One of the closest galaxies to the Milky Way almost got away with theft. However, new simulations convicted the Large Magellanic Cloud (LMC) of stealing stars from its neighbor, the Small Magellanic Cloud (SMC). And the crucial evidence came from surveys looking for something entirely different – dark objects on the outskirts of the Milky Way.
Astronomers have been monitoring the LMC to hunt for evidence of massive compact halo objects, or MACHOs. MACHOs were thought to be faint objects, roughly the mass of a star, but their exact nature was unknown. Several surveys looked for MACHOs in order to find out if they could be a major component of dark matter – the unseen stuff that holds galaxies together.
“We originally set out to understand the evolution of the interacting LMC and SMC galaxies,” explains lead author Gurtina Besla of Columbia University. “We were surprised that, in addition, we could rule out the idea that dark matter is contained in MACHOs.” “Instead of MACHOs, a trail of stars removed from the SMC is responsible for the microlensing events,” says co-author Avi Loeb of the Harvard-Smithsonian Center for Astrophysics. “You could say we discovered a crime of galactic proportions,” he adds.
As they near the outer reaches of the solar system, for the past several years the two Voyager spacecraft have been sending back observations that challenge scientists’ views of the physics at the edge of the heliosphere, the bubble created by charged particles flowing outward from the Sun. A new study looks at magnetic field fluctuations and cosmic ray intensity observed by Voyager I.
In 2004, Voyager I crossed the termination shock, the region where the solar wind begins to slow as it interacts with the interstellar medium. Just outside the termination shock is the heliosheath, where the solar wind continues to slow, reaching a stagnation region where solar wind speed drops to zero. Burlaga and Ness studied the magnetic field observed by Voyager I during 2010, when the spacecraft was moving through this stagnation region. Their analysis shows that magnetic field fluctuations outside the termination shock were primarily compressive fluctuations in field strength along the direction of the motion of the planets around the Sun. The fluctuations were observed on time scales of several hours.
Using a brand-new radio telescope, astronomers have produced one of the best images ever made at the lowest frequencies of giant bubbles produced by a super-massive black hole. The observations were performed at frequencies ranging from 20 to 160 MHz which are normally used for communications by airplane pilots. The picture shows what looks like a giant balloon filled with radio emitting plasma, which exceeds the size of an entire galaxy.
Some black holes actively accrete matter. Part of this material does not fall into the black hole but is ejected in a narrow stream of particles, traveling at nearly the speed of light. When the stream slows down, it creates a tenuous balloon that can engulf the entire galaxy.
“The result is of great importance”, says Francesco de Gasperin, lead author of the study that will be published in the journal Astronomy & Astrophysics. “It shows the enormous potential of LOFAR, and provides compelling evidence of the close ties between black hole, host galaxy, and their surroundings. Like symbiotic species” adds de Gasperin, “a galaxy and its central black hole lead intimately connected lives, the galaxy providing matter to feed the black hole, and the black hole returning energy to the galaxy”.
International leaders in asteroid and comet research are gathering at the University of Central Florida in Orlando Friday, Feb. 15, for a special “viewing party” that will climax with asteroid 2012 DA14 zipping between Earth and orbiting communication satellites (within 14,000 miles of Earth). The asteroid, the size of a city block, will squeeze by Earth’s atmosphere and the geostationary satellites orbiting the planet. It will be the closest fly by in history.
Experts say there is no chance the asteroid will hit Earth — this time. But with more than 4,700 asteroids NASA has identified as potential threats to Earth, some as big as 16 football fields, these objects are getting a lot of attention. Should an asteroid be detected on a collision course with Earth, it will be critical to know its composition and structure in order to deflect it. The impact of a small asteroid like DA 14 would equal the destructive power of an atomic bomb. A larger asteroid could be catastrophic.
NASA has a new online science resource for teachers and students to help bring Earth, the solar system, and the universe into their schools and homes.
Called NASA Wavelength, the site features hundreds of resources organized by topic and audience level from elementary to college, and out-of-school programs that span the extent of NASA science. Educators at all levels can locate educational resources through information on educational standards, subjects and keywords and other relevant details, such as learning time required to carry out a lesson or an activity, cost of materials and more.
“NASA Wavelength not only lets users find nearly everything they want to know about NASA science, but it also allows them to provide direct feedback to NASA to enhance our products,” said Stephanie Stockman, education lead for NASA’s Science Mission Directorate (SMD) in Washington. “This truly is a living, digital library of resources that will allow educators to find and share the best of NASA science education resources to advance their teaching.”
Full Story: http://www.nasa.gov/home/hqnews/2012/oct/HQ_12-379_Online_Science_Resource.html
NASA Wavelength: http://nasawavelength.org/
Slooh will take visitors on a scary journey through the cosmos as we explore celestial objects that have been historically associated with spooky tales or outright fear. The live program will begin on Monday, 29 October 2012, at 4 p.m. PDT / 7 p.m. EDT / 23:00 UTC with real time views from Slooh’s Canary Islands observatory. The event is free to the public on Slooh.com and viewers can watch live on their PC or iOS/Android mobile device.
The Hunter’s Moon will be up that night — a perfect prelude to Halloween, since the Moon plays a rich role in Halloween lore. But, unknown to most of the public, other prominent celestial objects are even more deeply associated with “the darker side” of the night. Slooh will also observe and discuss the “Seven Sisters” or Pleiades star cluster, whose date of midnight culmination was the very origin of the original Black Sabbath, which evolved into All Hallows Eve and ultimately Halloween. Why was this beautiful blue cluster so associated with death and evil?
Slooh will examine these stories and more as we view the Hunter’s Moon live. Slooh’s Fright Night will be hosted by Slooh President Patrick Paolucci, who will be joined by Slooh Outreach Coordinator Paul Cox and Astronomy Magazine columnist Bob Berman.
Live Program: http://events.slooh.com/
Paintballs May Deflect An Incoming Asteroid: With 20 Years’ Notice, Paint Pellets Could Cause An Asteroid To Veer Off Course
In the event that a giant asteroid is headed toward Earth, you’d better hope that it’s blindingly white. A pale asteroid would reflect sunlight — and over time, this bouncing of photons off its surface could create enough of a force to push the asteroid off its course.
How might one encourage such a deflection? The answer, according to an MIT graduate student: with a volley or two of space-launched paintballs.
Sung Wook Paek, a graduate student in MIT’s Department of Aeronautics and Astronautics, says if timed just right, pellets full of paint powder, launched in two rounds from a spacecraft at relatively close distance, would cover the front and back of an asteroid, more than doubling its reflectivity, or albedo. The initial force from the pellets would bump an asteroid off course; over time, the sun’s photons would deflect the asteroid even more.