Astronomy picture of the day - 2018 December 22 - A Cold December Night

A Cold December Night 

Image Credit & Copyright: Petr Horálek

Explanation: They say Orion always comes up sideways, and he does seem to on this cold December night. The bright stars of the familiar northern winter constellation lie just above the snowy tree tops surrounding a cozy cottage near the town of Ustupky in the Czech Republic. But Gemini's meteors also seem to rain on the wintry landscape. The meteor streaks are captured in exposures made near last Friday's peak of the annual Geminid meteor shower. They stream away from the shower's radiant above the trees, near the two bright stars of the zodiacal constellation of the Twins. Comet Wirtanen, a visitor to planet Earth's skies, is visible too. Look for its telltale greenish coma near the starsof the seven sisters.

Antonio Vivaldi - "L'inverno" - Musica - Slides

"L'inverno"

Extraordinary Solar Halos - Astronomy picture of the day - 2018 December 21

Extraordinary Solar Halos 

Image Credit & Copyright: Magnus Edback

Explanation: Welcome to the December Solstice, the first day of winter in planet Earth's northern hemisphere and summer in the south. To celebrate, consider this extraordinary display of beautiful solar ice halos! More common than rainbows, simple ice halos can be easy to spot, especially if you can shade your eyes from direct sunlight. Still it's extremely rare to see anything close to the complex of halos present in this astounding scene. Captured at lunchtime on a cold December 14 near Utendal, Sweden the image includes the relatively ordinary 22 degree halo, sundogs (parhelia) and sun pillars. The extensive array of rarer halos has been identified along with previously unknown features. All the patterns are generated as sunlight (or moonlight) is reflected and refracted in flat six-sided water ice crystals in Earth's atmosphere. In this case, likely local contributors to the atmospheric ice crystals are snow making machines operating at at nearby ski center.

Red Nebula, Green Comet, Blue Stars - Astronomy picture of the day - 2018 December 20

Red Nebula, Green Comet, Blue Stars 
Image Credit & Copyright: Tom Masterson (Grand Mesa Observatory)

Explanation: This festively colored skyscape was captured in the early morning hours of December 17, following Comet Wirtanen's closest approach to planet Earth. The comet was just visible to the eye. The lovely green color of its fluorescing cometary atmosphere or coma is brought out here only by adding digital exposures registered on the comet's position below the Pleiades star cluster. The exposures also bring out blue starlight reflected by the dust clouds surrounding the young Pleiades stars. Gaze (toward the left) across dusty dark nebulae along the edge of the Perseus molecular cloud and you'll travel to emission nebula NGC 1499, also known as the California nebula. Too faint for the eye, the cosmic cloud's pronounced reddish glow is from electrons recombining with ionized hydrogen atoms. Around December 23rd, Comet Wirtanen should be easy to find with binoculars when it sweeps close to bright star Capella in the northern winter constellation Auriga, the Charioteer.

A Rainbow Geminid Meteor - Astronomy picture of the day - 2018 December 19

A Rainbow Geminid Meteor 
Image Credit & Copyright: Dean Rowe

Explanation: Meteors can be colorful. While the human eye usually cannot discern many colors, cameras often can. Pictured is a Geminid captured by camera during last week's meteor shower that was not only impressively bright, but colorful. The radiant grit cast off by asteroid 3200 Phaethon blazed a path across Earth's atmosphere longer than 60 times the angular diameter of the Moon. Colors in meteors usually originate from ionized elements released as themeteor disintegrates, with blue-green typically originating from magnesium, calcium radiating violet, and nickel glowing green. Red, however, typically originates from energized nitrogen and oxygen in the Earth's atmosphere. This brightmeteoric fireball was gone in a flash -- less than a second -- but it left a wind-blown ionization trail that remained visible for several minutes, the start of which can be seen here.

Gallery: Geminid Meteors 2018 

Methane Bubbles Frozen in Lake Baikal - Astronomy picture of the day - 2018 December 18

Methane Bubbles Frozen in Lake Baikal 
Image Credit & Copyright: Kristina Makeeva

Explanation: What are these bubbles frozen into Lake Baikal? Methane. Lake Baikal, a UNESCO World Heritage Site in Russia, is the world's largest (by volume), oldest, and deepest lake, containing over 20% of the world's fresh water. The lake is also a vast storehouse of methane, a greenhouse gas that, if released, could potentially increase the amount of infrared light absorbed by Earth's atmosphere, and so increase the average temperature of the entire planet. Fortunately, the amount of methane currently bubbling out is not climatologically important. It is not clear what would happen, though, were temperatures to significantly increase in the region, or if the water level in Lake Baikalwere to drop. Pictured, bubbles of rising methane froze during winter into the exceptionally clear ice covering the lake.

Merry Christmas my friends

Merry Christmas my friends

Bientôt un vaccin contre le cancer ? - Santé/Médecine - Video

Des lymphocytes (en violet), cellules du système immunitaire, s'attaquent à des cellules cancéreuses.

Les vaccins nous protègent des virus ou des bactéries... et s'ils empêchaient de développer des cancers ? Dans certains labos de recherche, cette piste originale est bel et bien explorée !

Imaginez être protégé par une simple injection de la maladie la plus meurtrière en France : le cancer. Un vaccin qui ciblerait les cellules cancéreuses, entraînant le système immunitaire à détruire toute tumeur qui se développerait dans notre organisme. Est-ce un rêve ?

Comme le révèle Elsa Abdoun à Jérôme Bonaldi, les recherches de ce type sont beaucoup plus avancées qu'on ne le pense. Des premiers résultats très encourageants ont été atteints chez les souris ! Mais pour les biologistes, la tâche est complexe. Car il faut éviter à tout prix de retourner notre système immunitaire contre nos cellules saines — ce qu'on appelle une réaction auto-immune, très dangereuse...

Science & Vie

M31: The Andromeda Galaxy - Astronomy picture of the day - 2018 December 17

M31: The Andromeda Galaxy  
Image Credit & Copyright: Robert Gendler

Explanation: What is the nearest major galaxy to our own Milky Way Galaxy? Andromeda. In fact, our Galaxy is thought to look much like Andromeda. Together these two galaxies dominate the Local Group of galaxies. The diffuse light from Andromeda is caused by the hundreds of billions of stars that compose it. The several distinct stars that surround Andromeda's image are actually stars in our Galaxy that are well in front of the background object. Andromedais frequently referred to as M31 since it is the 31st object on Messier's list of diffuse sky objects. M31 is so distant it takes about two million years for light to reach us from there. Although visible without aid, the featured image of M31 is a digital mosaic of 20 frames taken with a small telescope. Much about M31 remains unknown, including exactly how long it will before it collides with our home galaxy.

Comet Wirtanen Passes by the Earth - Astronomy picture of the day - 2018 December 16

2018 December 16
Comet Wirtanen Passes by the Earth 
Image Credit & Copyright: Ruslan Merzlyakov (RMS Photography)

Explanation: Today Comet Wirtanen passes by the Earth. The kilometer-sized dirty snowball orbits the Sun every 5.4 years, ranging as far out as Jupiter and as close in as the Earth. Today Comet 46P/Wirtanen passes within only 31 lunar distances to the Earth, the closest approach in 70 years. If you know where to look (Taurus), you can see the comet through binoculars as an unusual blue smudge. Pictured a week ago, Comet Wirtanen was photographed in the sky beyond an old abandoned church in Skagen, Denmark. The image composite also captures the astrophotographer. After today, the comet will begin to fade as it recedes from the Earth and the Sun.