Sea Ice Decline Spurs the Greening of the Arctic

Sea ice decline and warming trends are changing the vegetation in nearby arctic coastal areas, according to two University of Alaska Fairbanks scientists.

Uma Bhatt, an associate professor with UAF's Geophysical Institute, and Skip Walker, a professor at UAF's Institute of Arctic Biology, contributed to a recent review of research on the response of plants, marine life and animals to declining sea ice in the Arctic.

"Our thought was to see if sea ice decline contributed to greening of the tundra along the coastal areas," Bhatt said. "It's a relatively new idea."

The review appeared in a recent issue of Science magazine. It is a close, comprehensive look at how the losses of northern sea ice affect surrounding areas. Bhatt and Walker were two of ten authors.

The review team analyzed 10 years worth of data and research on the subject. The findings show that sea ice loss is changing marine and terrestrial food chains. Sea-ice disappearance means a loss of sea-ice algae, the underpinning of the marine food web. Larger plankton is thriving, replacing smaller, but more nutrient dense plankton. What that means exactly is not yet understood.

Above water, loss of sea ice has destroyed old pathways of animal migration across sea ice while opening new pathways for marine animals in others. Some animals and plants will become more isolated. In the case of the farthest north and coldest parts of the Arctic, entire biomes may be lost without the cooling effects of disappearing summer sea ice.

Walker, a plant biologist, says warming soils provide an opportunity for new vegetation to grow where less vegetation occurred previously. This contributes to a general greening of the Arctic that is visible from space. Bhatt, an atmospheric scientist, examined a 1982-2010 time series of remote sensing data to examine trends in sea ice, land-surface temperatures and changes in the vegetation abundance.

A surprise and puzzling finding shows that despite a general warming and greening of Arctic lands in North America, some areas in northern Russia and along the Bering Sea coast of Alaska are showing recent cooling trends and declines in vegetation productivity.

"We don't know why," Bhatt said.

Read more at Science Daily

Underwater Intelligence: How Do You Track a Fish Underwater?

How do you track a fish? There's no "Google Maps" for finding fish. The radio signals that are the backbone of traditional GPS cannot pass through seawater. But sound travels remarkably well, so scientists often use acoustic telemetry to estimate an individual fish's location. That means attaching an acoustic transmitter to a fish and then using a network of stationary underwater listening stations to monitor for the short clicking sounds that these tags emit. When a fish swims near to a receiver, its click is heard, and its individual code number is recorded.

Knowing your uncertainty

Even with this clicker-listener observation network in place, though, there's much uncertainty about a fish's whereabouts at any given time. To date, most researchers have used ad hoc methods to analyze their data, and typically have not quantified uncertainty.

"In science, knowing how certain or uncertain you are is often the prime objective," said Kevin C. Weng, manager of the Pelagic Fisheries Research Program at the University of Hawai'i at Mānoa and a graduate faculty member in the Department of Oceanography. "We're used to knowing within 20 feet where you can find that bison, wolf or bird. But underneath the ocean surface, we don't have the luxury of using GPS. So marine scientists use sound, which results in much lower accuracy."

But what is that accuracy? Martin W. Pedersen, a UH Mānoa postdoctoral fellow from Denmark, explains: "In the traditional tracking system, a fish is generally assigned the position of the receiver that detected it, even though the fish might be anywhere in that receiver's detection range. And if none of the receivers have heard from the fish for a while, no positions are assigned, even though the network may be providing some, albeit uncertain, information about the fish's whereabouts. For example, we could possibly estimate how far a fish could travel in a certain time since it was last heard, and could also infer locations where it isn't, due to the lack of detections."

A new statistical framework

Rethinking the traditional, ad hoc approach, Pedersen and Weng have proposed a new state-space model for analyzing fish movement data collected by marine observation networks. Their new model was recently published in the scientific journal Methods in Ecology and Evolution. Its goal is to quantify the uncertainty associated with this imperfect locating system, and to improve its accuracy.

