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July 19 2013

Ce soir, souriez, vous êtes photographiés ! - L'image d'astronomie du jour - APOD

Ce soir, souriez, vous êtes photographiés ! - L’image d’#astronomie du jour - APOD

Ce soir, entre 23h27 et 23h42, prenez une photo de Saturne comme celle-ci, prise le mois dernier avec au premier plan les ruines du temple d’Athena d’Assos, en Turquie. Tandis que la Lune se lève sur la gauche, Saturne est la brillante « étoile » en haut à droite, près de Spica, l’étoile la plus brillante de la constellation de la Vierge ( version légendée ici). Si vous prenez une #photo de Saturne ou lui adressez votre plus beau sourire en éclairant votre visage ce soir, vous pourrez la partager en ligne et la soumettre au projet « Saturn Mosaic ». Pourquoi ce soir, et spécialement entre 23h27 et 23h42 ? Parce que la sonde spatiale Cassini, qui se trouvera derrière Saturne par rapport au Soleil, sera 1h20 plus tard, le temps que la lumière franchisse les 1,44 milliard de kilomètre qui nous séparent de Saturne, en train de récolter les photons émis par les flashs de vos appareils !


February 26 2013

Confirmed: Cosmic Rays Come From Exploding Stars : 80beats



Scientists have known about these ridiculously energetic and high-velocity particles for nearly a hundred years. In daily life, cosmic rays may be familiar as the source of extra radiation airline passengers are exposed to. However scientists have been uncertain about where cosmic rays come from. The extreme conditions of temperature and speed that accompany supernovae and their remains made them a natural starting point for guesses. Now two separate Science papers finally provide evidence that cosmic rays do indeed come from supernovae remnants.


Reposted from02mysoup-aa 02mysoup-aa

February 23 2013

Play fullscreen
What Lessons to Learn from the Chelyabinsk Meteor?

From: setiinstitute

// oAnth: 30 minutes dense information about the actual available knowledge, predictabilty and possible further use of small earth near objects.

In case of your interest see also "Surface exploration of small solar system objects" :

Time: 30:00 More in Science & Technology
Reposted from02mysoup-aa 02mysoup-aa

February 20 2013


December 04 2012


August 18 2011


Russian telescope launch pulls national space program out of black hole - | 2011-07-19

The Zenit - 3F carrier rocket with the Spektr-R radio astronomy observatory aboard takes off from the Bakinour Cosmodrome.

Oleg Urusov/AFP/Newscom


Once it is fully operational, the new radio telescope will sync up with ground-based observatories to form the biggest telescope ever built. It will be known as RadioAstron, with a "dish" spanning 30 times the Earth's diameter. Experts say it will be able to deliver images from the remote corners of the universe at 10,000 times the resolution of the US Hubble Space Telescope.


"It's been planned since the 1980s, but has repeatedly fallen through for a variety of reasons. But now it's here, and we're bracing for all the new information it's going to deliver, especially about black holes," he says.

The space-based component is actually a small radio telescope, with a 10-meter dish that's far smaller than Earth-based radio telescopes, planted in an elliptical orbit about 340,000 kilometers (more than 212,000 miles) from Earth. But when its signals are combined with those of ground-based radio telescopes through a process known as interferometry, it effectively becomes one single telescope with a "dish" as large as the distance between its components, which will be able to deliver unprecedented pictures of mysterious cosmic phenomenon, such as quasars, pulsars, and supernovae.


Scientists from more than 20 countries will participate in RadioAstron's five-year mission, according to the Russian Space Agency.

Russia's space program fell on hard times after the collapse of the USSR 20 years ago, and even a few years ago appeared to be little more than a "space taxi" to ferry astronauts to and from the International Space Station.


Reposted bycygenb0ckylem235astronomygroupalphabetscience

May 05 2011


Floating Gyroscopes Vindicate Einstein

Four superconducting ping-pong balls floating in space have just confirmed two key predictions of Einstein’s general relativity, physicists announced in a press conference May 4.

“We have completed this landmark experiment testing Einstein’s universe, and Einstein survives,” said physicist Francis Everitt of Stanford University, the principal investigator on NASA’s Gravity Probe B mission.

The probe, which launched in 2004, was designed to test the effect Earth’s gravity has on the space-time around it. According to Einstein, the Earth warps its local space-time like a bowling ball sitting on a trampoline, a phenomenon called the geodetic effect. This effect means that a circle of fabric with the Earth’s circumference, about 24,900 miles, would be pulled into a shallow cone with a circumference 1.1 inches shorter.

