Life-Bearing Lake Possible on Icy Jupiter Moon

New research shows the jumbled ice blocks crowning the surface of Jupiter's icy moon Europa are signs of a large liquid lake the volume of the North American Great Lakes just below the surface, a key finding in the search for places where life might exist beyond Earth.

Drawing from studies of underground volcanoes in Iceland and Antarctica, scientists ran computer models to see if the chaotic formations on Europa's surface could be explained by the same geologic processes seen on Earth.

"We looked at melt underneath the ice and the fracture and collapse of ice shelves," Britney Schmidt, a postdoctoral fellow at the University of Texas at Austin's Institute for Geophysics, told Discovery News.

"We come with these large pockets of water that form lakes. As they melt they actually break up the ice above it, like what you see on Earth," she said.

"This is certainly the best model so far," Paul Schenk, a staff scientist with the Lunar and Planetary Institute in Houston, wrote in an email to Discovery News. "If we go back with penetrating radar instruments we should be able to see into the ice shell, determine the stratigraphy of the layers in the shell and verify which models works best."

Europa, which is slightly smaller than Earth's moon, is believed to have a large ocean of salty water deep beneath its frozen crust. These recently discovered lakes appear to be embedded closer to the surface.

"Europa has more water than all of Earth's oceans," planetary scientist Simon Kattenhorn, with the University of Idaho, told Discovery News.

While the ocean itself is of interest to scientists searching for life beyond Earth, a mechanism to churn the surface ice and subsurface water makes Europa an even more compelling target.

Read more at Discovery News

Leonardo’s Formula Explains Why Trees Don’t Splinter

The graceful taper of a tree trunk into branches, boughs, and twigs is so familiar that few people notice what Leonardo da Vinci observed: A tree almost always grows so that the total thickness of the branches at a particular height is equal to the thickness of the trunk. Until now, no one has been able to explain why trees obey this rule. But a new study may have the answer.

Leonardo’s rule holds true for almost all species of trees, and graphic artists routinely use it to create realistic computer-generated trees. The rule says that when a tree’s trunk splits into two branches, the total cross section of those secondary branches will equal the cross section of the trunk. If those two branches in turn each split into two branches, the area of the cross sections of the four additional branches together will equal the area of the cross section of the trunk. And so on.

Expressed mathematically, Leonardo’s rule says that if a branch with diameter (D) splits into an arbitrary number (n) of secondary branches of diameters (d1, d2, et cetera), the sum of the secondary branches’ diameters squared equals the square of the original branch’s diameter. Or, in formula terms: D2 = ∑di2, where i = 1, 2, … n. For real trees, the exponent in the equation that describes Leonardo’s hypothesis is not always equal to 2 but rather varies between 1.8 and 2.3 depending on the geometry of the specific species of tree. But the general equation is still pretty close and holds for almost all trees.

Botanists have hypothesized that Leonardo’s observation has something to do with how a tree pumps water from its roots to leaves. The idea being that the tree needs the same total vein diameter from top to bottom to properly irrigate the leaves.

But this didn’t sound right to Christophe Eloy, a visiting physicist at the University of California, San Diego, who is also affiliated with University of Provence in France. Eloy, a specialist in fluid mechanics, agreed that the equation had something to do with a tree’s leaves, not in how they took up water, and the force of the wind caught by the leaves as it blew.

Eloy used some insightful mathematics to find the wind-force connection. He modeled a tree as cantilevered beams assembled to form a fractal network. A cantilevered beam is anchored at only one end; a fractal is a shape that can be split into parts, each of which is a smaller, though sometimes not exact, copy of the larger structure. For Eloy’s model, this meant that every time a larger branch split into smaller branches, it split into the same number of branches, at approximately the same angles and orientations. Most natural trees grow in a fairly fractal fashion.

