Science et Vie - Ciel de juillet : une éclipse totale sous le signe de mars - Espace

Le 27 juillet 2018 restera dans les annales astronomiques comme la nuit où une éclipse totale de Lune a eu lieu au moment où Mars était au plus près de la Terre : un spectacle prodigieux, à ne manquer sous aucun prétexte.

Le ciel de juillet sera, comme ce mois de juin, dominé par les planètes : Vénus au couchant, puis Jupiter en début de soirée, enfin Saturne et Mars au cœur de la nuit... Une magnifique et brillante horlogerie cosmique, réglée par le tic-tac plus rapide de la Lune, qui croisera Vénus le 15 et le 16, Jupiter le 20, Saturne le 24 et enfin Mars... le 27 juillet.

Sauf que par un extraordinaire hasard du calendrier cosmique, cette nuit du 27 verra la Pleine Lune, totalement éclipsée, luire aux côtés de la planète Mars, qui brillera alors d'un éclat exceptionnel. En effet, Mars sera alors au plus près de la Terre, à seulement 57 millions de kilomètres, ce qui n'arrive que tous les quinze ans. La magnitude - c'est-à-dire l'éclat, dans le langage des astronomes - de Mars sera de -2.8, l'astre, véritable rubis céleste, brillera plus de dix fois plus que les brillantes étoiles qui l'environnent, comme Antarès, Altaïr, Arcturus, Véga ou Deneb.

Jean-Luc Dauvergne - Noctilucent Clouds over Paris Fireworks - Astronomy picture of the day - 2018 July 11

Noctilucent Clouds over Paris Fireworks 
Video Credit & Copyright: Jean-Luc Dauvergne (Ciel et Espace);

Explanation: It's northern noctilucent cloud season -- perhaps a time to celebrate! Composed of small ice crystals forming only during specific conditions in the upper atmosphere, noctilucent clouds may become visible at sunset during late summer when illuminated by sunlight from below. Noctilucent clouds are the highest clouds known and now established to be polar mesospheric clouds observed from the ground. Although observed with NASA's AIM satellitesince 2007, much about noctilucent clouds remains unknown and so a topic of active research. The featured time-lapse video shows expansive and rippled noctilucent clouds wafting over Paris, France, during a post-sunset fireworks celebration on Bastille Day in 2009 July. This year, several locations are already reporting especially vivid displays of noctilucent clouds.

John Chumack - Road to Mars - Astronomy picture of the day - 2018 July 9

Road to Mars 
Image Credit & Copyright: John Chumack

Explanation: What's that light at the end of the road? Mars. This is a good month to point out Mars to your friends and family because our neighboring planet will not only be its brightest in 15 years, it will be visible for much of night.During this month, Mars will be about 180 degrees around from the Sun, and near the closest it ever gets to planet Earth. In terms of orbits, Mars is also nearing the closest point to the Sun in its elliptical orbit, just as Earth moves nearly between it and the Sun -- an alignment known as perihelic opposition. In terms of viewing, orange Mars will rise in the east just as the Sun sets in the west, on the opposite side of the sky. Mars will climb in the sky during the night, reach its highest near midnight, and then set in the west just as the Sun begins to rise in the east. The red planet was captured setting beyond a stretch of road in Arches National Park in mid-May near Moab, Utah, USA.

Nasa : The Extraordinary Spiral in LL Pegasi - Astronomy picture of the day - 2018 July 8

The Extraordinary Spiral in LL Pegasi 
Image Credit: NASA, ESA, Hubble, HLA; Processing & Copyright: Domingo Pestana & Raul Villaverde

Explanation: What created the strange spiral structure on the upper left? No one is sure, although it is likely related to a star in a binary star system entering the planetary nebula phase, when its outer atmosphere is ejected. The huge spiral spans about a third of a light year across and, winding four or five complete turns, has a regularity that is without precedent. Given the expansion rate of the spiral gas, a new layer must appear about every 800 years, a close match to the time it takes for the two stars to orbit each other. The star system that created it is most commonly known as LL Pegasi, but also AFGL 3068. The unusual structure itself has been cataloged as IRAS 23166+1655. The featured image was taken in near-infrared light by the Hubble Space Telescope. Why the spiral glows is itself a mystery, with a leading hypothesis being illumination by light reflected from nearby stars.