The Earth also swirls the nearby space-time around with it as it rotates, like water spiraling around a drain, in an effect called frame-dragging.

“Picture the Earth immersed in honey, and you can imagine the honey would be dragged around with it,” Everitt said. “That’s what happens to space-time. Earth actually drags space and time around with it.”

Both effects are minuscule — Einstein himself wrote that “their magnitude is so small that confirmation of them by lab experiments is not to be thought of.” But Gravity Probe B measured them both. The results will be published in Physical Review Letters.

The spacecraft orbited the Earth for 17 months carrying four ping-pong ball sized gyroscopes. The gyroscopes were made of fused quartz spheres, which hold the Guinness Book record for “most spherical man-made object.” The spheres were covered in a soft metal called niobium and cooled to the temperature of liquid helium.

At that temperature, niobium becomes superconducting, which means that electrons can flow forever without losing energy. When the spheres are set spinning, the circling electrons give rise to a little magnetic pointer.

In Newton’s universe, that pointer would point in the same direction forever as the spacecraft circled the Earth. But in Einstein’s universe, where Earth twists and tugs the space-time around it, the gyroscopes’ pointer was sent atilt at a sliver-thin angle. The north-south tilt measured the geodetic effect, and the east-west tilt measured frame-dragging.

The pointer shifted by just 6,000 milliarcseconds — the width of a human hair as seen from 10 miles away — over the course of a year, Everitt said. Despite the difficulty in detecting such a small tilt, the physicists were able to confirm the geodetic effect to an accuracy of 0.28 percent, and frame-dragging to within 20 percent.

Because general relativity describes the large-scale structure of the universe, the Gravity Probe B results could help improve physicists’ understanding of cosmic phenomena from black holes to gamma-ray bursts, Everitt says.

Gravity Probe B is one of the longest-running NASA projects ever. It started in 1963, before men walked on the moon. It took five decades to develop the technologies to build gyroscopes sensitive enough to see gravitational effects. In the meantime, those technologies found homes in a host of other NASA Earth-observing satellites, plus the Cosmic Background Explorer satellite, which measured the cosmic microwave background and provided Nobel Prize-winning evidence for the big bang.

Physicist Clifford Will of Washington University in St. Louis, head of the external review board for Gravity Probe B, called the research team’s efforts “heroic” and stressed the importance of testing fundamental theories of nature, not just taking them for granted.

“It is popular lore that Einstein was right, but no such book is ever completely closed in science,” he said. “While the result in this case does support Einstein, it didn’t have to.”

Image: An artist’s rendition of the way the Earth warps space-time, called the geodetic effect. NASA/Gravity Probe B

See Also:

Reposted fromSigalontech Sigalontech

April 29 2011

Play fullscreen
Voyager Humanity's Farthest Journey

// oA:nth

WWW NASA Sites of the mission:


more entries on oA:nth concerning the
2 Voyager Spacecraft Mission

Reposted fromastronomygroup astronomygroup

March 29 2010


February 03 2010


Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
2010 February 3

P/2010 A2: Unusual Asteroid Tail Implies Powerful Collision
Credit: NASA, ESA, D. Jewitt (UCLA)

Explanation: What is this strange object? First discovered on ground based LINEAR images on January 6, the object appeared unusual enough to investigate further with the Hubble Space Telescope last week. Pictured above, what Hubble saw indicates that P/2010 A2 is unlike any object ever seen before. At first glance, the object appears to have the tail of a comet. Close inspection, however, shows a 140-meter nucleus offset from the tail center, very unusual structure near the nucleus, and no discernable gas in the tail. Knowing that the object orbits in the asteroid belt between Mars and Jupiter, a preliminary hypothesis that appears to explain all of the known clues is that P/2010 A2 is the debris left over from a recent collision between two small asteroids. If true, the collision likely occurred at over 15,000 kilometers per hour -- five times the speed of a rifle bullet -- and liberated energy in excess of a nuclear bomb. Pressure from sunlight would then spread out the debris into a trailing tail. Future study of P/2010 A2 may better indicate the nature of the progenitor collision and may help humanity better understand the early years of our Solar System, when many similar collisions occurred.

Reposted fromcypher cypher
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