Science & Technologie - La Terre vue du ciel : L’île de Kyūshū au Japon

L'île de Kyūshū est la parfaite illustration de la complexité de l'œkoumène du Japon qui se trouve à l'intersection de quatre plaques tectoniques : le Pacifique, la mer des Philippines, l'Amérique du Nord, et l'Eurasie. Kyūshū se situe sur une zone de subduction où une plaque tectonique plonge sous une autre, donnant naissance à une topographie mêlant montagnes, plaines, volcans actifs (mont Unzen) et éteints (mont Tara).

Sur cette image satellite dont les couleurs ont été simulées, l'eau est bleue, la végétation verte et les zones urbaines sont en blanc et dégradé de bleu-gris. On peut ainsi se rendre compte de l'intrication complexe entre les zones habitées et montagneuses.

© Nasa

Science & Technology - Astronomy picture of the day : Around the World at Night

Around the World at Night
Video Credit & Copyright: Jeff Dai (TWAN, IDA), Music: Peter Jeremias

Explanation: Watch this video. In only a minute or so you can explore the night skies around planet Earth through a compilation of stunning timelapse sequences. The presentation will take you to sites in the United States, Germany, Russia, Iran, Nepal, Thailand, Laos and China. You might even catch the view from a small island in the southeastern Pacific Ocean. But remember that while you're home tonight, the night sky will come to you. Look up and celebrate the night during this International Dark Sky Week.

Science & Technology - Astronomy picture of the day : Lyrid Meteor Streak

2020 April 23

Lyrid Meteor Streak
Image Credit & Copyright: Zolt Levay

Explanation: Earth's annual Lyrid Meteor Shower peaked before dawn yesterday, as our fair planet plowed through debris from the tail of long-period comet Thatcher. In crisp, clear and moonless predawn skies over Brown County, Indiana this streak of vaporizing comet dust briefly shared a telephoto field of view with stars and nebulae along the Milky Way. Alpha star of the constellation Cygnus, Deneb lies near the bright meteor's path along with the region's dark interstellar clouds of dust and the recognizable glow of the North America nebula (NGC 7000). The meteor's streak points back to the shower's radiant, its apparent point of origin on the sky. That would be in the constellation

Science & Technology - Astronomy picture of the day : Planet Earth at Twilight

2020 April 22

Planet Earth at Twilight
Image Credit: ISS Expedition 2 Crew, Gateway to Astronaut Photography of Earth, NASA

Explanation: No sudden, sharp boundary marks the passage of day into night in this gorgeous view of ocean and clouds over our fair planet Earth. Instead, the shadow line or terminator is diffuse and shows the gradual transition to darkness we experience as twilight. With the Sun illuminating the scene from the right, the cloud tops reflect gently reddened sunlight filtered through the dusty troposphere, the lowest layer of the planet's nurturing atmosphere. A clear high altitude layer, visible along the dayside's upper edge, scatters blue sunlight and fades into the blackness of space. This picture was taken in June of 2001 from the International Space Station orbiting at an altitude of 211 nautical miles. Of course from home, you can check out the Earth Now.

Science & Tecnology - Astronomy picture of the day : IC 2944: The Running Chicken Nebula

IC 2944: The Running Chicken Nebula
Image Credit & Copyright: Juan Filas

Explanation: To some, it looks like a giant chicken running across the sky. To others, it looks like a gaseous nebula where star formation takes place. Cataloged as IC 2944, the Running Chicken Nebula spans about 100 light years and lies about 6,000 light years away toward the constellation of the Centaur (Centaurus). The featured image, shown in scientifically assigned colors, was captured recently in a 12-hour exposure. The star cluster Collinder 249 is visible embedded in the nebula's glowing gas. Although difficult to discern here, several dark molecular clouds with distinct shapes can be found inside the nebula.

