Launch of the Parker Solar Probe - Astronomy picture of the day - 2018 August 15

Launch of the Parker Solar Probe 
Image Credit & Copyright: John Kraus

Explanation: When is the best time to launch a probe to the Sun? The now historic answer -- which is not a joke because this really happened this past weekend -- was at night. Night, not only because NASA's Parker Solar Probe's (PSP) launch window to its planned orbit occurred, in part, at night, but also because most PSP instruments will operate in the shadow of its shield -- in effect creating its own perpetual night near the Sun. Before then, years will pass asthe PSP sheds enough orbital energy to approach the Sun, swinging past Venus seven times. Eventually, the PSP is scheduled to pass dangerously close to the Sun, within 9 solar radii, the closest ever. This close, the temperature will be 1,400 degrees Celsius on the day side of the PSP's Sun shield -- hot enough to melt many forms of glass. On the night side, though, it will be near room temperature. A major goal of the PSP's mission to the Sun is to increase humanity's understanding of the Sun's explosions that impact Earth's satellites and power grids. Pictured is the night launch of the PSP aboard the United Launch Alliances' Delta IV Heavy rocket early Sunday morning.

M86 in the Central Virgo Cluster - Astronomy picture of the day - 2018 August 14

M86 in the Central Virgo Cluster 
Image Credit & Copyright: Mark Hanson, Stan Watson Obs.

Explanation: Is there a bridge of gas connecting these two great galaxies? Quite possibly, but it is hard to be sure. M86 on the upper left is a giant elliptical galaxy near the center of the nearby Virgo Cluster of galaxies. Our Milky Way Galaxy is falling toward the Virgo Cluster, located about 50 million light years away. To the lower right of M86 is unusual spiral galaxy NGC 4438, which, together with angular neighbor NGC 4435, are known as the Eyes Galaxies(also Arp 120). Featured here is one of the deeper images yet taken of the region, indicating that red-glowing gas surrounds M86 and seemingly connects it to NGC 4438. The image spans about the size of the full moon. It is also known, however, that cirrus gas in our own Galaxy is superposed in front of the Virgo cluster, and observations of the low speed of this gas seem more consistent with this Milky Way origin hypothesis. A definitive answer may come from future research, which may also resolve how the extended blue arms of NGC 4435 were created.

Les dents d’un ancien requin gigantesque retrouvées en Australie - Paléontologie

Philip Mullaly se promenait sur la célèbre Great Ocean Road (Victoria), une zone réputée pour ses fossiles que vous retrouverez à environ 100 kilomètres de Melbourne, lorsqu’il fit la découverte. « Je marchais le long de la plage à la recherche de fossiles, je me suis retourné et j’ai vu une étincelle dans un rocher, puis j’ai vu un quart de la dent exposée, a-t-il raconté à l’AFP. J’ai été tout de suite enthousiaste, c’était simplement parfait, et je savais qu’il s’agissait d’une importante découverte qu’il fallait partager ».

« Ces dents ont une portée internationale, puisque c’est l’une des trois séries de dents de Carcharodon angustidens dans le monde, et c’est la première série découverte en Australie », explique le paléontologiste Erich Fitzgerald. Quasiment toutes les dents de requins retrouvées sont uniques, et il est en effet extrêmement rare de trouver plusieurs dents associées provenant du même requin.

Deux expéditions ont par la suite été menées pour creuser le site plus en profondeur. Plus d’une quarantaine de dents ont au final été découvertes. La plupart provenaient du méga-requin, mais plusieurs dents plus petites appartenaient également au requin à six dents (Hexanchus), un charognard qui évolue encore aujourd’hui. Pour Tim Ziegler (lui aussi paléontologiste) plusieurs petits requins se seraient alors acharnés sur la carcasse du plus gros, et quelques dents se seraient alors délogées au passage.

Science Post

Sur Mars, suivez le passage de la Terre ! - Espace

Cet été, la rédaction du magazine « Ciel & Espace » s’est délocalisée sur la planète rouge. Depuis la surface de Mars, l’observation du ciel profond ne change pas vraiment. Ce sont le ballet des satellites et le spectacle des planètes qui surprendront l’astronome amateur terrien.

En ce 10 novembre 2084, les occupants de la première base martienne s’apprêtent à suivre un phénomène inédit : le passage de la Terre devant le Soleil ! Un événement rarissime sur Mars : le précédent a eu lieu tout juste un siècle plus tôt, en 1984. Et pour le suivant, il faudra revenir en 2163 ! De leur position, par 25° de latitude nord entre Syrtis Major et Elysium Mons, les astronautes sont aux premières loges. Le passage de la planète bleue devant l’astre du jour offre une occasion en or de vérifier si nous sommes capables de détecter la vie sur Terre…/...

