The new result comes from what’s called microlensing.

This kind of event takes an extraordinarily precise alignment, so they’re extremely rare. To compensate, you need to look at a lot of stars. So astronomers did: a survey using two telescopes covered several million stars every night, looking for the tell-tale bump(s). Over the course of six years, they found three — yes, only three — planets orbiting other stars acting like wee distant lenses. But that number is actually pretty good: when combined with previous surveys, and also taking into account how many lenses they didn’t see (which is important, statistically), they can extrapolate with some confidence about the numbers and types of exoplanets out there.

Via: slashdot.org: Comet Lovejoy Plunges Into the Sun and Survives

“It’s absolutely astounding,” says Karl Battams of the Naval Research Lab in Washington DC. “I did not think the comet’s icy core was big enough to survive plunging through the several million degree solar corona for close to an hour, but Comet Lovejoy is still with us.”

The most dramatic footage so far comes from SDO, which saw the comet go in (movie) and then come back out again (movie).

Comet Lovejoy was discovered on Dec. 2, 2011, by amateur astronomer Terry Lovejoy of Australia. Researchers quickly realized that the new find was a member of the Kreutz family of sungrazing comets. Named after the German astronomer Heinrich Kreutz, who first studied them, Kreutz sungrazers are fragments of a single giant comet that broke apart back in the 12th century (probably the Great Comet of 1106). Kreutz sungrazers are typically small (~10 meters wide) and numerous. The Solar and Heliospheric Observatory sees one falling into the sun every few days.

Full rotation of Jupiter from Jean-Luc Dauvergne on Vimeo.

Via: slashdot.org: Asteroid To Pass Near Earth On Monday

Asteroid 2011 MD, a chunk of rock estimated to be 25 to 55 feet (8 to 18 m) across, is expected to pass less than 8,000 miles above Earth’s surface around 1 p.m. EDT (17:00 UT) on Monday, June 27th. The actual event will be observable only from South Africa and parts of Antarctica, but the approach will be visible across Australia, New Zealand, southern and eastern Asia, and the western Pacific.

Via: Earth may soon have a second sun

The star is located in the Orion constellation, about 640 light-years away from Earth. It’s one of the brightest and biggest stars in our galactic neighborhood – if you dropped it in our Solar System, it would extend all the way out to Jupiter, leaving Earth completely engulfed. In stellar terms, it’s predicted to explode in the very near future. Of course, the conversion from stellar to human terms is pretty extreme, as Betelgeuse is predicted to explode anytime in the next million years.

J’aimerais bien voir ca de mon vivant, a condition qu’on ne soit pas directement alignes sur un des poles Mais disons que les chances sont assez minces avec l’horizon de un million d’annees

“NASA today said its star-gazing satellite Kepler has identified its first rocky planet orbiting a sun similar to our own — 560 light years from our solar system. While not in an area of space considered habitable, the rocky planet known as Kepler-10b is never-the-less significant because it showcases the ability of Kepler to find and track such small exoplanetary movements.

The new research confirms the existence of a solid inner core and liquid outer layer, similar to Earth’s. Unlike Earth, the moon also has a partly melted, mushy layer over that.

Seismic Detection of the Lunar Core

Abstract:
Despite recent insight regarding the history and current state of the Moon from satellite sensing and analyses of limited Apollo-era seismic data, deficiencies remain in our understanding of the deep lunar interior. We reanalyzed Apollo lunar seismograms using array processing methods to search for the presence of reflected and converted seismic energy from the core. Our results suggest the presence of a solid inner and fluid outer core, overlain by a partially molten boundary layer. The relative sizes of the inner and outer core suggest that the core is ~60% liquid by volume. Based on phase diagrams of iron alloys and the presence of partial melt, the core likely contains less than 6 weight % of lighter alloying components, which is consistent with a volatile-depleted interior.

Five years have passed. Using the telemetry data, the two scientists created an extremely elaborate “finite element” 3-D computer model of each Pioneer spacecraft, in which the thermal properties of 100,000 positions on their surfaces are independently tracked for the duration of the 30-year mission.