Because the leaves on a tree branch all grow at the same end of the branch, Eloy modeled the force of wind blowing on a tree’s leaves as a force pressing on the unanchored end of a cantilevered beam. When he plugged that wind-force equation into his model and assumed that the probability of a branch breaking due to wind stress is constant, he came up with Leonardo’s rule. He then tested it with a numerical computer simulation that comes at the problem from a different direction, calculating forces on branches and then using those forces to figure out how thick the branches must be to resist breakage (see illustration). The numerical simulation accurately predicts the branch diameters and the 1.8-to-2.3 range of Leonardo’s exponent, Eloy reveals in a paper soon to be published in Physical Review Letters.

“Trees are very diverse organisms, and Christophe seems to have arrived at a simple and elegant physical principle that explains how branches taper in size as you go from the trunk, through the boughs, up to the twigs,” says Marcus Roper, a mathematician at UC Berkeley. “It’s surprising and wonderful that no one thought of [the wind explanation] sooner.”

Read more at Wired Science

First Arabic Crusader Inscription Found

Israeli archaeologists have discovered the first ever Arabic Crusader inscription, they announced on Monday.

The epigraphic evidence emerged from a 800-year-old inscribed marble slab which originally sat in Jaffa's city wall.

Bearing the name of the "Holy Roman Emperor" Frederick II, and the date "1229 of the Incarnation of our Lord Jesus the Messiah," the inscription was found broken on the top, right, left and bottom.

"The script is peculiar but once the slab was reassembled, it was deciphered with little effort," Moshe Sharon, of Hebrew University, told Discovery News.

According to Sharon and colleague Ami Shrager, the inscription was drafted by Frederick's officials, or possibly even the emperor himself, who was fluent in Arabic.

"Muslim scholars attended Frederick's court in Sicily, where his main royal palace was located. There, he also had a harem that included a Muslim concubine," Sharon said.

The grandson of both Frederick Barbarossa and Roger II of Sicily, Frederick II (1194- 1250) was the Christian king who led the Sixth Crusade of 1228-1229.

A series of military campaigns launched by the Christian countries of western Europe, the Crusades spanned two centuries, from 1095 to 1291.

Wearing a large Christian cross embroidered on their armor and shields, tens of thousands of men fought the Muslims to restore Christian control in and near Jerusalem.

"Frederick succeeded, without resorting to arms, in achieving major territorial gains for the Crusader Kingdom," Sharon said.

The emperor's most important feat was the handing over of Jerusalem to the Crusaders by the Egyptian sultan al-Malik al-Kamil, who had been impressed with Frederick's knowledge of Arabic language.

Prior to achieving this agreement in 1229, the emperor, who had been excommunicated by Pope Gregory IX for not starting the Crusade earlier, fortified the castle of Jaffa and left in its walls two inscriptions, one in Latin and the other in Arabic.

Only a small fragment remains of the Latin inscription. It was studied in the 19th century by the French Orientalist and archaeologist Clermont-Ganneau who ascribed it to Frederick II.

The Arabic inscription lists all the titles of Frederick and the Italian provinces he ruled. It also stresses that Frederick is the Holy Roman Emperor, "the protector of the Pope in Rome" and the "King of Jerusalem" -- a crown "he put on his own head in the Church of the Holy Sepulcher in Jerusalem, and which he had assumed after marrying the 12 years old Yolanda the Queen of Jerusalem in 1225," Sharon said.

Read more at Discovery News

Psychedelic-Colored Insects Flew Ancient Skies

At least one moth 50 million years ago sported a yellow-green hue highlighted by blue, black and green-cyan accents, a team of researchers concludes.

The fashion forward moth, described in the latest PLoS Biology, represents the oldest known moth for which the original colors have been determined.

The discovery, made in Germany, could help scientists learn the colors of a wide variety of long-extinct creatures, including birds, fishes, and other insects, and shed light on color's function and evolution.

"We can work out what they looked like and what they used the colors for," Yale researcher Maria McNamara said in a press release.

Fossils rarely preserve evidence of original color, so we've only known the Dinosaur Era and other prehistoric times in black and white, although artists have taken creative liberties in adding color to drawings.

McNamara and her team, however, have figured out a way to tease color information out of fossils. Coloration, in turn, suggests how the long-dead individuals may have behaved and communicated, since color can play a role in both of those things.