"Previous methods were not formulated with the fish, ocean and acoustics in mind," said Pedersen. "They therefore do not exploit all available information, such as the biology of the fish limiting its range of possible movement."

Pedersen and Weng's new state-space model for estimating individual fish movement is two-part -- one part that models the fish behavior, and one that models the detection of that behavior.

"It tells us how the fish is moving," said Pedersen. "Does the fish swim in straight lines? Does it have a particular home range, or center of attraction, for its movements?"

The second part of the model estimates the likelihood of detecting a fish -- incorporating the detection probability, environmental noise, and both presence and absence data. When receivers are located close to each other, it can even help researchers triangulate positions. Acoustic telemetry works in much the same way that cell tower networks pin down the location of your mobile phone: The distance from your phone (or the fish tag) to several cell towers (or acoustic receivers) is measured, and circles of that radius are drawn around each tower (receiver). Where the circles intersect -- that's you (or the fish).

The observation model also uses negative data, or the lack of detections, in combination with the behavior model to estimate how far the fish may have traveled while undetected. "Knowing where the fish is not located actually tells you a lot about where it is located, and with our new method, we are able to utilize that information and achieve a better accuracy," Pedersen said.

Does it work in the real (underwater) world?

To field-test their model, the researchers turned to the spectacular tropical reef setting of Palmyra atoll in the central Pacific Ocean -- home to myriad fish, sharks, manta rays, whales and turtles.

With monitoring data collected for coral reef fish from 51 underwater observer stations at Palmyra Atoll, Pedersen and Weng used their state-space model to develop contour maps that provided a visual representation of the confidence regions for the locations of the fish over time, along with a home range estimate.

During daylight hours, fish locations were estimated with a 95% confidence region radius of 50 meters, at their most accurate.

Read more at Science Daily

A Fluffy Disk Around a Baby Star

An international team of astronomers that are members of the Strategic Exploration of Exoplanets and Disks with Subaru Telescope (SEEDS) Project has used Subaru Telescope's High Contrast Instrument for the Subaru Next Generation Adaptive Optics (HiCIAO) to observe a disk around the young star RY Tau (Tauri). The team's analysis of the disk shows that a "fluffy" layer above it is responsible for the scattered light observed in the infrared image. Detailed comparisons with computer simulations of scattered light from the disk reveal that this layer appears to be a remnant of material from an earlier phase of stellar and disk development, when dust and gas were falling onto the disk.

Since 2009, the five-year SEEDS Project (Note) has focused on direct imaging of exoplanets, i.e., planets orbiting stars outside of our Solar System, and disks around a targeted total of 500 stars. Planet formation, an exciting and active area for astronomical research, has long fascinated many scientists. Disks of dust and gas that rotate around young stars are of particular interest, because astronomers think that these are the sites where planets form--in these so-called "protoplanetary disks." Since young stars and disks are born in molecular clouds, giant clouds of dust and gas, the role of dust becomes an important feature of understanding planet formation; it relates not only to the formation of rocky, Earth-like planets and the cores of giant Jupiter-like planets but also to that of moons, planetary rings, comets, and asteroids.

As a part of the SEEDS Project, the current team of researchers used HiCIAO mounted on the Subaru Telescope to observe a possible planet-forming disk around the young star RY Tau. This star is about 460 light years away from Earth in the constellation Taurus and is around half a million years old. The disk has a radius of about 70 AU (10 billion kilometers), which is a few times larger than the orbit of Neptune in our own Solar System.

Astronomers have developed powerful instruments to obtain images of protoplanetary disks, and Subaru Telescope's HiCIAO is one of them. HiCIAO uses a mask to block out the light of the central star, which may be a million times brighter than its disk. They can then observe light from the star that has been reflected from the surface of the disk. The scattered light will reveal the structure of the surface of the disk, which is very small in scale and difficult to observe, even with large telescopes. Observers use HiCIAO with a 188 element adaptive optics system to reduce the blurring effects of Earthʼs atmosphere, making the images significantly sharper.