Science & Technologie - La Terre vue de l'Espace : La ville de Christchurch en Nouvelle-Zélande

Deuxième plus grande ville de Nouvelle-Zélande, Christchurch est située sur la côte est de l'île du Sud, près de la pointe sud de la baie de Pegasus. Elle est bordée au nord par la rivière Waimakariri et au sud par la péninsule de Banks. L'île du Sud est parcourue de rivières en tresses qui charrient les roches arrachées aux Alpes du Sud et viennent nourrir les plaines alluviales de Canterbury. Ce type de rivières, faites de nombreuses connexions entre ses bras, est très rare. Hormis la Nouvelle-Zélande, on en trouve en Alaska, au Canada, et dans l'Himalaya. La péninsule de Banks se compose de deux volcans éteints qui se chevauchent, nommés Lyttelton et Akaroa. Inactifs depuis six millions d'années, ils se sont peu à peu érodés, passant d'une altitude de 1.500 à 500 mètres. On distingue deux grandes brèches dans les parois du cratère qui sont devenues des ports naturels, celui de Lyttelton au nord et celui d'Akaroa au sud. 

© Nasa

Science & Technology - Astronomy picture of the day : Moon Setting Behind Teide Volcano

Moon Setting Behind Teide Volcano
Video Credit & Copyright: Daniel López (El Cielo de Canarias); Music: Piano della Moon (Dan Silva)

Explanation: These people are not in danger. What is coming down from the left is just the Moon, far in the distance. Luna appears so large here because she is being photographed through a telescopic lens. What is moving is mostly the Earth, whose spin causes the Moon to slowly disappear behind Mount Teide, a volcano in the Canary Islands off the northwest coast of Africa. The people pictured are 16 kilometers away and many are facing the camera because they are watching the Sun rise behind the photographer. It is not a coincidence that a full moon rises just when the Sun sets because the Sun is always on the opposite side of the sky from a full moon. The featured video was made two years ago during the full Milk Moon. The video is not time-lapse -- this was really how fast the Moon was setting.

Science & Technology - Actualy picture of the day : The Horsehead Nebula in Infrared from Hubble

The Horsehead Nebula in Infrared from Hubble
Image Credit: NASA, ESA, and The Hubble Heritage Team (STScI/AURA)

1. Explanation: While drifting through the cosmos, a magnificent interstellar dust cloud became sculpted by stellar winds and radiation to assume a recognizable shape. Fittingly named the Horsehead Nebula, it is embedded in the vast and complex Orion Nebula (M42). A potentially rewarding but difficult object to view personally with a small telescope, the above gorgeously detailed image was taken in 2013 in infrared light by the orbiting Hubble Space Telescope in honor of the 23rd anniversary of Hubble's launch. The dark molecular cloud, roughly 1,500 light years distant, is cataloged as Barnard 33 and is seen above primarily because it is backlit by the nearby massive star Sigma Orionis. The Horsehead Nebula will slowly shift its apparent shape over the next few million years and will eventually be destroyed by the high energy starlight.

Science & Technology - Astronomy picture of the day : Full Moon of Spring

2020 April 10

Full Moon of Spring
Image Credit & Copyright: Jeff Dai (TWAN)

Explanation: From home this Full Moon looked bright. Around our fair planet it rose as the Sun set on April 7/8, the first Full Moon after the vernal equinox and the start of northern hemisphere spring. April's full lunar phase was also near perigee, the closest point in the Moon's elliptical orbit. In fact, it was nearer perigee than any other Full Moon of 2020 making it the brightest Full Moon of the year. To create the visual experience a range of exposures was blended to capture the emerging foreground foliage and bright lunar disk. The hopefull image of spring was recorded from a home garden in skies over Chongqing, China. 

Science & Technology - Astronomy picture of the day : Morning, Planets, Moon and Montreal

Morning, Planets, Moon and Montreal
Image Credit & Copyright: Arnaud Mariat

Explanation: Dawn's early light came to Montreal, northern planet Earth, on March 18, the day before the vernal equinox. At the end of that nearly equal night the Moon stands above a dense constellation of urban lights in this serene city and skyscape. Of course the Moon's waning crescent faces toward the rising Sun. Skygazers could easily spot bright Jupiter just above the Moon, close on the sky to a fainter Mars. Saturn, a telescopic favorite, is just a pinprick of light below and farther left of the closer conjunction of Moon, Jupiter and Mars. Near the ecliptic, even Mercury is rising along a line extended to the horizon from Jupiter and Saturn. The elusive inner planet is very close to the horizon though, and not quite visible in this morning's sky.