The scientists figured out the colors by using electron microscopy and other techniques to examine fossilized scales of daytime moths that lived around 50 million years ago. The moths lived at what is now the Messel oil shale pit near Frankfurt, where numerous other high-quality fossils have been unearthed.

Evidence from anatomical details preserved in the scales helped establish the structural color of the moths' forewings, which you can see in the recreation image. McNamara says that structural colors are the brightest colors in nature -- purer and more intense than chemical pigments. Tissue design generates structural colors by scattering light.

The researchers believe the ancient day moth's colors served defensive purposes by either warning off predators, or serving as camoflauge.

Read more at Discovery News

Sweet Spot for Life's Chemistry Discovered

When scientists realized early Earth didn't have the right ingredients for life on its own, they started looking in space for the complex organic molecules needed to get things going.

Of particular interest is methanol, which can trigger the more complex chemistry that leads to amino acids, the building blocks for proteins and life.

"Methanol is the most complex molecule you can form at the really low temperatures in interstellar space," astronomer Douglas Whittet, with Rensselaer Polytechnic Institute, told Discovery News. "When you put methanol into a newly forming star system, you have some heat from a proto-sun and that's when methanol really takes off. It's the springboard for more exciting chemistry that follows."

In other words, find the methanol and scientists believe you find the chemical pathways to life.

"Searching for methanol in various regions in space will tell researchers where to look for other complex organic molecules, which will eventually lead to the formation of life," astronomer Sachindev Shenoy, with NASA's Ames Research Center in California, told Discovery News.

But where to look?

A new analysis by Whittet and colleagues shows there is a "sweet spot" around a few young stars where methanol production is cranking. What seems to be key is how fast molecules can reach dust grains, which serve as a scaffolding of sorts for chemical reactions.

"The rate of molecule accumulation on the particles can result in an organic boom or a literal dead end," Whittet said.

Not all young stars are suited for organic chemistry. Whittet's team found a range of methanol concentrations in clouds from practically zero to about 30 percent.

If molecules build up too quickly on the surfaces of dust grains, there's not enough time for chemical reactions to occur before they are buried by other molecules. If the buildup is too slow, there are fewer chances for chemical reactions.

The research has implications for understanding where to look for life and suggests it may be more plentiful, from a chemistry point of view, than previously thought.

Read more at Discovery News

Archeologists Discover a Huge Ancient Greek Commercial Area On Island of Sicily

Led by Professor Dr. Martin Bentz, Bonn archeologists began unearthing one of Greek antiquity's largest craftsmen's quarters in the Greek colonial city of Selinunte (7th-3rd century B.C.) on the island of Sicily during two excavation campaigns in September 2010 and in the fall of 2011.

The project is conducted in collaboration with the Italian authorities and the German Archaeological Institute. Its goal is to study an area of daily life in ancient cities that has hitherto received little attention.

"To what extent the ancient Greeks already had something like "commercial areas" has been a point of discussion in expert circles to this day," said Bonn archeologist Dr. Gabriel Zuchtriegel, a research associate who coordinates the Selinunte project together with Dr. Jon Albers from the Institut für Klassische Archäologie der Universität Bonn at the Chair of Prof. Dr. Martin Bentz. " A concentration of certain 'industries' and craftsmen in special districts does not only presuppose proactive planning; it is also based on a certain idea of how a city should best be organized -- from a practical as well as from a social and political point of view, e.g., who will be allowed to live and work where?" The University of Bonn excavations are now contributing to finding a new answer to such questions.

Huge kilns, used communally

Concentration in a certain city district applied primarily to potteries in Selinunte, which were massed on the edge of the settlement in the very shadow of the city wall. "Consequently, their smoke, stench and noise did not inconvenience the other inhabitants as much," explained Dr. Zuchtriegel. "At the same time, this allowed several craftsmen to use kilns and storage facilities together." The excavations showed that the potters joined cooperatives that shared in the use of gigantic kilns with a diameter of up to 7 meters. The craftsmen's district in Selinunte probably stretched for more than 600 meters along the city walls and is thus among the largest ones known today. The excavations are in the hands of faculty and students from Bonn and Rome -- and they are exhausting. For excavations go on in August and September, when the heat reaches its peak -- but in exchange, there is very little rain.