Ruslan Merzlyakov - A Northern Summer's Night - Astronomy picture of the day - 2018 July 7

A Northern Summer's Night 
Image Credit & License: Ruslan Merzlyakov (RMS Photography)

Explanation: Near a summer's midnight a mist haunts the river bank in this dreamlike skyscape taken on July 3rd from northern Denmark. Reddened light from the Sun a little below the horizon gives an eerie tint to low hanging clouds. Formed near the edge of space, the silvery apparitions above them are noctilucent or night shining clouds. The icy condensations on meteoric dust or volcanic ash are still in full sunlight at the extreme altitudes of the mesophere. Usually seen at high latitudes in summer months, wide spread displays of the noctilucent clouds are now being reported.

Nasa - Charon: Moon of Pluto - Astronomy picture of the day - 2018 July 6

Charon: Moon of Pluto 
Image Credit: NASA, Johns Hopkins Univ./APL, Southwest Research Institute, U.S. Naval Observatory

Explanation: A darkened and mysterious north polar region known to some as Mordor Macula caps this premier high-resolution view. The portrait of Charon, Pluto's largest moon, was captured by New Horizons near the spacecraft's closest approach on July 14, 2015. The combined blue, red, and infrared data was processed to enhance colors and follow variations in Charon's surface properties with a resolution of about 2.9 kilometers (1.8 miles). A stunning image of Charon's Pluto-facing hemisphere, it also features a clear view of an apparently moon-girdling belt of fractures and canyons that seems to separate smooth southern plains from varied northern terrain. Charon is 1,214 kilometers (754 miles) across. That's about 1/10th the size of planet Earth but a whopping 1/2 the diameter of Pluto itself, and makes it the largest satellite relative to its parent body in the Solar System. Still, the moon appears as a small bump at about the 1 o'clock position on Pluto's disk in the grainy, negative,telescopic picture inset at upper left. That view was used by James Christy and Robert Harrington at the U.S. Naval Observatory in Flagstaff to discover Charon 40 years ago in June of 1978.

Carl Orff - "O Fortuna ~ Carmina Burana" - Slides - Music

"O Fortuna ~ Carmina Burana"

Steve Cullen - Shadow Rise on the Inside Passage - Astronomy picture of the day - 2018 July 5

Shadow Rise on the Inside Passage 
Image Credit & Copyright: Steve Cullen

Explanation: At sunset look east not west. As Earth's dark shadow rises from the eastern horizon, faint and subtle colors will appear opposite the setting Sun. This beautiful evening sea and skyscape records the reflective scene from a cruise on the well-traveled Alaskan Inside Passage in the Pacific Northwest. Along the horizon the fading sunset gives way to the the pinkish anti-twilight arch, more poetically known as the Belt of Venus. Often overlooked at sunset in favor of the brighter western horizon, the lovely arch is tinted by filtered sunlight backscattered in the dense atmosphere, hugging the planet's rising blue-grey shadow.

Ji-Hoon Kim - An Airplane in Front of the Moon - Astronomy picture of the day - 2018 July 3

An Airplane in Front of the Moon 
Image Credit & Copyright: Ji-Hoon Kim

Explanation: If you look closely at the Moon, you will see a large airplane in front of it. Well, not always. OK, hardly ever. Actually, to capture an image like this takes precise timing, an exposure fast enough to freeze the airplane and not overexpose the Moon -- but slow enough to see both, a steady camera, and luck -- because not every plane that approaches the Moon crosses in front. Helpful equipment includes a camera with fast continuous video mode and a mount that automatically tracks the Moon. The featured fleeting superposition was captured from Seoul, South Korea two weeks ago during a daytime waxing gibbous moonrise. Within 1/10th of a second, the airplane crossing was over.

Fresh Tiger Stripes on Saturn's Enceladus - Astronomy picture of the day - 2018 July 1

Fresh Tiger Stripes on Saturn's Enceladus 
Image Credit: NASA, ESA, JPL, SSI, Cassini Imaging Team

Explanation: Do underground oceans vent through the tiger stripes on Saturn's moon Enceladus? Long features dubbed tiger stripes are known to be spewing ice from the moon's icy interior into space, creating a cloud of fine ice particles over the moon's South Pole and creating Saturn's mysterious E-ring. Evidence for this has come from the robot Cassini spacecraft that orbited Saturn from 2004 to 2017. Pictured here, a high resolution image of Enceladus is shown from a close flyby. The unusual surface features dubbed tiger stripes are visible in false-color blue. Why Enceladus is active remains a mystery, as the neighboring moon Mimas,approximately the same size, appears quite dead. Arecent analysis of ejected ice grains has yielded evidence that complex organic molecules exist inside Enceladus. These large carbon-rich molecules bolster -- but do not prove -- that oceans under Enceladus' surface could contain life.