Climate change is exposing reindeer hunting gear used by the Vikings' ancestors faster than archaeologists can collect it from ice thawing in northern Europe's highest mountains.

"It's like a time machine...the ice has not been this small for many, many centuries," said Lars Piloe, a Danish scientist heading a team of "snow patch archaeologists" on newly bare ground 1,850 meters (6,070 ft) above sea level in mid-Norway.

Specialized hunting sticks, bows and arrows and even a 3,400-year-old leather shoe have been among finds since 2006 from a melt in the Jotunheimen mountains, the home of the "Ice Giants" of Norse mythology.

As water streams off the Juvfonna ice field, Piloe and two other archaeologists -- working in a science opening up due to climate change -- collect "scare sticks" they reckon were set up 1,500 years ago in rows to drive reindeer toward archers.

Called Atumpucro, it has some 150 circular homes and impressive walls. Seated on a hill of the same name, it was found in the province of Luya by photographer and explorer Martín Chumbe.

An archaeological complex full of typical Chachapoyan round builds has been discovered in the district of San Juan de Lopecancha, province de Luya in the Amazonas region. The discovery was made by local explorer and photographer Martín Chumbe in a joint expedition with the district's mayor, owner of the land.

The National Institute of Standards and Technology (NIST) has issued its first Guidelines for Smart Grid Cyber Security, which includes high-level security requirements, a framework for assessing risks, an evaluation of privacy issues at personal residences, and additional information for businesses and organizations to use as they craft strategies to protect the modernizing power grid from attacks, malicious code, cascading errors and other threats.

The product of two formal public reviews and the focus of numerous workshops and teleconferences over the past 17 months, the three-volume set of guidelines is intended to facilitate organization-specific Smart Grid cyber security strategies focused on prevention, detection, response and recovery.

The new report was prepared by the Cyber Security Working Group (CSWG) of the Smart Grid Interoperability Panel, a public-private partnership launched by NIST with American Recovery and Reinvestment Act funding from the Department of Energy. The guidelines are the second major output of NIST-coordinated efforts to identify and develop standards needed to convert the nation's aging electric grid into an advanced, digital infrastructure with two-way capabilities for communicating information, controlling equipment and distributing energy.

Our planet is a place rich in sound. This panoply of sound is so important to our perception of our world that when the Voyager spacecraft were launched as our ambassadors to the universe, a collection of sounds from Earth were part of what they took with them. Along with images and other information about Earth and humankind, there were recordings (on very old-fashioned analog disks) of the sounds of natural phenomena such as wind, surf, and thunder. There were also animal sounds, music from many cultures, and spoken greetings in several dozen languages, including a clip from then-President Jimmy Carter.

Though it was once believed that all asteroids are giant pieces of solid rock, later hypotheses have it that some are actually a collection of small gravel-sized rocks, held together by gravity. If one of these "rubble piles" spins fast enough, it's speculated that pieces could separate from it through centrifugal force and form a second collection ― in effect, a second asteroid.

Now researchers at Tel Aviv University, in collaboration with an international group of scientists, have proved the existence of these theoretical "separated asteroid" pairs.

Ph.D. student David Polishook of Tel Aviv University's Department of Geophysics and Planetary Sciences and his supervisor Dr. Noah Brosch of the university's School of Physics and Astronomy say the research has not only verified a theory, but could have greater implications if an asteroid passes close to earth. Instead of a solid mountain colliding with earth's surface, says Dr. Brosch, the planet would be pelted with the innumerable pebbles and rocks that comprise it, like a shotgun blast instead of a single cannonball. This knowledge could guide the defensive tactics to be taken if an asteroid were on track to collide with the Earth.

Researchers have modeled the likely path taken by Halley's comet in the 5th century BC and compared their findings to ancient Greek texts from the period. They now suggest the ancient Greeks saw the comet, which would make the sightings over two centuries earlier than previous known observations.

Chinese astronomers first described the comet in 240 BC, but in ancient Greece in 466-467 BC Greek authors described a meteor the size of a wagon that crashed into the Hellespont region of northern Greece during daylight hours, frightening the population and creating a tourist attraction that lasted five centuries. The ancient authors describe a comet in the sky at the time.