This team succeeded in capturing a near-infrared image (1.65 μm) associated with the RY Tau disk. Unlike many other protoplanetary disks, the disk emission is offset from the centre of the star. In contrast to longer wavelength observations, which are associated with the midplane of the disk, near-infrared, scattered light coming from the surface of the disk produced this offset, which provides information about the vertical structure of the disk.

Changes in structure perpendicular to the surface of a disk are much harder to investigate because there are few good examples to study. Therefore, the information about vertical structure that this image provides is a contribution to understanding the formation of planets, which depends strongly on the structure of the disk, including structures such as spirals and rings, as well as height.

The team performed extensive computer simulations of the scattered light, for disks with different masses, shapes, and types of dust. They found that the scattered light is probably not associated with the main surface of the disk, which is the usual explanation for the scattered light image. Instead, the observed infrared emission can be explained if the emission is associated with a fluffy upper layer, which is almost transparent and not completely transparent. The team estimated the dust mass in this layer to be about half the mass of Earthʼs Moon.

Read more at Science Daily

Richard III’s Skeleton Came Within Inches of Destruction

Leicester archaeologists have revealed the bones of Richard III came within inches of destruction.

A team from the University of Leicester Archaeological Services (ULAS) have discovered during a second, follow-up dig, a massive disturbance at the Grey Friars site where the bones of the medieval monarch were found last year.

The news comes one year on from when archaeologists began the Search for Richard III at the Grey Friars site on 25 August last year.

During their second excavation at the Grey Friars site last month, the archaeologists found a large area of the church which had been completely destroyed.

The area -- measuring over 5 metres by 10 metres -- was just inches away from Richard III's skull, meaning the remains of the Last Plantagenet King came very close to being destroyed.

The disturbance covers a far larger area than the remnants of the Victorian toilet which were also discovered near Richard's grave during the first dig last year.

Site director Mathew Morris said: "It's a miracle that Richard III's skeleton was where it was. To the east, there is a massive disturbance that has removed all evidence of the church -- which must have come within inches of his head.

"The disturbance is so big we didn't have all of it in the excavation area. We uncovered an area more than 5 metres by 10 metres. We never got to the bottom -- it is at least 1.8 metres deep.

"We don't know what caused it yet. It's possible it was related to the demolition of the Grey Friars church -- or it could have happened any time after the friary was disbanded. Whatever it was, it came very close to removing Richard's head.

"It's entirely possible that because he was underneath the Victorian outhouses, he was protected from it.

"We found some pottery remnants in the area, but until we have examined those we won't have any idea when the disturbance happened."

The team first started digging on the Grey Friars site on 25 August, 2012.

They came across Richard's remains on the very first day -- but didn't exhume the skeleton until they were able to determine where the bones were buried within the friary.

The archaeologists worked with a team of experts from a wide range of disciplines -- including genetics, osteoarchaeology, forensic pathology and genealogy -- to determine the skeleton's identity.

The results revealed that -- beyond reasonable doubt -- the remains were those of the medieval monarch, and the University announced its discovery to a global audience in February.

Read more at Science Daily

Why Can't Humans Regenerate Body Parts?

The idea that some humble life forms on our planet -- jellyfish, corals and the like -- are actually immortal seems to be as compelling as that vintage 1969 "Star Trek" episode about the 5,000-year-old man, born in ancient Mesopotamia, who was still around to meet Captain Kirk and his crew because he was unable to die.

Now, it has surfaced once again in research at the National University of Ireland-Galway's Regenerative Medicine Institute on Hydractinia echinata, a.k.a. the snail fur.

The snail fur is a pinkish mass of spines, tentacles and polyps just 20 to 30 millimeters in length, which makes it small enough to attach itself to the shells of hermit crabs along the Irish and British coast. The snail fur would seem unremarkable, except for one quality: according to Uri Frank, a scientist at the institute, the creature "in theory -- lives forever."

Immortality, though, is a concept that's largely in the eye of the beholder, as we learned from the brouhaha that erupted after a New York Times Magazine article trumpeted a Japanese scientist's assertion that Turritopsis dohrnii, a species of jellyfish, also lived forever. It turns out, though, that what Frank actually is talking about is the snail fur's ability to fully regenerate lost body parts.

