Just over 1,200 years ago, the planet was hit by an extremely intense burst of high-energy radiation of unknown cause, scientists studying tree-ring data have found.

The radiation burst, which seems to have hit between ad 774 and ad 775, was detected by looking at the amounts of the radioactive isotope carbon-14 in tree rings that formed during the ad 775 growing season in the Northern Hemisphere. The increase in ¹⁴C levels is so clear that the scientists, led by Fusa Miyake, a cosmic-ray physicist from Nagoya University in Japan, conclude that the atmospheric level of ¹⁴C must have jumped by 1.2% over the course of no longer than a year, about 20 times more than the normal rate of variation. Their study is published online in Nature today¹.

"The work looks pretty solid," says Daniel Baker, a space physicist at the University of Colorado's Laboratory for Atmospheric and Space Physics in Boulder, Colorado. "Some very energetic event occurred in about ad 775."

Exactly what that event was, however, is more difficult to determine.

The ¹⁴C isotope is formed when highly energetic radiation from outer space hits atoms in the upper atmosphere, producing neutrons. These collide with nitrogen-14, which then decays to ¹⁴C. (The fact that this is always happening because of background radiation is what produces a continuous source of ¹⁴C for radiocarbon dating.)

SETI astronomers have eavesdropped on an alien star system thought to contain two "habitable" worlds in the hope of hearing a radio transmission from an extraterrestrial intelligence.

Sadly, there appears to be no chatty aliens living around the red dwarf star Gliese 581.

In results announced last week by Australian SETI astronomers, of the International Centre for Radio Astronomy Research at Curtin University in Perth, Gliese 581 was precisely targeted by Australian Long Baseline Array using three radio telescope facilities across Australia. This is the first time the technique of very long baseline interferometry (VLBI) has been used to target a specific star in the hunt for extraterrestrials, so although it didn't turn up any aliens, it is a proof of concept that may prove invaluable for future SETI projects.

The Gliese 581 system, located 20 light-years from Earth, has been the focus for intense exoplanetary studies. It is thought to play host to at least six exoplanets, two of which orbit the star within the star's "habitable zone." This zone is the distance from a star where it's not too hot and not too cold for water to exist in a liquid state on a hypothetical rocky world's surface.

As this is a red dwarf star, it is smaller, dimmer and therefore cooler than our sun. As a result, the Gliese 581 habitable zone is a lot more compact than our sun's. Gliese 581d -- a "super-Earth" with a mass seven times that of our planet -- skirts the outermost edge of the Gliese 581 habitable zone and has an orbital period of only 67 days. Gleise 581g on the other hand is thought to be around three-times the mass of Earth and orbits right in the middle of the star's habitable zone. Its orbital period has been clocked at 37 days. (It is worth noting, however, the very existence of Gliese 581g has been called into question.)

Naturally, the mere hint of these "habitable" worlds in Gliese 581 has caused some excitement -- they could host the perfect conditions for life (as we know it) to thrive. If there's life, then perhaps it evolved to support intelligence; if there's intelligence, then perhaps it has gone through a similar "radio transmitting" phase as us.

When Venus interposes itself directly between Earth and the sun for the last time in more than a century, national parks across America will be prepared to observe the historic event. Many will have special filtered telescopes set up for safe viewing of the sun, while rangers stand by to answer questions.

Every national park within the United States should be able to view the transit of Venus, either completely or in part, in the hours leading up to sunset on Tuesday, June 5.

The duration of the transit varies depending on how long before sunset it begins in a particular location. The eastern United States only has two prime hours to view Venus' rare trip before the sun goes down, while Hawaii and Alaska are primed to watch the entire six-and-a-half hour crossing.

Of course, you should never look directly at the sun, or stare at it through an unprotected telescope or camera. Many parks will have solar glasses available to allow visitors to safely observe the transit, and their telescopes will be specially outfitted with solar filters.

© Uniquely India/Getty ImagesThe U.S. continues to flirt with the idea of a ‘human barcode,’ an electronic ID chip assigned to every person at birth.

As tech companies work to develop ID chips, how long until we're no longer anonymous?

Would you barcode your baby?

Microchip implants have become standard practice for our pets, but have been a tougher sell when it comes to the idea of putting them in people.

Science fiction author Elizabeth Moon last week rekindled the debate on whether it's a good idea to "barcode" infants at birth in an interview on a BBC radio program.

"I would insist on every individual having a unique ID permanently attached - a barcode if you will - an implanted chip to provide an easy, fast inexpensive way to identify individuals," she said on The Forum, a weekly show that features "a global thinking" discussing a "radical, inspiring or controversial idea" for 60 seconds .

Recent findings from NASA's Cassini mission reveal that Saturn's geyser moon Enceladus provides a special laboratory for watching unusual behavior of plasma, or hot ionized gas. In these recent findings, some Cassini scientists think they have observed "dusty plasma," a condition theorized but not previously observed on site, near Enceladus.

