The super-massive black hole at the center of the Milky Way Galaxy has a healthy appetite, frequently snacking on asteroids and comets. Now, a cloud of gas and dust called G2 is on a dangerous course to become its next meal.
Even though Sagittarius A* (pronounced “Sagittarius A-star”) hasn’t been easy to see through the cosmic dust, sitting 25,000 light years away at galaxy central, scientists know it is a black hole — and a hungry one at that. Its weight has been estimated to be more than that of 4 million suns. (more…)
President Obama designated October as National Cyber Security Awareness Month. We asked John E. Savage, the An Wang Professor of Computer Science, to share his views on what can and should be done to ensure cybersecurity at the national level. Savage is active in cybersecurity from both a policy and technology point of view, having spent the 2009-10 academic year in the U.S. Department of State as a Jefferson Science Fellow.
In a major policy speech delivered last week, Secretary of Defense Leon Panetta sparked a new discussion of cyberwarfare threats, warning that cyberattacks “could virtually paralyze the nation.” The three-part response Panetta outlined emphasizes new cyberwarfare capabilities in the Department of Defense, new policies and organizations across the federal government, and stronger partnerships between the government and international partners and domestic industry. (more…)
A study of 544 star-forming galaxies shows that disk galaxies like our own Milky Way reached their current state as orderly rotating pinwheels much later than previously thought, long after much of the universe’s star formation had ceased.
Galaxies are in no hurry to grow up, a team of astronomers has discovered. A comprehensive study of hundreds of galaxies observed by the Keck telescopes in Hawaii and NASA’s Hubble Space Telescope has revealed an unexpected pattern of change that extends back 8 billion years, or more than half the age of the universe.
Researchers say the distant blue galaxies they studied are gradually transforming into rotating disk galaxies like our own Milky Way. Until now, it had not been clear how a galaxy’s organization and internal motion change over time, said Benjamin Weiner, assistant astronomer at the UA Steward Observatory and co-author of the paper describing the findings, which are published in The Astrophysical Journal. (more…)
ANN ARBOR, Mich.— The fastest wind ever discovered blowing off a disk around a stellar-mass black hole has been observed by a team of astronomers that includes a University of Michigan doctoral student.
Using NASA’s Chandra X-ray Observatory, an orbiting telescope, they clocked the record-breaking super wind at about 20 million mph, or about 3 percent of the speed of light. This is nearly 10 times faster than astronomers had previously observed from a stellar-mass black hole. (more…)
WASHINGTON, D.C. — Measurable improvements in air quality and visibility, human health, and water quality in many acid-sensitive lakes and streams, have been achieved through emissions reductions from electric generating power plants and resulting decreases in acid rain. These are some of the key findings in a report to Congress by the National Acid Precipitation Assessment Program, a cooperative federal program.
The report shows that since the establishment of the Acid Rain Program, under Title IV of the 1990 Clean Air Act Amendments, there have been substantial reductions in sulfur dioxide (SO2) and nitrogen oxides (NOx) emissions from power plants that use fossil fuels like coal, gas and oil, which are known to be the primary causes of acid rain. As of 2009, emissions of SO2 and NOx declined by about two-thirds relative to levels in the 1990s. These emissions levels declined even further in 2010, according to recent data compiled by the U.S. Environmental Protection Agency. (more…)
A circular rainbow appears like a halo around an exploded star in this new view of the IC 443 nebula from NASA’s Wide-field Infrared Survey Explorer, or WISE.
When massive stars die, they explode in tremendous blasts, called supernovae, which send out shock waves. The shock waves sweep up and heat surrounding gas and dust, creating supernova remnants like the one pictured here. The supernova in IC 443 happened somewhere between 5,000 and 10,000 years ago. (more…)
Fireworks. Downtown Miami on July 4, 2007. Image credit: Marc Averette. Source: Wikipedia
Fireworks can be spectacular. However, the gas and smoke produced by the colorful explosions carry extremely high levels of toxic particles, according to a study by Audrey Smargiassi, a professor at the Université de Montreal Department of Environmental and Occupational Health.
Smargiassi conducted one of the first studies examining the composition of the emitted gases and the concentration of the particles. In addition, her study is unique as she collected her data below the fireworks display where spectators usually stand. Previous studies usually collected data from nearby rooftops.
The study was conducted in 2007 during nine separate shows presented at La Ronde amusement park where 5.7 million spectators attend an international fireworks competition every summer. (more…)
The Earth is constantly manufacturing new crust, spewing molten magma up along undersea ridges at the boundaries of tectonic plates. The process is critical to the planet’s metabolism, including the cycle of underwater life and the delicate balance of carbon in the ocean and atmosphere.
Now, scientists at the Woods Hole Oceanographic Institution (WHOI) have observed ocean crust forming in an entirely unexpected way—one that may influence those cycles of life and carbon and, in turn, affect the much-discussed future of the world’s climate.
Working at the Guaymas basin in the Gulf of California, WHOI scientists confirmed what they suspected from brief glimpses of the area during previous missions: The inner Earth is injecting swaths of magma called sills as far as 50 kilometers away from the plate boundary, on each side of the ridge —nearly 10 times farther from such an active ocean ridge than had been observed before.(more…)