"It sounds gruesome, but if it has its head bitten off, it simply grows another one within a few days," the Irish scientist explained in a recent Irish Times article about the research.

That's a little less like the immortal guy on "Star Trek" and a little more like claiming that your 1985 Pontiac Fiero will last forever, as long as you gradually replace all of its parts. But even so, being able to grow your own replacement parts whenever you needed one would a pretty nifty trick.

The snail fur is far from the only creature on the planet to have this ability. Earthworms, starfish, lobsters, snails, salamanders and scores of other creatures can produce their own replacement organs and/or limbs as well. A few mammals can regenerate themselves to a lesser degree as well; two species of African spiny mice, for example, have the ability to regrow lost sweat glands, fur and cartilage.

So if a zebra fish can grow a new tail, why can't we regenerate an arm or leg -- or a kidney or heart -- whenever we need a new one?

For the answer, we have to look at how we grow our bodies in the first place. In the womb, humans are built, piece by piece, by embryonic stem cells, which are highly pluripotent -- that is, able to divide and differentiate into various other sorts of cells, from nerve cells to muscle cells to blood cells.

Creatures that regenerate limbs and organs have stem cells that keep this ability throughout their life cycles. If a salamander’s leg is cut off, for example, its stem cells rush into action and form a fast-growing mass of undifferentiated cells called a regeneration blastema, which eventually will differentiate and form the various structures of a new limb.

But like most mammals, by the time we’re born, those pluripotent cells are replaced by somatic--AKA adult--stem cells, which can maintain and to a limited degree repair the part of the body in which they’re found. Adult stem cells in bone marrow, for example, can make new blood cells, and adult stem cells in the skin can help to replenish its layers. They also can grow scar tissue to seal off a wound. Humans do have some limited regenerative ability as well. We can’t grow back a lost limb, but as a 2013 article in Nature documented, children sometimes are able to grow back fingertips that have been accidentally amputated. And an adult human can regenerate a portion of his or her liver, if that organ is damaged.

Why we and other mammals lose most of our ability to grow new limbs or organs remains unclear. Some researchers believe that it's a natural consequence of our greater complexity as organisms.

It may be, for example, that the genetic mechanisms in our bodies that try to keep cancers from developing also would prevent a blastema from forming. Enrique Amaya, a developmental biologist at the University of Manchester in Great Britain, recently offered a different possible explanation.

Read more at Discovery News

Optical Illusions: Your Brain Is Way Ahead of You

Optical illusions may seem like nothing more than visual trickery. But they are actually a result of our brains trying to predict the future.

When light hits our retina, it takes about one-tenth of a second for our brain to translate that signal into perception. Evolutionary neurobiologist Mark Changizi says this neural delay makes our brains generate images of what it thinks the world will look like in one-tenth of a second. It's not always right.

“Your brain is slow, so you need to basically create perceptions that correct for that delay,” said Changizi, director of human cognition at 2AI Labs.

Creating an image of the very near future probably kept early humans alive because it kept them from bumping into dangerous objects or being attacked by a fast-moving predator.

Click through the following images and see how our ability to predict the future one-tenth of second in advance also messes with your mind.

BLURRED LINES

When images of objects flow across the retina, it activates all these different neurons in our brains. This is the mechanism by which the brain figures out how to extrapolate the next moment.

“When you move through the world, your eyes take snapshots,” said Chingazi. “During that snapshot, as something moves across your visual field, you don’t just end up with a dot on your retina, you end up with a blurred line on your retina.”

Our perception doesn’t see them, but the blurred lines make our brains realize that something is in motion. From there we can determine the direction of an object moving in our world. Since the blurred lines are all emanating from a single point in your visual field, they can inform you on the direction you’re going.

“Once you know the direction you’re going, you can determine how all these things would change in the next moment,” said Chingazi.

Take the above photo of “warp speed.” You don’t even have to question in what direction those blurred lines are taking you. Little did you know, "Blurred Lines" is more than just the most over-hyped song of the summer.