"This work is a challenge for all involved," commented dig manager Bentz. "This is no camping trip." But for students, it is a great opportunity to learn archeological methods by doing. The Bonn researchers were surprised to find even older remnants of workshops under the 5th c. kilns. While these finds have not been completely excavated yet, indications are -- so the archeologists -- that pottery workshops existed in the same location during the city's early phase in the 6th century B.C. This means that craftsmen were probably intentionally housed on the edge as early as during the design of the city, which was -- like many colonies -- planned on the drawing board.

Read more at Science Daily

Ancient Bronze Artifact from East Asia Unearthed at Alaska Archaeology Site

A team of researchers led by the University of Colorado Boulder has discovered the first prehistoric bronze artifact made from a cast ever found in Alaska, a small, buckle-like object found in an ancient Eskimo dwelling and which likely originated in East Asia.

The artifact consists of two parts -- a rectangular bar, connected to an apparently broken circular ring, said CU-Boulder Research Associate John Hoffecker, who is leading the excavation project. The object, about 2 inches by 1 inch and less than 1 inch thick, was found in August by a team excavating a roughly 1,000-year-old house that had been dug into the side of a beach ridge by early Inupiat Eskimos at Cape Espenberg on the Seward Peninsula, which lies within the Bering Land Bridge National Preserve.

Both sections of the artifact are beveled on one side and concave on the other side, indicating it was manufactured in a mold, said Hoffecker, a fellow at CU-Boulder's Institute of Arctic and Alpine Research. A small piece of leather found wrapped around the rectangular bar by the research team yielded a radiocarbon date of roughly A.D. 600, which does not necessarily indicate the age of the object, he said.

"I was totally astonished," said Hoffecker. "The object appears to be older than the house we were excavating by at least a few hundred years."

Hoffecker and his CU-Boulder colleague Owen Mason said the bronze object resembles a belt buckle and may have been used as part of a harness or horse ornament prior to its arrival in Alaska. While they speculated the Inupiat Eskimos could have used the artifact as a clasp for human clothing or perhaps as part of a shaman's regalia, its function on both continents still remains a puzzle, they said.

Since bronze metallurgy from Alaska is unknown, the artifact likely was produced in East Asia and reflects long-distance trade from production centers in either Korea, China, Manchuria or southern Siberia, according to Mason. It conceivably could have been traded from the steppe region of southern Siberia, said Hoffecker, where people began casting bronze several thousand years ago.

Alternatively, some of the earliest Inupiat Eskimos in northwest Alaska -- the direct ancestors of modern Eskimos thought to have migrated into Alaska from adjacent Siberia some 1,500 years ago -- might have brought the object with them from the other side of the Bering Strait. "It was possibly valuable enough so that people hung onto it for generations, passing it down through families," said Mason, an INSTAAR affiliate and co-investigator on the Cape Espenberg excavations.

The Seward Peninsula is a prominent, arrowhead-shaped land mass that abuts the Bering Strait separating Alaska from Siberia. The peninsula was part of the Bering Land Bridge linking Asia and North America during the last ice age when sea level had dropped dramatically, and may have been used by early peoples as a corridor to migrate from Asia into the New World some 14,000 years ago.

The artifact was discovered in August by University of California, Davis, doctoral student Jeremy Foin under 3 feet of sediment near an entryway to a house at Cape Espenberg. Other project members included Chris Darwent of UC Davis, Claire Alix of the University of Paris, Nancy Bigelow of the University of Alaska Fairbanks, Max Friesen of the University of Toronto and Gina Hernandez of the National Park Service.

"The shape of the object immediately caught my eye," said Foin, who spotted the soil-covered artifact in an archaeological sifting screen. "After I saw that it clearly had been cast in a mold, my first thought was disbelief, quickly followed by the realization that I had found something of potentially great significance."

