nasa.gov: Comet Lovejoy Plunges into the Sun and Survives
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.
skyandtelescope.com: Asteroid To Buzz Earth Monday, June 27th
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.
io9.com: Earth may soon have a second sun
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 🙁
slashdot.org: NASA’s Kepler Spots Its First Rocky Exoplanet
“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.
slashdot.org: The Moon Has a Fluid Outer Core
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
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.
Cosmic Variance : Farewell, Pioneer Anomaly?
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.”