HERING ILLUSION

Perhaps the best representation of blurred lines and how they apply to optical illusions is the Hering illusion. Its radial spokes are blurred lines, all emanating from a single point. Those lines tell us where we are heading: forwards, towards the center.

The reason the two vertical lines appear to bow in the middle is because the radial lines suck our field of vision towards the center, as if we were in motion. In fact, those vertical lines are parallel, despite what our brain tells us. Our perception is actually showing us what those parallel lines look like in the next tenth of a second, the moment our gaze “passes through” the vertical lines, towards the vanishing point of the radial lines.

To simplify things, Chingazi suggests we imagine walking through a very tall doorway of a cathedral. When we’re really far away, the doorway sides seem parallel to one another. The angular distance between the top, middle and bottom of the door are all roughly the same.

“Once you’re really close or going through the cathedral doorway, the parts at eye-level are going to be wider apart,” he said. “When you look up, they actually converge like railroad tracks in the sky.”

Essentially, this is the same phenomenon that happens in the Hering illusion.

GRAND UNIFIED THEORY

Shapes aren’t the only objects that change as we move forward. Other factors like angular size -- how much of our visual field is taken up by an object – speed, distance and the color contrast between an object and its background also contribute to optical illusions.

Changizi determined that many illusions can be defined within his future-seeing process, so he created a chart with 28 categories that help organize what he calls his “grand unified theory.”

“This seven-by-four table really has one hypothesis that explains them all,” he said. “It makes a prediction across these 28 categories about what kind of illusions you should expect and how the illusions will reveal themselves across these 28 kinds of stimuli.”

The above illusion was created by a former student of Chingizi’s, and it demonstrates elements of speed, size and contrast. Move your head towards the center and the bright-white center appears to quickly fill the circle. Move your head backward and the dark perimeter appears to close in on the white center.

EBBINGHAUS

The orange circle on the left appears much smaller than the one on the right, when in fact they are the same size. This is the classic Ebbinghaus illusion, named after Hermann Ebbinghaus, the German psychologist who discovered it. British psychologist Edward Titchener popularized the illusion in the early 20th Century, as the illusion is also known as “Titchener circles.”

The juxtaposition of the circles’ sizes and distance from each other make them appear incongruent.

Read more at Discovery News

Wolves Howl Out of Loneliness

The “woe is me” sound of a wolf howl is tied to loneliness and affection for others, a new Current Biology study suggests.

What’s more, each howl appears to be uniquely matched to the quality of a specific wolf relationship.

This goes against prior speculation that howls are just a knee jerk reaction, with wolves acting out of instinct instead of anything particularly meaningful.

“Our results suggest the social relationship can explain more of the variation we see in howling behavior than the emotional state of the wolf,” Friederike Range of the Messerli Research Institute at the University of Veterinary Medicine Vienna, who worked on the study, said in a press release.

“This suggests that wolves, to a certain extent, may be able to use their vocalizations in a flexible way.”

Range and colleagues’ study looked at two packs of wolves living at Austria’s Wolf Science Center. Human handlers there typically take individual wolves out for walks on a leash, one at a time. The handlers noticed that, without fail, the other wolves would howl when one of their pack left them.

The researchers measured the howling wolves’ stress hormone levels to see if sheer anxiety led to the howling. They found that the amount of howling did not correspond to higher levels of the stress hormone cortisol.

Range said, “Our data suggest that howling is not a simple stress response to being separated from close associates but instead may be used more flexibly to maintain contact and perhaps to aid in reuniting with allies.”

Collected data on the wolves’ dominance status in the pack and their preferred partners determined that wolves howled longer and with more gusto when the missing wolf was a close compatriot and if the individual was of high status within the pack.

Read more at Discovery News

New Glue-Spitting Velvet Worm Found in Vietnam

Small bugs of the rain forest have many things to worry about, assuming they are capable of anxiety. But surely some of their more feared predators are velvet worms, a group of ancient animals that spit an immobilizing, gluelike material onto prey before injecting them with saliva and chomping down.