Ciel & Espace

The Pencil Nebula in Red and Blue - Astronomy picture of the day - 2018 August 13

The Pencil Nebula in Red and Blue 
Image Credit & Copyright: José Joaquín Perez

Explanation: This shock wave plows through interstellar space at over 500,000 kilometers per hour. Near the top and moving up in this sharply detailed color composite, thin, bright, braided filaments are actually long ripples in a cosmic sheet of glowing gas seen almost edge-on. Cataloged as NGC 2736, its elongated appearance suggests its popular name, the Pencil Nebula. The Pencil Nebula is about 5 light-years long and 800 light-years away, but represents only a small part of the Vela supernova remnant. The Vela remnant itself is around 100 light-years in diameter, the expanding debris cloud of a star that was seen to explode about 11,000 years ago. Initially, the shock wavewas moving at millions of kilometers per hour but has slowed considerably, sweeping up surrounding interstellar material. In the featured narrow-band, wide field image, red and blue colors track the characteristic glow of ionized hydrogen and oxygen atoms, respectively.

Meteor before Galaxy - Astronomy picture of the day - 2018 August 12

Meteor before Galaxy 
Image Credit & Copyright: Fritz Helmut Hemmerich

Explanation: What's that green streak in front of the Andromeda galaxy? A meteor. While photographing the Andromeda galaxy in 2016, near the peak of the Perseid Meteor Shower, a sand-sized rock from deep space crossed right in front of our Milky Way Galaxy's far-distant companion. The small meteor took only a fraction of a second to pass through this 10-degree field. The meteor flared several times while braking violently upon entering Earth's atmosphere. The green color was created, at least in part, by the meteor's gas glowing as it vaporized. Although the exposure was timed to catch a Perseids meteor, the orientation of the imaged streak seems a better match to a meteor from the Southern Delta Aquariids, a meteor shower that peaked a few weeks earlier. Not coincidentally, the Perseid Meteor Shower peaks again tonight.

Moon, Mars, and Milky Way - Astronomy picture of the day - 2018 August 11

Moon, Mars, and Milky Way 
Image Credit & Copyright: Taha Ghouchkanlu (TWAN)

Explanation: Just two weeks ago, dark skies over the desert in northern Iran held this alluring celestial vista. The dramatic digital mosaic finds the Moon and Mars alongside the Milky Way's dusty rifts, stars, and nebulae. Captured through a series of exposures to cover a range in brightness, that night's otherwise Full Moon is immersed in Earth's shadow. It actually appears fainter and redder than the Red Planet itself during the widely watched total lunar eclipse.For cosmic tourists, the skyscape also includes the Lagoon (M8) and Trifid (M20) nebulae and planet Saturn shining against the Milky Way's pale starlight. The Moon isn't quite done with its shadow play, though. Today, the New Moon partially eclipses the Sun for much of northern planet Earth.

Spiral Galaxy NGC 6744 -Astronomy picture of the day - 2018 August 10

Spiral Galaxy NGC 6744 
Image Credit & Copyright: Martin Pugh

Explanation: Beautiful spiral galaxy NGC 6744 is nearly 175,000 light-years across, larger than our own Milky Way. It lies some 30 million light-years distant in the southern constellation Pavo and appears as only a faint, extended object in small telescopes. We see the disk of the nearby island universe tilted towards our line of sight. This remarkably detailed galaxy portrait covers an area about the angular size of the full moon. In it, the giant galaxy's elongated yellowish core is dominated by the light from old, cool stars. Beyond the core, grand spiral arms are filled with young blue star clusters and speckled with pinkish star forming regions. An extended arm sweeps past a smaller satellite galaxy at the upper left. NGC 6744's galactic companion is reminiscent of the Milky Way's satellite galaxy the Large Magellanic Cloud.

Red Planet, Red Moon, and Mars - Astronomy picture of the day - 2018 August 9

Red Planet, Red Moon, and Mars 
Image Credit & Copyright: Alex Cherney (Terrastro, TWAN)

Explanation: Mars is also known as The Red Planet, often seen with a reddish tinge in dark night skies. Mars shines brightly at the upper left of this gorgeous morning twilight view from Mornington Peninsula, Victoria, Australia, but the Moon and planet Earth look redder still. Taken on July 27, the totally eclipsed Moon is setting. It looks reddened because the Earth's umbral shadow isn't completely dark. Instead Earth's shadow is suffused with a faint red light from all the planet's sunsets and sunrises seen from the perspective of an eclipsed Moon. The sunsets and sunrises are reddened because Earth's atmosphere scatters blue light more strongly than red, creating the faint bluish twilight sky. Of course, craggy seaside rocks also take on the reddened colors of this Australian sunrise.

Os Paises que mais seguiram este blogue desde o inicio - Estatisticas

U.S.A. - 2125

FRANCE - 1278

BRASIL - 452

ALEMANHA - 452

BELGICA - 358

CANADA - 332

EMIRADOS ARABES UNIDOS - 288

PORTUGAL - 221

PERU - 174

UCRÂNIA - 60