Researchers Daniel Graham, a philosopher, and Eric Hintz, an astronomer, from Brigham Young University at Provo in Utah, compared their model of the comet's likely path with the texts describing the meteor crash. Halley's comet would have been visible for 82 days maximum, depending on atmospheric conditions at the time, while the ancient texts say the comet was visible for 75 days.

Scientists studying sunspots for the past 2 decades have concluded that the magnetic field that triggers their formation has been steadily declining. If the current trend continues, by 2016 the sun's face may become spotless and remain that way for decades - a phenomenon that in the 17th century coincided with a prolonged period of cooling on Earth.

Sunspots appear when upwellings of the sun's magnetic field trap ionized plasma - or electrically charged, superheated gas - on the surface. Normally, the gas would release its heat and sink back below the surface, but the magnetic field inhibits this process. From Earth, the relatively cool surface gas looks like a dark blemish on the sun.

Astronomers have been observing and counting sunspots since Galileo began the practice in the early 17th century. From those studies, scientists have long known that the sun goes through an 11-year cycle, in which the number of sunspots spikes during a period called the solar maximum and drops - sometimes to zero - during a time of inactivity called the solar minimum.

The signals of GPS satellites could be used to monitor tsunamis as they sweep across the ocean. In the most detailed study to date of the effect, scientists have shown that even though open ocean tsunami waves are only a few centimetres high, they are powerful enough to create atmospheric vibrations extending all the way to the ionosphere, 300 kilometres up in the atmosphere.

The finding, the researchers hope, could hugely improve tsunami early-warning systems.

In a study published online on 1 September in Geophysical Research Letters¹, a team of French geophysicists was able to use these ionospheric effects to trace the progress of three recent tsunamis, including the one triggered by the 27 February earthquake in Chile, which had a magnitude of 8.8. The researchers showed that the strength of the ionospheric effects increased with the height of the wave.

The maximum height of that tsunami, which swept across the Pacific, was only 10 centimetres in mid-ocean, but low-lying tsunami waves can be more than 100 kilometres long. During a tsunami, hundreds of square kilometres of ocean rise and fall, nearly in unison. This produces a rhythmic movement in the atmosphere, generating a vertically propagating wave known as an internal gravity wave. The thinning air causes the wave to spread out vertically and the air movements become larger.

"At around 300 - 350 kilometres of altitude, the atmospheric wave has been amplified by a factor of 10,000 or more," says Lucie Rolland, a graduate student at the Paris Institute of Geophysics, whose PhD work spearheaded the study. "This means that a 10-centimetre tsunami wave at ocean level will induce atmospheric displacement reaching 1 kilometre."

Engineers at UC Berkeley have developed a pressure-sensitive electronic material from semiconductor nanowires that could one day give new meaning to the term "thin-skinned."

"The idea is to have a material that functions like the human skin, which means incorporating the ability to feel and touch objects," said Ali Javey, associate professor of electrical engineering and computer sciences and head of the UC Berkeley research team developing the artificial skin.

The artificial skin, dubbed "e-skin" by the UC Berkeley researchers, is described in a Sept. 12 paper in the advanced online publication of the journal Nature Materials. It is the first such material made out of inorganic single crystalline semiconductors.

A touch-sensitive artificial skin would help overcome a key challenge in robotics: adapting the amount of force needed to hold and manipulate a wide range of objects.

"Humans generally know how to hold a fragile egg without breaking it," said Javey, who is also a member of the Berkeley Sensor and Actuator Center and a faculty scientist at the Lawrence Berkeley National Laboratory Materials Sciences Division. "If we ever wanted a robot that could unload the dishes, for instance, we'd want to make sure it doesn't break the wine glasses in the process. But we'd also want the robot to be able to grip a stock pot without dropping it."

An instrument designed and built at the University of Arizona measured the isotopic composition of the Mars atmosphere, providing information about water on the planet.

Liquid water has interacted with the Martian surface throughout Mars' history, measurements by NASA's Phoenix Mars Lander suggest.

The findings, published in the Sept. 10 issue of the journal Science, also suggest that liquid water has primarily existed at temperatures near freezing, implying hydrothermal systems similar to Yellowstone's hot springs on Earth have been rare on Mars throughout its history.