It turns out the velvet worm family is more diverse than thought: A new species has been found in the jungles of Vietnam. Unlike related velvet worms, this species has uniquely shaped hairs covering its body. It reaches a length of 2.5 inches (6 centimeters), said Ivo de Sena Oliveira, a researcher at the University of Leipzig, Germany, who along with colleagues describes the species in Zoologischer Anzeiger (A Journal of Comparative Zoology).

The paper and related work by Oliveira suggest thousands of unknown species of these creatures are waiting to be found throughout the world's tropical rain forests, he said. Research by Oliveira in the Amazon rain forest alone suggests there may be one new species of velvet worm about every 15 miles (25 kilometers), he told LiveScience.

Little-known glue-spitter

The animals are extremely difficult to find and little known, because they spend most of life hidden in moist areas in the soil, in rotting logs or under rocks, due in part to the fact that their permeable skin allows them to quickly dry out, Oliveira said. In some areas, "if you're not there at the right moment of the year, during the rainy season, you won't find them," he added. The rainy season is the one time of year this Vietnamese species exits the soil, he said.

Unlike arthropods (a huge group of animals that includes ants and spiders), velvet worms lack hard exoskeletons. Instead their bodies are fluid-filled, covered in a thin skin and kept rigid by pressurized liquid. This hydrostatic pressure allows them to walk, albeit very slowly, on fluid-filled, stubby legs that lack joints.

Slimed

Their slowness works to their advantage. To hunt, they sneak up on other insects or invertebrates. And that's when the sliming begins — velvet worms like the newfound species hunt by spraying a "net of glue" onto their prey from two appendages on their backs, Oliveira said. This nasty material consists of a mix of proteins that impedes movement. "The more the prey moves, the more it gets entangled," he said.

Oftentimes the velvet worms will eat any excess "glue," which is energetically costly to make. Although the animals have been shown to take down prey larger then themselves, they often choose smaller creatures, likely to ensure they don't waste their precious bodily fluids, Oliveira said.

Fossils show that velvet worms haven't changed much since they diverged from their relatives (such as the ancestors of arthropods and waterbears) about 540 million years ago, Oliveira said. Studies of velvet worms could help shed light on the evolution of arthropods, he added.

There are two families of velvet worm, one spread around the tropics, and another found in Australia and New Zealand. Members of the former group generally tend to be loners. But the other family may be more social. One 2006 study found that members of the species Euperipatoides rowelli can hunt in groups of up to 15, and that the dominant female eats first.

While it's not a surprise to find a new species of velvet worm, this is "great work by [these researchers] to actually characterize and name a new species from this region," said Nick Jeffery, a doctoral student at the University of Guelph who wasn't involved in the study.

Read more at Discovery News

Mystery Settlers Reached 'Step to Americas' Before Vikings

One of the first stepping stones for Europeans as they explored across the Atlantic to ultimately land in the Americas was colonized much earlier than previously thought -- and not by the Vikings, who were once thought to be the pioneers of those isles, researchers say.

The Faroe Islands are located about halfway between Norway and Iceland. They were the first stepping stones beyond the Scottish archipelago of the Shetlands for the Viking diaspora that culminated in the European discovery of continental North America in the 11th century, about 400 or 500 years before Christopher Columbus made his famous voyage.

Until now, scientists thought the Vikings undertook the first major settlement of the Faroes in the ninth century. Still, there were hints there might have been earlier arrivals there -- for instance, in about 825, the Irish monk Dicuil in the court of Charlemagne wrote of Irish hermits settling islands beforehand that may have been the Faroes, researcher Mike Church, an environmental archaeologist at the Durham University in England, told LiveScience in an interview.

Mystery settlers

Now, scientists have discovered firm archaeological evidence "for the human colonization of the Faroes by people some 300 to 500 years before the large-scale Viking colonization of the ninth century, although we don't yet know who these people were or where they came from," Church said in a statement.

