ESPACE

Vénus est passée

Venus at the Edge 
Image Credit: JAXANASA, Lockheed MartinExplanation: As its June 6 2012 transit begins Earth’s sister planet crosses the edge of the Sun in this stunning view from the Hinode spacecraft. The timing of limb crossings during the rare transits was used historically to triangulate the distance to Venus and determine a value for the Earth-Sun distance called the astronomical unit. Still, modern space-based views like this one show the event against an evocative backdrop of the turbulent solar surface with prominences lofted above the Sun’s edge by twisting magnetic fields. Remarkably, the thin ring of light seen surrounding the planet’s dark silhouette is sunlight refracted by Venus’ thick atmosphere.

In this composite image provided by NASA, the SDO satellite captures the path sequence of the transit of Venus across the face of the sun at on June 5-6 as seen from space. The last transit was in 2004 and the next pair of events will not happen again until the year 2117 and 2125. (NASA via Getty Images)

A plane flies under a thin layer cloud crossing the sun as Venus moves past the sun are seen through a coelostat at the Griffith Observatory in Los Angeles on June 5. (Gene Blevins/Reuters)

Planet Venus, pictured as a black dot, is seen in transit across the Sun in New Delhi, India on June 6. Sky-gazers around the world held up their telescopes and viewing glasses to watch a once-in-a-lifetime event as Venus slid across the sun. (Manan Vatsyayana/AFP/Getty Images)

The planet Venus is seen in transit across the Sun during sunrise in Sofia, Bulgaria on June 6. (Nikolay Doychinov/AFP/Getty Images)

An image provided by NASA, the SDO satellite captures a ultra-high definition image of the Transit of Venus across the face of the sun on June 6 from space. The last transit was in 2004 and the next pair of events will not happen again until the year 2117 and 2125. (NASA)

Live: Watching for Venus to Cross the Sun
Image Credit: NASA/SDO & the AIA, EVE, and HMI teamsExplanation: Today Venus moves in front of the Sun. One way to follow this rare event is to actively reload the above live image of the Sun during the right time interval and look for an unusual circular dark dot. The smaller sprawling dark areas are sunspots. The circular dot is the planet Venus. The dark dot will only appear during a few very specific hours, from about 22:10 on 2012 June 5 through 4:50 2012 June 6, Universal Time. This transit is the rarest type of solar eclipse known — much more rare than an eclipse of the Sun by the Moon or even by the planet Mercury. In fact, the next transit of Venus across the Sun will be in 2117. Anyone with a clear view of the Sun can go outside and carefully view the transit for themselves by projecting sunlight through a hole in a card onto a wall. Because thisVenus transit is so unusual and visible from so much of the Earth, it is expected to be one of the more photographed celestial events in history. The above live image on the Sun is being taken by the Earth-orbiting Solar Dynamics Observatory and can be updated about every 15 minutes. Editor’s note: Since the transit has ended, the live image was replaced by one taken just before Venus crossed out of Sun.

Venus Transit 2012 
Image Credit & Copyright: Chris HetlageExplanation: Occurring in pairs separated by over a hundred years, there have now been only eight transits of Venus since the invention of the telescope in 1608. The next will be in December of 2117. But many modern telescopes and cameras were trained on this week’s Venus transit, capturing the planet in rare silhouette against the Sun. In this sharp telescopic view from Georgia, USA, a narrowbandH-alpha filter was used to show the round planetary disk against a mottled solar surface with dark filaments, sunspots, and prominences. The transit itself lasted for 6 hours and 40 minutes. Historically, astronomers used timings of the transit from different locations to triangulate the distance to Venus, while modern astronomers actively search for planets that transit distant suns.

When Venus Rises with the Sun 
Image Credit & Copyright: Emil IvanovExplanation: This dramatic telephoto view across the Black Sea on June 6 finds Venus rising with the Sun, the planet in silhouette against a ruddy and ragged solar disk. Of course, the reddened light is due to scattering in planet Earth’s atmosphere and the rare transit of Venus didn’t influence the strangely shaped and distorted Sun. In fact, seeing the Sun in the shape of an Etruscan Vase is relatively common, especially compared to Venus transits. At sunset and sunrise, the effects of atmospheric refraction enhanced by long, low, sight lines and strong atmospheric temperature gradients produce thevisual distortions and mirages. That situation is often favored by a sea horizon.


An image provided by NASA, the SDO satellite captures a ultra-high definition image of the Transit of Venus across the face of the sun at on June 5 from space. The last transit was in 2004 and the next pair of events will not happen again until the year 2117 and 2125. (NASA)

 

MORE ON

http://www.boston.com/bigpicture/2012/06/transit_of_venus.html

http://apod.nasa.gov/cgi-bin/apod/apod_search

Laisser un commentaire

Entrez vos coordonnées ci-dessous ou cliquez sur une icône pour vous connecter:

Logo WordPress.com

Vous commentez à l'aide de votre compte WordPress.com. Déconnexion / Changer )

Image Twitter

Vous commentez à l'aide de votre compte Twitter. Déconnexion / Changer )

Photo Facebook

Vous commentez à l'aide de votre compte Facebook. Déconnexion / Changer )

Photo Google+

Vous commentez à l'aide de votre compte Google+. Déconnexion / Changer )

Connexion à %s