ASTRONOMY - Perseverance in Jezero Crater's Delta

 2022 September 17

Perseverance in Jezero Crater's Delta
Image Credit: NASA, JPL-Caltech, MSSS, ASU

Explanation: The Perseverance rover's Mastcam-Z captured images to create this mosaic on August 4, 2022. The car-sized robot was continuing its exploration of the fan-shaped delta of a river that, billions of years ago, flowed into Jezero Crater on Mars. Sedimentary rocks preserved in Jezero's delta are considered one of the best places on Mars to search for potential signs of ancient microbial life and sites recently sampled by the rover, dubbed Wildcat Ridge and Skinner Ridge, are at lower left and upper right in the frame. The samples taken from these areas were sealed inside ultra-clean sample tubes, ultimately intended for return to Earth by future missions. Starting with the Pathfinder Mission and Mars Global Surveyor in 1997, the last 25 years of a continuous robotic exploration of the Red Planet has included orbiters, landers, rovers, and a helicopter from planet Earth.

ASTRONOMY - Harvest Moon over Sicily

 2022 September 15

Harvest Moon over Sicily
Image Credit & Copyright: Dario Giannobile

Explanation: For northern hemisphere dwellers, September's Full Moon was the Harvest Moon. Reflecting warm hues at sunset it rises over the historic town of Castiglione di Sicilia in this telephoto view from September 9. Famed in festival, story, and song Harvest Moon is just the traditional name of the full moon nearest the autumnal equinox. According to lore the name is a fitting one. Despite the diminishing daylight hours as the growing season drew to a close, farmers could harvest crops by the light of a full moon shining on from dusk to dawn.

SANTé/MEDECINE - Encore trop de substances nocives dans les dentifrices

Une enquête de 60 millions de consommateurs a analysé la composition de douze produits de blanchiment des dents parmi les dentifrices les plus utilisés par les Français. Elle révèle que les deux tiers des produits en test sont à éviter et qu'aucune étude scientifique n'a validé l'efficacité des quatre autres.

Des substances utilisées pour éclaircir les dents sont pointées du doigt, toutes suspectées d'être cancérogènes. La principale utilisée, le peroxyde d'hydrogène, ne devrait pas représenter plus de 6 % de la composition des dentifrices de l'Union européenne. Cette substance pose entre autres des problèmes d'hypersensibilité dentaire, et présente le risque d'abîmer l'émail.

Plus de la moitié des dentifrices contenait du dioxyde de titane, pourtant interdit comme additif dans les denrées alimentaires depuis cette année. Sous forme de poudre, il est utilisé pour son caractère colorant blanc. Il est classé comme « cancérogène suspecté pour l'Homme de catégorie 2 par inhalation ».

Claire Manière

FuturaSciences

ASTRONOMY - Waves of the Great Lacerta Nebula

2022 September 14

Waves of the Great Lacerta Nebula
Image Credit & Copyright: Jarmo Ruuth, Telescope Live; Text: Ata Sarajedini (Florida Atlantic U., Astronomy Minute podcast)

Explanation: It is one of the largest nebulas on the sky -- why isn't it better known? Roughly the same angular size as the Andromeda Galaxy, the Great Lacerta Nebula can be found toward the constellation of the Lizard (Lacerta). The emission nebula is difficult to see with wide-field binoculars because it is so faint, but also usually difficult to see with a large telescope because it is so great in angle -- spanning about three degrees. The depth, breadth, waves, and beauty of the nebula -- cataloged as Sharpless 126 (Sh2-126) -- can best be seen and appreciated with a long duration camera exposure. The featured image is one such combined exposure -- in this case 10 hours over five different colors and over six nights during this past June and July at the IC Astronomy Observatory in Spain. The hydrogen gas in the Great Lacerta Nebula glows red because it is excited by light from the bright star 10 Lacertae, one of the bright blue stars just above the red-glowing nebula's center. The stars and nebula are about 1,200 light years distant. 

MERVEILLEUX MONDE SOUS-MARIN - Tortue verte

Mer Rouge - Egypte. Région de Marsa Alam.

Rencontre d'une plongeuse et d'une tortue verte (Chelonia mydas, green turtle), qui évolue sur de petits fonds sableux couverts d'un herbier de zostères dont elle se nourrit.