The CU-led excavations are part of a National Science Foundation-funded project designed to study human response to climate change at Cape Espenberg from A.D. 800 to A.D. 1400, a critical period of cultural change in the western Arctic, said Mason. Of particular interest are temperature and environmental changes that may be related to Earth's Medieval Warm Period that lasted from about A.D. 950 to 1250.

"That particular time period is thought by some to be an analog of what is happening to our environment now as Earth's temperatures are rising," said Mason. "One of our goals is to find out how these people adapted to a changing climate through their subsistence activities."

The Cape Espenberg beach ridges, wave-swept deposits made of sand and sediment running parallel to the shoreline that were deposited over centuries, often are capped by blowing sand to form high dunes. The Cape Espenberg dwellings were dug into the dunes and shored up with driftwood and occasional whale bones.

The team is examining the timing and formation of the beach ridges as well as the contents of peat and pond sediment cores to help them reconstruct the sea-level history and the changing environment faced by Cape Espenberg's settlers. Information on past climates also is contained in driftwood tree rings, and the team is working with INSTAAR affiliate Scott Elias, a University of London professor and expert on beetle fossils, who is helping the team reconstruct past temperatures at Cape Espenberg.

While the hunting of bowhead whales was a way of life for Inupiat Eskimos at Barrow and Point Hope in northwestern Alaska 1,000 years ago, it is still not clear if the Cape Espenberg people were whaling, said Mason. While whale baleen -- a strong, flexible material found in the mouths of whales that acts as a food filter -- and a variety of whale bones have been found during excavations there, the sea offshore is extremely shallow and some distance from modern whale migration routes. However, there is evidence of fishing and seal and caribou hunting by the group, he said.

The Inupiat Eskimos are believed to have occupied Cape Espenberg from about A.D. 1000 until the mid-1800s, said Hoffecker. They are part of the indigenous Eskimo culture that lives in Earth's circumpolar regions like Alaska, Siberia and Canada.

Read more at Science Daily

X-ray Laser to Recreate Conditions at Earth’s Core

The very center of the Earth has been described as the “last white spot” on our globe: a mysterious super-hot chamber that we know surprisingly little about. An X-ray beamline at the European Synchrotron Radiation Facility (ESRF) in France will, hopefully, unlock some of its secrets.

The inner core of our planet, hiding 2,500 kilometers beneath the surface, endures about three and a half million times atmospheric pressure and a temperature thought to be roughly as hot as the surface of the sun.

The X-ray beam, called ID24, attempts to reproduce some of those extreme conditions in the lab. Diamond anvil cells squeeze a material to intense pressures, and laser pulses heat it to unimaginable temperatures. The samples may be no bigger than a speck of dust and the heat may only be applied for microseconds, but it’s the closest approximation of the Earth’s center that we can get.

This will allow scientists in various fields to discover what happens when you heat iron to 10,000 degrees C, what happens when materials undergo a fast chemical reaction or at what temperature a mineral will melt in the interior of a planet. It will hopefully answer some burning questions that keep geologists up at night.

Cosmologists, too. That elusive “warm dense matter” may well live inside large planets like Jupiter, and we know even less about them. ID24 allows sample volumes 10,000 times smaller than those at the high power laser facilities to be studied, making such experiments possible.

Read more at Wired Science

First Stars May Not Have Been Monsters

Astronomers are seeking to explore a little-studied time in our universe's history known as "the Dark Ages." The universe was dark in that no galaxies shined brightly as we see today. Yet somehow, out of this dark, mostly-hydrogen gas, the very first stars did form somehow, lighting up the cosmos for the very first time.

What these first stars were like is still a debate amongst astronomers since there is a lack of direct observations.

Astronomers can simulate the formation of stars under the conditions that were present in the very early universe. However, the scenario is complex on large and small scales and involves many physical and chemical processes, all which need to be tracked carefully.

Often, some assumptions and approximations must be made in order for the simulation to fit into a realistic computational space and time.