Data from Cassini's fields and particles instruments also show that the usual "heavy" and "light" species of charged particles in normal plasma are actually reversed near the plume spraying from the moon's south polar region. The findings are discussed in two recent papers in the Journal of Geophysical Research.

Systems that can identify emotions in images of faces might soon collate millions of peoples' reactions to events and could even replace opinion polls

IF THE computers we stare at all day could read our faces, they would probably know us better than anyone.

That vision may not be so far off. Researchers at the Massachusetts Institute of Technology's Media Lab are developing software that can read the feelings behind facial expressions. In some cases, the computers outperform people. The software could lead to empathetic devices and is being used to evaluate and develop better adverts.

But the commercial uses are just "the low-hanging fruit", says Rana el Kaliouby, a member of the Media Lab's Affective Computing group. The software is getting so good and so easy to use that it could collate millions of peoples' reactions to an event as they sit watching it at home, potentially replacing opinion polls, influencing elections and perhaps fuelling revolutions.

Cbet Circular No. 3132, issued on 2012, May 31, announces the recovery of comet P/1994 X1 = 2012 K7 (McNaught-Russell) by our team; this comet was discovered on 1994, December 12 with the UK Schmidt Telescope at Siding Spring observatory and it was last observed on 1995, April 17.

On 2012, May 29 we started an observing session to recover the periodic comet P/1994 X1. We found an object of magnitude ~19.5 located ~35 arcsec south-west of the nominal position, along the line of variations (LOV). Stacking of 7 R-filtered exposures, 60-sec each, obtained remotely, from the Haleakala-Faulkes Telescope North on 2012, May 29.6, through a 2.0-m f/10.0 Ritchey-Chretien + CCD, under good seeing conditions, shows that comet P/1994 X1 appears slightly diffuse, with a tiny coma about 3" in diameter, having a total m1 magnitude measured through a Bessel-R filter of about 19.5.

Second night follow-up observations, has been obtained on 2012, May 30.4, under the code H06. Stacking of 8 unfiltered exposures, 180-sec each, obtained on 2012, May 30.4 remotely from the ITelescope network near Mayhill, NM, through a 0.43-m f/6.8 astrograph + CCD + f/4.5 focal reducer, shows that this comet has a nearly stellar appearance.

Lying about eating your fruits and vegetables won't save you when facing the unflinching gaze of a blue laser beam. That's because shining a blue laser light on human skin can detect biomarkers that tell whether fruits and vegetables figure into a person's diet, researchers say.

The simple method works by revealing carotenoid pigments such as beta-carotene in carrots and lycopene in tomatoes.

A modern version of a decades-old technology called resonance Raman spectroscopy (RRS) can detect the energy changes in molecules after being energized by the laser light - a painless process that returns results in about a minute.

"It really derived from an observation that people have known about for decades," said Susan Mayne, head of chronic disease epidemiology at Yale University, "and that is that when people have high-vegetable diets they develop a yellow skin coloration that is particularly noticeable in the palm of the hand because of the accumulation of carotenoids in the skin."

"And we thought, 'Can we use that as a new approach to measure carotenoids in the body noninvasively?'"

Two of the heaviest elements on the periodic table were officially named on Thursday (May 31).

The man-made elements 114 and 116, which contain 114 and 116 protons per atom, respectively, are now officially called flerovium (Fl) and livermorium (Lv).

The names were chosen to honor the laboratories that first created the elements: the Flerov Laboratory of Nuclear Reactions in Dubna, Russia, and Lawrence Livermore National Laboratory in Livermore, Calif.

Scientists at the two institutions collaborated to synthesize both of these heavy elements by smashing calcium, which has 20 protons, into curium, which contains 96 protons. When these atomic nuclei collided (the electrons were stripped off beforehand, rendering the atoms into ions), they glommed together to create element 116.

Such large "super-heavy" elements are not stable, so element 116 decayed almost immediately into element 114. In separate trials, the researchers created 114 independently by slamming together calcium and plutonium, which has 94 protons.

The elements were first made more than 10 years ago, but subsequent testing was required to confirm the fleeting elements' existence. The elements' official names were not approved until now by the International Union of Pure and Applied Chemistry (IUPAC), which governs chemical nomenclature.

Long before babies understand the story of Goldilocks, they have more than mastered the fairy tale heroine's method of decision-making. Infants ignore information that is too simple or too complex, focusing instead on situations that are "just right," according to a new study to be published in the journal PLoS ONE on May 23. Dubbed the "Goldilocks effect" by the University of Rochester team that discovered it, the attention pattern sheds light on how babies learn to make sense of a world full of complex sights, sounds, and movements. The findings could have broad implications for human learning at all ages and could lead to tools for earlier diagnosis of attention-related disabilities such as ADHD or autism, says Celeste Kidd, lead author on the paper and a doctoral candidate in brain and cognitive sciences at the University.

With the aid of eye-tracking devices and statistical modeling, the research is the first to provide both a theory and quantifiable measures of what keeps a baby's attention, says coauthor Richard Aslin, the William R. Kenan Professor of brain and cognitive sciences at the University.