Physics & Astronomy News

<p>Artist rendering<br />
New radiation source could be less harmful alternative to x-rays
A new source of intense terahertz (THz) radiation, which could offer a less harmful alternative to x-rays and has strong potential for use in industry, is being developed.
<p>Though Mercury may look drab to the human eye, different minerals appear in a rainbow of colors in this image from NASA's MESSENGER spacecraft. (Image credit: NASA/Johns Hopkins University APL/Carnegie Institution of Washington)</p>
Mercury May Have a Thinner Crust Than We Thought
Scientists used careful mathematical calculations to determine the density of Mercury’s crust, which is thinner than anyone thought.

<p>An artistic view of frequency conversion from near-infrared to mid-infrared through a nonlinear crystal. (Photo: Alexander Gelin)</p>
Molecules Brilliantly Illuminated
A new high-power laser system generates ultrashort pulses of light covering a large share of the mid-infrared spectrum.
<p>A cloud of atoms is held above a chip by electromagnetic fields. The EPR paradox was observed between the spatially separated regions A and B (Illustration: University of Basel, Department of Physics)</p>
EPR paradox observed in many-particle system for the first time
Physicists have observed the quantum mechanical Einstein-Podolsky-Rosen paradox in a system of several hundred interacting atoms for the first time.

Einstein’s “spooky action” goes massive!
The elusive quantum mechanical phenomenon called entanglement has now been made a reality in objects almost macroscopic in size.
Organic solar cells reach record efficiency
In an advance that makes a more flexible, inexpensive type of solar cell commercially viable, researchers have demonstrated organic solar cells that can achieve 15% efficiency.
New exotic phenomena seen in photonic crystals
Researchers observe, for the first time, topological effects unique to an 'open' system.

Science Facts

Stars With Long Hair

by NASA Headquarters and

Comet Borrelly as Seen By Deep Space 1: Image Courtesy NASA Throughout history, people have been both awed and alarmed by comets, stars with 'long hair' that appeared in the sky unannounced and unpredictably. We now know that comets are dirty-ice leftovers from the formation of our solar system around 4.6 billion years ago. They are among the least-changed objects in our solar system and, as such, may yield important clues about the formation of our solar system. We can predict the orbits of many of them, but not all. Around a dozen 'new' comets are discovered each year.

Each comet has only a tiny solid part, called a nucleus, often no bigger than a few kilometers across. The nucleus contains icy chunks and frozen gases with bits of embedded rock and dust. At its center, the nucleus may have a small, rocky core. As a comet nears the Sun, it begins to warm up. The comet gets bright enough to see from Earth while its atmosphere - the coma - grows larger. The Sun's heat causes ice on the comet's surface to change to gases, which fluoresce like a neon sign. 'Vents' on the Sun-warmed side may release fountains of dust and gas for tens of thousands of kilometers. The escaping material forms a coma that may be hundreds of thousands of kilometers in diameter.

The pressure of sunlight and the flow of electrically charged particles, called the solar wind, blow the coma materials away from the Sun, forming the comet's long, bright tails, which are often seen separately as straight tails of electrically charged ions and an arching tail of dust. The tails of a comet always point away from the Sun. Most comets travel a safe distance from the Sun itself. Comet Halley comes no closer than 89 million kilometers from the Sun, which is closer to the Sun than Earth is. However, some comets, called sun-grazers, crash straight into the Sun or get so close that they break up and vaporize. Impacts from comets played a major role in the evolution of the Earth, primarily during its early history billions of years ago. Some believe that they brought water and a variety of organic molecules to Earth.

Using infrared technology, NASA
Nursery of Giants Captured in New Spitzer Image

Typically, the bigger something is the easier it is to find. Elephants, for example, are not hard to spot. But when it comes to the massive stars making up the stellar nursery called DR21, size does n ...
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Candy that glows?
Can Wint-O-Green Lifesavers® Light up Your Life?

Next time you're bored, grab a pack of Wint-O-Green Lifesavers® and lock yourself in the bathroom. Shut the blinds and make sure the room is pitch black. Allow your eyes to adjust and open the pack ...
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A Satellite Of Our Own

The regular daily and monthly rhythms of Earth's only natural satellite, the Moon, have guided timekeepers for thousands of years. Its influence on Earth's cycles, notably tides, has also been charted ...
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Science Quote

'Science is a refinement of everyday thinking.'

Albert Einstein

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