But according to Toth, “You can take it to the bank that whatever remains of the anomaly after accounting for that thermal acceleration, it will at most be much less than the canonical value of 8.74 x 10-10 m/s2, and then, mind you, all those wonderful numerical coincidences people talk about are destroyed.”

J’ai trouve cette version du video avec une trame sonore differente (who cares ) et la possibilite de le regarde en HD 1080p.

Plusieurs choses interessantes. Dans un premier temps, l’explosion du nombre d’asteroides decouverts dans les dernieres annees. Ensuite, le nombre d’asteroides (rouges dans le video) qui croisent l’orbite terrestre. Finalement, avec d’aussi grands nombres, rien de mieux qu’une representation graphique pour realiser combien il peut y en avoir! Et dire que le premier a ete decouvert seulement en 1801 et que seulement 15 avaient ete decouverts a la fin de 1851.

wikipedia.org : Asteroid

Explanation: A new comet is brightening and is now expected to become visible to the unaided eye later this month. C/2009 R1 (McNaught) is already showing an impressive tail and is currently visible through binoculars. The above image, taken yesterday from the Altamira Observatory in the Canary Islands and spanning about five degrees, shows an impressive green coma and a long ion tail in front of distant star trails. Although predicting the brightness of comets is notoriously difficult, current estimates place Comet McNaught as becoming visible to unaided northern hemisphere observers in late June, before sunrise, and in early July, after sunset. Discovered by Robert McNaught last year, the sun-orbiting iceberg will pass the Earth next week and will continue to melt and shed debris as it closes in on the Sun until early July. After reaching about half of the Earth-Sun distance from the Sun, the comet should fade rapidly as it then heads out of the inner Solar System.

Explanation: Goodbye Earth. Earlier this month, ESA’s interplanetary Rosetta spacecraft zoomed past the Earth on its way back across the Solar System. Pictured above, Earth showed a bright crescent phase featuring the South Pole to the passing rocket ship. Launched from Earth in 2004, Rosetta used the gravity of the Earth to help propel it out past Mars and toward a 2014 rendezvous with Comet Churyumov-Gerasimenko. Last year, the robot spacecraft passed asteroid 2867 Steins, and next year it is scheduled to pass enigmatic asteroid 21 Lutetia. If all goes well, Rosetta will release a probe that will land on the 15-km diameter comet in 2014.

In that case, we could imagine that the central star (presumably holding the disk together) could clear out a region near the center, and light passing through that hole could account for the brightening. I wrote a simple computer program (QuickBASIC on an IBM PC!) to calculate the light curve in this model, and we were able to get an extremely good fit to the data.

But technology has advanced quite a bit since my student years. Nowadays, we don’t need to puzzle out the meaning of a light curve and come up with an elaborate story involving tilted disks; we can just take pictures of the thing.

pbs.org: Hate Mail from Third Graders pour lire quelques-unes des lettres.

Tire de wikipedia.org: Synchronous rotation:

The Moon is in synchronous rotation about the Earth. In fact, most major moons in the solar system have synchronous rotation due to tidal locking.

Explanation: Even from the top of a volcanic crater, this vista was unusual. For one reason, Mars was dazzlingly bright two weeks ago, when this picture was taken, as it was nearing its brightest time of the entire year. Mars, on the far upper left, is the brightest object in the above picture. The brightness of the red planet peaked last week near when Mars reached opposition, the time when Earth and Mars are closest together in their orbits. Arching across the lower part of the image is a rare lunar fog bow. Unlike a more commonly seen rainbow, which is created by sunlight reflected prismatically by falling rain, this fog bow was created by moonlight reflected by the small water drops that compose fog. Although most fog bows appear white, all of the colors of the rainbow were somehow visible here. The above image was taken from high atop Haleakala, a huge volcano in Hawaii, USA.