© Alexis Rosenfeld

FuturaSciences

VOIE LACTEE SUR TERRE - L'émerveillement du Plateau de Valensole

Des étendues infinies de champs de lavande, des fermes éparses très caractéristiques du plateau de Valensole et un parfum d'ambiance à couper le souffle. À l'est de la Durance, cette région naturelle, située dans les Alpes-de-Haute-Provence, au sud-ouest de Digne-les-Bains, près des Gorges du Verdon et du lac de Sainte-Croix au sud, est unique au monde. Son altitude moyenne est de 500 m et il s'étend sur 800 km2. Ces champs de lavande offrent aux visiteurs le calme et la beauté de la nature. À visiter de début juillet à début août, c'est le moment idéal où la lavande fleurit et que les champs s'illuminent d'un bleu violet profond.

© Delil Geyik

FuturaSciences

ASTRONOMY - A Long Snaking Filament on the Sun

 2022 September 13

A Long Snaking Filament on the Sun
Image Credit & Copyright: Alan Friedman (Averted Imagination)

Explanation: Earlier this month, the Sun exhibited one of the longer filaments on record. Visible as the bright curving streak around the image center, the snaking filament's full extent was estimated to be over half of the Sun's radius -- more than 350,000 kilometers long. A filament is composed of hot gas held aloft by the Sun's magnetic field, so that viewed from the side it would appear as a raised prominence. A different, smaller prominence is simultaneously visible at the Sun's edge. The featured image is in false-color and color-inverted to highlight not only the filament but the Sun's carpet chromosphere. The bright dot on the upper right is actually a dark sunspot about the size of the Earth. Solar filaments typically last from hours to days, eventually collapsing to return hot plasma back to the Sun. Sometimes, though, they explode and expel particles into the Solar System, some of which trigger auroras on Earth. The pictured filament appeared in early September and continued to hold steady for about a week.

ASTRONOMY - Red Sprite Lightning over the Czech Republic

 2022 September 12

Red Sprite Lightning over the Czech Republic
Image Credit & Copyright: Daniel Ščerba

Explanation: What are those red filaments in the sky? They are a rarely seen form of lightning confirmed only about 35 years ago: red sprites. Research has shown that following a powerful positive cloud-to-ground lightning strike, red sprites may start as 100-meter balls of ionized air that shoot down from about 80-km high at 10 percent the speed of light. They are quickly followed by a group of upward streaking ionized balls. The featured image was taken late last month from the Jeseniky Mountains in northern Moravia in the Czech Republic. The distance to the red sprites is about 200 kilometers. Red sprites take only a fraction of a second to occur and are best seen when powerful thunderstorms are visible from the side.

ASTRONOMY - Planets of the Solar System: Tilts and Spins

 2022 September 11

Planets of the Solar System: Tilts and Spins
Video Credit: NASA, Animation: James O'Donoghue (JAXA)

Explanation: How does your favorite planet spin? Does it spin rapidly around a nearly vertical axis, or horizontally, or backwards? The featured video animates NASA images of all eight planets in our Solar System to show them spinning side-by-side for an easy comparison. In the time-lapse video, a day on Earth -- one Earth rotation -- takes just a few seconds. Jupiter rotates the fastest, while Venus spins not only the slowest (can you see it?), but backwards. The inner rocky planets, across the top, most certainly underwent dramatic spin-altering collisions during the early days of the Solar System. The reasons why planets spin and tilt as they do remains a topic of research with much insight gained from modern computer modeling and the recent discovery and analysis of hundreds of exoplanets: planets orbiting other stars.

ASTRONOMY - Interstellar Voyager

 2022 September 9

Interstellar Voyager
Poster Illustration Credit: NASA, JPL-Caltech, Voyager

Explanation: Voyager 1 and Voyager 2 were launched in 1977 on a grand tour of the outer planets of the Solar System. They have become the longest operating and most distant spacecraft from Earth. Both have traveled beyond the heliosphere, the realm defined by the influence of the solar wind and the Sun's magnetic field. On the 45th year of their journey toward the stars Voyager 1 and 2 reached nearly 22 light-hours and 18 light-hours from the Sun respectively and remain the only spacecraft currently exploring interstellar space. Each spacecraft carries a 12-inch gold-plated copper disk with recordings of sounds, pictures and messages. The Golden Records are intended to communicate a story of life and culture on planet Earth, preserved in a medium that can survive an interstellar journey for a billion years.