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. 

Science & Technology - Astronomy picture of the day : A Path North

A Path North
Image Credit & Copyright: Mario Konang

Explanation: What happens if you keep going north? The direction north on the Earth, the place on your horizon below the northern spin pole of the Earth -- around which other stars appear to slowly swirl, will remain the same. This spin-pole-of-the-north will never move from its fixed location on the sky -- night or day -- and its height will always match your latitude. The further north you go, the higher the north spin pole will appear. Eventually, if you can reach the Earth's North Pole, the stars will circle a point directly over your head. Pictured, a four-hour long stack of images shows stars trailing in circles around this north celestial pole. The bright star near the north celestial pole is Polaris, known as the North Star. The bright path was created by the astrophotographer's headlamp as he zigzagged up a hill just over a week ago in Lower Saxony, Germany. The astrophotographer can be seen, at times, in shadow. Actually, the Earth has two spin poles -- and much the same would happen if you started below the Earth's equator and went south.

Science & Technology - Astronomy picture of the day : NGC 1672: Barred Spiral Galaxy from Hubble

NGC 1672: Barred Spiral Galaxy from Hubble
Image Credit: Hubble Legacy Archive, NASA, ESA; Processing & Copyright: Daniel Nobre

Explanation: Many spiral galaxies have bars across their centers. Even our own Milky Way Galaxy is thought to have a modest central bar. Prominently barred spiral galaxy NGC 1672, featured here, was captured in spectacular detail in an image taken by the orbiting Hubble Space Telescope. Visible are dark filamentary dust lanes, young clusters of bright blue stars, red emission nebulas of glowing hydrogen gas, a long bright bar of stars across the center, and a bright active nucleus that likely houses a supermassive black hole. Light takes about 60 million years to reach us from NGC 1672, which spans about 75,000 light years across. NGC 1672, which appears toward the constellation of the Dolphinfish (Dorado), has been studied to find out how a spiral bar contributes to star formation in a galaxy's central regions.

Science & Technologie - Astronomie - La lune - 1

Située en moyenne à 384 400 kilomètres, la Lune est le seul satellite naturel de notre planète Terre. Avec ses 3 470 kilomètres de diamètre et parce qu’elle est très proche de nous comparés aux autres astres du ciel, la Lune offre de nombreuses choses à voir au curieux : forme changeante, détails de surface, rapprochements esthétiques avec d’autres astres… mais aussi quelques surprises qui font travailler l’imaginaire !

Croissant, quartier, pleine lune…

Si on voit aussi bien la Lune, il faut remercier le Soleil : c’est en effet lui qui l’éclaire et qui la rend visible à nos yeux. Vous aurez sans doute remarqué qu’au fil du temps, la Lune change de forme : parfois en fin croissant, puis en quartier, voire davantage, entièrement ronde ou même invisible ! Pourquoi ces changements ? Tout simplement parce que notre satellite tourne autour de la Terre en 28 jours environ et que depuis le point où nous l’observons, la partie éclairée par le Soleil n’est pas toujours la même.
sTELVISION

Science & Technologie - La Terre vue de l'Espace : Culture du raisin le long du fleuve Orange

Le fleuve Orange est le plus long fleuve d'Afrique du Sud (2.160 km) et sert en partie de frontière avec la Namibie voisine. À une centaine de kilomètres en amont de l'embouchure vers l'océan Atlantique, des programmes d'irrigation installés sur les rives de l'Orange profitent de cette source d'eau douce ainsi que des riches terres des plaines inondables. Ces rectangles aux différentes nuances de vert contrastent avec le reste du paysage désertique. La Namibie est le pays le plus aride de l'Afrique au sud du désert du Sahara et la majeure partie de son territoire est impropre à l'agriculture. C'est la culture du raisin qui domine dans cette région. Les conditions climatiques locales permettent au raisin de Namibie d'être récoltable deux à trois semaines avant celui qui est produit dans la région du Cap en Afrique du Sud. Remarque : rotation de l'image 90° à droite. 

© Nasa

Science & Technologie - Astronomy picture of the day : The Traffic in Taurus - 2020 April 03

The Traffic in Taurus

Image Credit & Copyright: Lionel Majzik

Explanation: There's a traffic jam in Taurus lately. On April 1, this celestial frame from slightly hazy skies over Tapiobicske, Hungary recorded an impressive pile up toward the zodiacal constellation of the Bull and the Solar System's ecliptic plane. Streaking right to left the International Space Station speeds across the bottom of the telescopic field of view. Wandering about as far from the Sun in planet Earth's skies as it can get, inner planet Venus is bright and approaching much slower, overexposed at the right. Bystanding at the upper left are the sister stars of the Pleiades. No one has been injured in the close encounter though, because it really isn't very close. Continuously occupied since November 2000, the space station orbits some 400 kilometers above the planet's surface. Venus, currently the brilliant evening star, is almost 2/3 of an astronomical unit away. A more permanent resident of Taurus, the Pleiades star cluster is 400 light-years distant.