Space

What creates the two gigantic donuts of radiation surrounding Earth called the Van Allen radiation belts? The Van Allen Probes launched in 2012 want to find out. The inner Van Allen radiation belt is fairly stable, but the outer one changes shape, size and composition in ways that scientists don't yet perfectly understand. Some of the particles within this belt zoom along at close to light speed, but just what accelerates these particles up to such velocities? Recent data from the Van Allen Probes suggests that it is a two-fold process: One mechanism gives the particles an initial boost and…

Sometimes we have to wonder in amazement about things found out in the universe. Case in point: a slinky string of pearls twisted into a corkscrew shape. Nothing special about that. Except this string is 100,000 light years long. The pearls in the string are superclusters of blazing, blue-white, newly born stars and the structure forms a bridge between two giant elliptical galaxies that are colliding. These young, blue "super star clusters" are evenly spaced along the chain at separations of 3,000 light-years from one another. The pair of elliptical galaxies is embedded deep inside the…

As every Boy Scout knows, friction generates heat. A new study finds that friction could be the key to survival for some distant Earth-sized planets traveling in dangerous orbits. Earth-sized planets are becoming common in other star systems. Too close to a star, and heat can be a destructive force but for planets in the habitable zone, the right amount of friction, and therefore heat, can be helpful and perhaps create conditions for habitability. "We found some unexpected good news for planets in vulnerable orbits," said Wade Henning, a University of Maryland scientist working at NASA's…

Olber's Paradox asks why the sky is not a sheet of white. Since just the galaxy we are in has 50 stars for every person currently on earth traveling to us at all time, how can it ever get dark when there are billions of galaxies all containing stars?  It isn't just a visible light mystery, something is amiss in the ultraviolet Universe also.  We can't explain all of the light in the cosmic budget. The vast reaches of empty space between galaxies are bridged by tendrils of hydrogen and helium, which can be used as a precise "light meter." In a recent study, a team of…

Planet Mercury's metal-rich composition is a puzzle in planetary science. According to a new simulation, Mercury and other unusually metal-rich objects in the solar system may be relics left behind by collisions in the early solar system that built the other planets. The origin of Mercury has been a difficult question in planetary science because its composition is very different from other planets and the moon. It is so different it's a wonder that the 2 percent of the astronomers in the International Astronomical Union haven't tried to Pluto it also. This small, innermost object has more…

Astronomers have studied the carbon monoxide in ALESS65, a galaxy over 12 billion light years away, and found that it's literally running out of gas. The future is not dark, it's 'red and dead'. ALESS65 was observed by the Atacama Large Millimeter Array (ALMA) in 2011 and is one of few known distant galaxies to contain carbon monoxide.  While our galaxy, the Milky Way, has about 5 billion years before it runs out of fuel and becomes 'red and dead', ALESS65 is a gas guzzler and only has 10s of millions of years left – that is very rapid, in astronomical terms.  Radio waves emitted…

Supermassive black holes in the cores of some galaxies drive massive outflows of molecular hydrogen gas. As a result, most of the cold gas is expelled from the galaxies. Since cold gas is required to form new stars, this directly affects the galaxies' evolution and those outflows are a key ingredient in theoretical models of the evolution of galaxies, but it is a mystery how they are accelerated. A new study provides the first direct evidence that the molecular outflows are accelerated by energetic jets of electrons that are moving at close to the speed of light. Such jets are propelled by…

Astronomers have found a "hotspot" beneath the Big Dipper emitting a disproportionate number of the highest-energy cosmic rays, a discovery which may move physics toward identifying the mysterious sources of the most energetic particles in the universe. Many astrophysicists suspect ultrahigh-energy cosmic rays are generated by active galactic nuclei, or AGNs, in which material is sucked into a supermassive black hole at the center of galaxy, while other material is spewed away in a beam-like jet known as a blazar. Another popular possibility is that the highest-energy cosmic rays come from…

A newly discovered planet now named OGLE-2013-BLG-0341LBb in a binary star system located 3,000 light-years from Earth is expanding astronomers' notions of where Earth-like—and even potentially habitable—planets can form. And how to find them. At twice the mass of Earth, the planet orbits one of the stars in the binary system at almost exactly the same distance from which Earth orbits the sun. However, because the planet's host star is much dimmer than the sun, the planet is much colder than the Earth—a little colder, in fact, than Jupiter's icy moon Europa. The study provides the first…

Astronomers search for exoplanets by measuring shifts in the pattern of a star's spectrum - the different wavelengths of radiation that it emits as light. These "Doppler shifts" result from subtle changes in the star's velocity caused by the gravitational tugs of orbiting planets, but Doppler shifts of a star's absorption lines can also result from magnetic events like sunspots originating within the star itself -- giving false clues of a planet that does not actually exist. "In the search for low-mass planets,"  said Suvrath Mahadevan, an assistant professor of astronomy and…