans pouvoir être dirigée. Fabriquée entre 1487 et 1490, cet engin vole verticalement. Un souci cependant : Léonard de Vinci n'a pas pensé à la force de propulsion !

FuturaSciences

ASTRONOMY - NGC 4632: Galaxy with a Hidden Polar Ring

 2023 September 13

NGC 4632: Galaxy with a Hidden Polar Ring
Credit: Jayanne English (U. Manitoba), Nathan Deg (Queen's University) & WALLABY Survey, CSIRO/ASKAP, NAOJ/Subaru Telescope; Text: Jayanne English (U. Manitoba)

Explanation: Galaxy NGC 4632 hides a secret from optical telescopes. It is surrounded by a ring of cool hydrogen gas orbiting at 90 degrees to its spiral disk. Such polar ring galaxies have previously been discovered using starlight. However, NGC 4632 is among the first in which a radio telescope survey revealed a polar ring. The featured composite image combines this gas ring, observed with the highly sensitive ASKAP telescope, with optical data from the Subaru telescope. Using virtual reality, astronomers separated out the gas in the main disk of the galaxy from the ring, and the subtle color gradient traces its orbital motion. Why do polar rings exist? They could be material pulled from one galaxy as it gravitationally interacts with a companion. Or hydrogen gas flows along the filaments of the cosmic web and accretes into a ring around a galaxy, some of which gravitationally contracts into stars.

AERONAUTIQUE - LES INVENTIONS QUI N'ONT JAMAIS VOLE - Le navire volant de Bartolomeu Lourenço de Gusmão

 

Considéré comme le père de l'aérostation, Bartolomeu Lourenço de Gusmão, inventeur brésilien, a voulu présenter ses projets de ballons volants à la cour d'Espagne. Ces petites montgolfières avant l'heure étaient censées monter grâce à la chaleur. Le premier essai fut un échec cuisant : l'engin s'enflamma avant même d'avoir décollé ! Cependant, même s'ils n'ont jamais pu transporter d'Hommes, ces ballons ont fini par voler de quelques mètres. L'intérêt était cependant trop réduit et le projet a donc été abandonné.

FuturaSciences

ASTRONOMY - Beautiful Comet Nishimura

 2023 September 11

Beautiful Comet Nishimura
Credit & Copyright: Petr Horálek / Institute of Physics in Opava

Explanation: This scene would be beautiful even without the comet. By itself, the sunrise sky is an elegant deep blue on high, with faint white stars peeking through, while near the horizon is a pleasing tan. By itself, the foreground hills of eastern Slovakia are appealingly green, with the Zadňa hura and Veľká hora hills in the distance, and with the lights of small towns along the way. Venus, by itself on the right, appears unusually exquisite, surrounded by a colorful atmospheric corona. But what attracts the eye most is the comet. On the left, in this composite image taken just before dawn yesterday morning, is Comet Nishimura. On recent mornings around the globe, its bright coma and long ion tail make many a morning panoramic photo unusually beautiful. Tomorrow, C/2023 P1 (Nishimura) will pass its nearest to the Earth for about the next 434 years.

ASTRONOMY - An Annular Solar Eclipse over New Mexico

 2023 September 10

An Annular Solar Eclipse over New Mexico
Credit & Copyright: Colleen Pinski

Explanation: What is this person doing? In 2012, an annular eclipse of the Sun was visible over a narrow path that crossed the northern Pacific Ocean and several western US states. In an annular solar eclipse, the Moon is too far from the Earth to block out the entire Sun, leaving the Sun peeking out over the Moon's disk in a ring of fire. To capture this unusual solar event, an industrious photographer drove from Arizona to New Mexico to find just the right vista. After setting up and just as the eclipsed Sun was setting over a ridge about 0.5 kilometers away, a person unknowingly walked right into the shot. Although grateful for the unexpected human element, the photographer never learned the identity of the silhouetted interloper. It appears likely that the person is holding a circular device that would enable them to get their own view of the eclipse. The shot was taken at sunset on 2012 May 20 at 7:36 pm local time from a park near Albuquerque. Next month, on October 14, a different narrow swath across North and South America will be exposed to a different annular solar eclipse, if the sky is clear. Simultaneously, cloud-free observers almost anywhere on either continent will be able to see a partial solar eclipse.

ASTRONOMY - Comet Nishimura Grows

 2023 September 9

Comet Nishimura Grows
Credit & Copyright: Peter Kennett

Explanation: Comet Nishimura is growing. More precisely, the tails C/2023 P1 (Nishimura) are growing as it nears the Sun. Discovered only last month, the comet is already near naked eye brightness as it now moves inside the Earth's orbit. The comet will be nearest the Earth next week, but nearest the Sun the week after -- on September 17. Speculation holds that expelled ice and dust from Comet Nishimura's last visit to the inner Solar System may have created the Sigma Hydrids meteor shower which peaks yearly in December. If so, then this meteor shower may become more active, refreshed with new comet debris. Pictured, Comet Nishimura was captured from Edgewood, New Mexico, USA four nights ago, showing a long ion tail structured by interactions with the Sun's wind. Look for this comet near your eastern horizon just before sunrise for the next few mornings, but very near your western horizon just after sunset next week -- as its coma continues to brighten and its tails continue to grow.

MUSIC - Dmitri Chostakovitch - Valse n° 2

"Valse numéro 2"