The research took place at an archaeological site of Á Sondum on the island of Sandoy. The investigation revealed an extensive windblown sand deposit containing patches of burnt peat ash from human activity.

This ash contained barley grains burnt in domestic hearths, which carbon dating showed was pre-Viking. Barley is not indigenous to the Faroes, so it must have been either grown or brought to the islands by humans.

"This is the first archaeological evidence that proves there were humans there at the Faroes prior to the big Viking colonization event," Church said.

Humans would have spread these ashes onto the sands during the fourth to sixth centuries and sixth to eighth centuries. This practice was often seen in the North Atlantic region among Europeans during this period to stabilize the dunes and keep the wind from eroding them away.

"The majority of archaeological evidence for this early colonization is likely to have been destroyed by the major Viking invasion, explaining the lack of proof found in the Faroes for the earlier settlement," Church said.

It remains unknown who these newly discovered settlers were. Possibilities may include religious hermits from Ireland, late-Iron Age colonists from Scotland or pre-Viking explorers from Scandinavia. (The 10 Most Intrepid Explorers)

"Maybe these were intrepid explorers arriving from each of those areas," Church said, adding that the findings raise more questions than they answer.

"Although we don't know who the people were that settled here and where they came from, it is clear that they did prepare peat for use by cutting, drying and burning it, which indicates they must have stayed here for some time," researcher Símun Arge, of the National Museum of the Faroe Islands, said in a statement.

Questions of human settlement

The research challenges the scale, timing and nature of human settlement of the wider North Atlantic region.

"This also raises questions about the timing of human activity on other island systems where, similarly, evidence may have been destroyed," Church said.

Arge agreed. "We now have to digest these dates of this early evidence in relation to other sources and consider whether there may be other similar sites, elsewhere on the islands, which may be able to provide us with further structural archaeological evidence," Arge said.

It may be a major challenge finding more evidence of these ancient settlers, Church noted.

Read more at Discovery News

Brilliant Red Sprite Lightning Caught on Film

Amazing new photos and video of the elusive red lightning called sprites are helping researchers understand how the mysterious electric bursts form.

Sprites last less than a second as they dance on the tops of thunderstorms. Many viewers say the clusters of charged particles look like jellyfish — big, red balls with tendrils that reach down into the clouds. But red sprites take many shapes, from crowns to carrots, and researchers still don't why. Because few sprites are seen from the ground, thanks to obscuring storms, scientists are hunting them from the air.

Graduate student Jason Ahrns captured stunning images of sprites during several flights over the Midwest this summer aboard the National Center for Atmospheric Research's Gulfstream V research plane. Ahrns is part of a sprite-hunting team from University of Alaska, Fairbanks, the U.S. Air Force Academy and Fort Lewis College in Durango, Colo.

During the research flights, the scientists snapped high-speed photos and video, which will help them to better understand the chemical and physical processes behind the phenomenon.

"It's still not clear what exactly is happening in a sprite, and why there are different kinds of sprites," Ahrns told LiveScience in an email interview.

Sprites could also impact weather and climate by changing conditions in Earth's atmosphere, but scientists don't yet know the scale of the effect, Ahrns said. "We can't answer that without studying them."

While many questions remain about red sprites, some details have emerged since their existence was confirmed in 1989. Sprites form above thunderstorms, when a positively charged lightning bolt leaves the air above a thundercloud that is negatively charged. (Most lightning results from negatively charged bolts). The red color results from the interaction between charged particles and nitrogen, scientists believe.

"There's about one positive lightning stroke for every 10 regular negative strokes," said Ahrns, using the technical term for lightning bolt. "Most big storms probably produce a few sprites, and some produce lots of them. They're probably more common than people think, they're just very difficult to see since they're above the clouds."

Red sprites can race high toward space, up to 60 miles (96 kilometers) above the Earth. Astronauts aboard the International Space Station caught a sprite on camera in 2012. A sprite's red tendrils also reach down into the stratosphere, about 15 to 20 miles (25 to 32 km) above Earth's surface. They look brightest between 40 to 45 miles (65 to 72 km) up.

Read more at Discovery News