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 then a kind of electromagnetic wave called Whistlers does the final job to kick them up to such intense speeds.


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.

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.


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.


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.


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 from ALESS65 as observed by the Australia Telescope Compact Array. Credit: Huynh et al.


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 the central supermassive black holes.


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 some supernovas (exploding stars) that emit gamma rays bursts.


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.


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.