Explanation: Eclipses are everywhere in this shady scene. The picture was taken on the Indian Ocean atoll island of Ellaidhoo, Maldives, on January 15, during the longest annular solar eclipse for the next 1,000 years. Tall palm trees provided the shade. Their many crossed leaves created gaps that acted like pinhole cameras, scattering recognizable eclipse images across the white sands of a tropical garden near the beach. From this idyllic location near the centerline of the Moon’s shadow track, the ring of fire or annular phase of the eclipse lasted about 10 minutes and 55 seconds.

Explanation: The ancient text has no known title, no known author, and is written in no known language: what does it say and why does it have many astronomy illustrations? The mysterious book was once bought by an emperor, forgotten on a library shelf, sold for thousands of dollars, and later donated to Yale. Possibly written in the 15th century, the over 200-page volume is known most recently as the Voynich Manuscript, after its (re-)discoverer in 1912. Pictured above is an illustration from the book that appears to be somehow related to the Sun. The book labels some patches of the sky with unfamiliar constellations. The inability of modern historians of astronomy to understand the origins of these constellations is perhaps dwarfed by the inability of modern code-breakers to understand the book’s text. Can the eclectic brain trust of APOD readers make any progress? If you think you can provide any insight, instead of sending us email please participate in a fresh online discussion. The book itself remains in Yale’s rare book collection under catalog number “MS 408.”

Explanation: They might look like trees on Mars, but they’re not. Groups of dark brown streaks have been photographed by the Mars Reconnaissance Orbiter on melting pinkish sand dunes covered with light frost. The above image was taken in 2008 April near the North Pole of Mars. At that time, dark sand on the interior of Martian sand dunes became more and more visible as the spring Sun melted the lighter carbon dioxide ice. When occurring near the top of a dune, dark sand may cascade down the dune leaving dark surface streaks — streaks that might appear at first to be trees standing in front of the lighter regions, but cast no shadows. Objects about 25 centimeters across are resolved on this image spanning about one kilometer. Close ups of some parts of this image show billowing plumes indicating that the sand slides were occurring even when the image was being taken.

Explanation: Every 27 years Epsilon Aurigae fades, remaining dim for roughly two years before growing bright again. Since the 19th century, astronomers have studied the mystery star, eventually arguing that Epsilon Aur, centered in this telescopic skyview, was actually undergoing a long eclipse by a dark companion object. But the nature of the companion and even the state of bright star itself could not be pinned down by observations. Continuing to collect evidence, Citizen Sky, a team of professional and amateur astronomers, is studying the current eclipse of Epsilon Aur, reporting that it began in August 2009 and by late December had reached its deepest point. Epsilon Aur is now expected to remain dim for all of 2010, before rapidly regaining normal brightness in 2011. Meanwhile, recent infrared data from the Spitzer Space Telescope supports a model for the enigmatic system that identifies Epsilon Aur as a large but lower mass star near the end of its life, periodically eclipsed by a single star embedded in a dusty disk. The disk is estimated to have a radius of about 4 AU, or 4 times the Earth-Sun distance, and to be about 0.5 AU thick.

Via: Planetary Systems Now Forming in Orion

Explanation: How do planets form? To help find out, the Hubble Space Telescope was tasked to take a detailed look at one of the more interesting of all astronomical nebulae, the Great Nebula in Orion. The Orion nebula, visible with the unaided eye near the belt in the constellation of Orion, is an immense nearby starbirth region and probably the most famous of all astronomical nebulas. Insets to the above mosaic show numerous proplyds, many of which are stellar nurseries likely harboring planetary systems in formation. Some proplyds glow as close disks surrounding bright stars light up, while other proplyds contain disks further from their host star, contain cooler dust, and hence appear as dark silhouettes against brighter gas. Studying this dust, in particular, is giving insight for how planets are forming. Many proplyd images also show arcs that are shock waves – fronts where fast moving material encounters slow moving gas. The Orion Nebula lies about 1,500 light years distant and is located in the same spiral arm of our Galaxy as our Sun.