Many previous models of the first stars were semi-analytic, meaning that some processes were approximated through the use of equations, rather than just letting the simulation progress in a purely numerical way. These have long predicted that, in the absence of heavier elements such as carbon, nitrogen, and oxygen, that the first stars would be truly massive, reaching hundreds of times the mass of the sun before finishing their growth.

Such behemoths would live out very short lives and explode catastrophically in a type of supernova that is not seen in the universe today; a "pair-instability" supernova.

This collapse and subsequent explosion is so violent that it does not leave a black hole remnant behind, as other large supernovae do. However, the pattern of elements created by such a supernova should be detectable in the gas left over, now trapped in old "metal-poor" stars wandering the galaxy. (Remember, in this case, astronomers refer to "metals" as any element that is not hydrogen and helium. Sorry, chemists.)

The problem with this hypothesis up until now is that the pattern of elements in old, metal-poor stars does not match this prediction. Instead, it looks as if the gas was created in "regular" core-collapse supernovae that we still see today that herald the death of a star that is tens of times the mass of our sun. This explosion leaves behind a neutron star or black hole as a remnant.

This new simulation of a star forming in the early universe explains why this might be the case. The group of astronomers, led by Takashi Hosokawa of the Jet Propulsion Laboratory (JPL) at NASA, used radiation hydrodynamical simulations to plot out the birth and life of this model star. This means they used principles of fluid flow mechanics and took into account the effects that the light of the star itself has on the process.

They found that the protostar formed a disk of material around it, as was expected, from which material flowed onto the star-to-be. As the star got denser and hotter, its radiation heated and ionized some of the gas around it, until the pressure was too great and gas began to flow out from the polar regions of the star. This outflow expanded until it cut off the gas falling on to the disk around the star, thus cutting off the star's food supply.

Finally, the disk itself was blasted away by the star's bright light, and 100,000 years after the star began to form, it had reached 35 times the mass of the sun and had begun nuclear fusion in its core.

35 solar masses is still pretty huge, though not the hundreds of solar masses that were expected. This type of star may have been more typical of the first stars, leading to core-collapse supernovae within a few million years. Though the existence of the super-behemoth stars has not been ruled out, the early chemical evolution of the universe was probably dominated more like this kind of star.

Read more at Discovery News

Fastest Stellar Spinner Will Die a Violent Death

The sun rotates at a respectable 2 kilometers per second, which may sound pretty fast. But according to a study to be published in The Astrophysical Journal Letters (arXiv:1111.0157v1), a star has been detected in 30 Doradus (a.k.a. the Tarantula Nebula in the Large Magellanic Cloud, 160,000 light-years away) spinning at the breakneck speed of 600 kilometers per second!

According to Ken Croswell at ScienceMag.org, if the star spun just 20 percent faster, centrifugal forces would rip the star to shreds. If an aircraft could travel this fast, it could fly from New York to Los Angeles in a little under 7 seconds!

We often hear of rapidly spinning compact objects, like pulsars -- spinning, X-ray-emitting neutron stars -- but rapidly spinning normal stars are very rare. In the case of VFTS 102, it's a real oddity and it's a record-breaker.

The young, blue, O-type star must have been sped up in some way. After all, stars spinning this fast aren't born naturally.

The international team of astronomers working on this study think they know why VFTS 102 is in such a mess. When looking around the star's neighborhood, they noted a pulsar speeding away from VFTS 102, as if running from the scene of a crime. They believe the pulsar may also be the victim of the event that caused VFTS 102's strange spin.

Once a binary pair -- two stars mutually orbiting each other -- one of the stars exploded as a supernova. As the supernova detonated, leaving the pulsar behind as a supernova remnant, the ejected gas was dumped onto VFTS 102. The rapid increase in mass caused the star to be "spun up."

As mass was lost in an instant from one of the stars as it exploded, the gravitational bond between the stars was lost, causing the pair to be flung away from each other, much like a hammer-thrower releasing a hammer. This is why both the pulsar and VFTS 102 are flying apart.

Read more at Discovery News