ASTRONOMY - HH 211: Jets from a Forming Star

 2023 September 19

HH 211: Jets from a Forming Star
Credit: NASA, ESA, CSA, Webb; Processing: Tom Ray (DIAS Dublin)

Explanation: Do stars always create jets as they form? No one is sure. As a gas cloud gravitationally contracts, it forms a disk that can spin too fast to continue contracting into a protostar. Theorists hypothesize that this spin can be reduced by expelling jets. This speculation coincides with known Herbig-Haro (HH) objects, young stellar objects seen to emit jets -- sometimes in spectacular fashion. Pictured is Herbig-Haro 211, a young star in formation recently imaged by the Webb Space Telescope (JWST) in infrared light and in great detail. Along with the two narrow beams of particles, red shock waves can be seen as the outflows impact existing interstellar gas. The jets of HH 221 will likely change shape as they brighten and fade over the next 100,000 years, as research into the details of star formation continues.

ASTRONOMY - Moon Mountains Magnified during Ring of Fire Eclipse

 2023 September 17

Moon Mountains Magnified during Ring of Fire Eclipse
Credit & Copyright: Wang Letian (Eyes at Night)

Explanation: What are those dark streaks in this composite image of a solar eclipse? They are reversed shadows of mountains at the edge of the Moon. The center image, captured from Xiamen, China, has the Moon's center directly in front of the Sun's center. The Moon, though, was too far from the Earth to completely block the entire Sun. Light that streamed around the edges of the Moon is called a ring of fire. Images at each end of the sequence show sunlight that streamed through lunar valleys. As the Moon moved further in front of the Sun, left to right, only the higher peaks on the Moon's perimeter could block sunlight. Therefore, the dark streaks are projected, distorted, reversed, and magnified shadows of mountains at the Moon's edge. Bright areas are called Baily's Beads. Only people in a narrow swath across Earth's Eastern Hemisphere were able to view this full annular solar eclipse in 2020. Next month, though, a narrow swath crossing both North and South America will be exposed to the next annular solar eclipse. And next April, a total solar eclipse will be visible across North America.

ASTRONOMY - The Red Sprite and the Tree

 2023 September 18

The Red Sprite and the Tree
Credit & Copyright: Maxime Villaeys

Explanation: The sprite and tree could hardly be more different. To start, the red sprite is an unusual form of lightning, while the tree is a common plant. The sprite is far away -- high in Earth's atmosphere, while the tree is nearby -- only about a football field away. The sprite is fast -- electrons streaming up and down at near light's speed, while the tree is slow -- wood anchored to the ground. The sprite is bright -- lighting up the sky, while the tree is dim -- shining mostly by reflected light. The sprite was fleeting -- lasting only a small fraction of a second, while the tree is durable -- living now for many years. Both however, when captured together, appear oddly similar in this featured composite image captured early this month in France as a thunderstorm passed over mountains of the Atlantic Pyrenees.

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.