Apr 25, 2015

Giant cosmic tsunami wakes up comatose galaxies

Galaxies are often found in clusters, which contain many 'red and dead' members that stopped forming stars in the distant past. Now an international team of astronomers, led by Andra Stroe of Leiden Observatory and David Sobral of Leiden and the University of Lisbon, have discovered that these comatose galaxies can sometimes come back to life. If clusters of galaxies merge, a huge shock wave can drive the birth of a new generation of stars -- the sleeping galaxies get a new lease of life. The scientists publish their work on 24 April in the journal Monthly Notices of the Royal Astronomical Society.

Galaxy clusters are like cities, where thousands of galaxies can be packed together, at least in comparison to the sparsely-populated space around them. Over billions of years, they build up structure in the universe -- merging with adjacent clusters, like growing cities absorb nearby towns. When this happens, there is a huge release of energy as the clusters collide. The resulting shock wave travels through the cluster like a tsunami, but until now there was no evidence that the galaxies themselves were affected very much.

Stroe and Sobral observed the merging galaxy cluster CIZA J2242.8+5301, nicknamed the 'Sausage', located 2.3 billion light years away in the direction of the constellation of Lacerta in the northern hemisphere of the sky. They used the Isaac Newton and William Herschel Telescopes on La Palma, and the Subaru, CFHT and Keck Telescopes on Hawaii, and found that far from 'watching from the back' the cluster galaxies were transformed by the shock wave, triggering a new wave of star formation.

Stroe comments: "We assumed that the galaxies would be on the sidelines for this act, but it turns out they have a leading role. The comatose galaxies in the Sausage cluster are coming back to life, with stars forming at a tremendous rate. When we first saw this in the data, we simply couldn't believe what it was telling us."

The new work implies that the merger of galaxy clusters has a major impact on the formation of stars. "Much like a teaspoon stirring a mug of coffee, the shocks lead to turbulence in the galactic gas. These then trigger an avalanche-like collapse, which eventually leads to the formation of very dense, cold gas clouds, which are vital for the formation of new stars," says Stroe.

Sobral adds: "But star formation at this rate leads to a lot of massive, short-lived stars coming into being, which explode as supernovae a few million years later. The explosions drive huge amounts of gas out of the galaxies and with most of the rest consumed in star formation, the galaxies soon run out of fuel. If you wait long enough, the cluster mergers make the galaxies even more red and dead -- they slip back into a coma and have little prospect of a second resurrection."

Read more at Science Daily

Second possible specimen of 'pocket shark' ever found

A very small and rare species of shark is swimming its way through scientific literature. But don't worry, the chances of this inches-long vertebrate biting through your swimsuit is extremely slim, because if you ever spotted one you'd be the third person to ever do so.

This species common name is the "pocket shark," though those in the field of classifying animals refer to it by its scientific name Mollisquama sp., according to a new study published in the international journal of taxonomy Zootaxa. While it is small enough to, yes, fit in your pocket, it's dubbed "pocket" because of the distinctive orifice behind its pectoral fin--one of many physiological features scientists hope to better understand.

"The pocket shark we found was only 5 and a half inches long, and was a recently born male," said Mark Grace of NOAA Fisheries' Pascagoula, Miss., Laboratory, lead author of the new study, who noted the shark displayed an unhealed umbilical scar. "Discovering him has us thinking about where mom and dad may be, and how they got to the Gulf. The only other known specimen was found very far away, off Peru, 36 years ago."

Interestingly, the specimen Grace discovered wasn't found it the ocean, per se; rather in the holdings of NOAA's lab in Pascagoula. It was collected in the deep sea about 190 miles offshore Louisiana during a 2010 mission by the NOAA Ship Pisces to study sperm whale feeding. Grace, who was part of that mission after the rare shark was collected, and upon uncovering the sample at the lab years later, recruited Tulane University researchers Michael Doosey and Henry Bart, and NOAA Ocean Service genetics expert Gavin Naylor, to give the specimen an up-close examination.

A tissue sample was collected, and by tapping into the robust specimen collection of Tulane University's Biodiversity Research Institute, scientists were able to place the specimen into the genus Mollisquama. Further genetic analysis from Naylor indicate that pocket sharks are closely related to the kitefin and cookie cutter species, fellow members of the shark family Dalatiidae. Like other Dalatiidae shark species it is possible that pocket sharks when hungry may remove an oval plug of flesh from their prey (various marine mammals, large fishes and squid).

The specimen is part of the Royal D. Suttkus Fish Collection at Tulane University's Biodiversity Research Institute in Belle Chasse, La., and it is hoped that further study of the specimen will lead to many new discoveries. Already, the specimen--when compared to the 1979 specimen taxonomic description--is found to have a series of glands along the abdomen not previously noted. Partners at the Smithsonian Natural Museum of Natural History in Washington, D.C., and American Natural History Museum in New York City have also contributed to the study of this shark.

Read more at Science Daily

Apr 24, 2015

Oil and Gas Boom May Permanently Harm Ecosystems

Oil and gas drilling in North America is turning the Central Plains into an industrial landscape and causing long-lasting damage to ecosystems, reports a study in the April 24 issue of Science.

Three Yellowstone National Parks worth of land have been filled with well pads, road and storage facilities, from 2000 to 2012.

Satellite data was used to measure the amount of carbon stored by plants, which the authors write is an effective means to gauge the health of ecosystems: "It is a fundamental and supporting ecosystem service that is the basis for all life on Earth" affecting the ability to grow food, biodiversity and wildlife habitat.

"Nearly half of wells drilled in this time period occurred in already highly or extremely water-stressed regions," the study reports. "As refracturing becomes more common to yield greater production, oil and gas development adds to an already fraught competition among agriculture, aquatic ecosystems, and municipalities for water resources, in addition to concerns of water quality"

The impact of the transformation of the Great Plains is hard to detect when viewing a single region, that authors write, but the degradation has lasting impacts for the continent.

The effect is possibly permanent, because recovery of drilled land hasn't kept up with the pace of drilling.

From Discovery News

Rare Bronze Owl Brooch Found on Danish Island

Archaeologists excavating an Iron Age settlement on the Baltic island of Bornholm in Denmark have unearthed a unique enameled bronze clasp.

Cast as a flat piece of bronze and decorated with green enamel and glass disks in brilliant red, yellow, and black colors, the brooch is shaped like an owl and dates between 100-250 A.D.

“The bird’s big black glass pupils seem to stare directly back at you,” Ulla Lund Hansen, a leading scholar in the field of Roman Iron Age research, and Christina Seehusen, archaeologist at Bornholm Museum, wrote in the Danish archaeology magazine Skalk.

“Its large, luminous eyes are made even more dramatic by the stunning inlays of orange glass around the pupils,” she added.

The rare brooch, which measures just 1.5 by 1.5 inches, would have been used to fasten a man’s cloak. It was found in the Roman-age soil deposits of an ancient house in September 2014, but only now the find was made public.

“It is very uncommon to find such items in a settlement context in Denmark. We usually find these things only in burials,” Seehusen told Discovery News.

“The settlement was unusual in itself, as it was extremely well preserved compared to typical standards,” she said.

Indeed, on the settlement site Seehusen’s team found very well preserved remains of workshops, pottery, traces of houses and other buildings.

“We found Roman coins representing Faustina the Younger [the Empress consort to Marcus Aurelius (161-175 AD)] a bronze spur, several dress pins, bronze and iron brooches, glass beads, iron smelting cinders and plenty of animal bones from pig, cattle, horse, bird, fish and dog,” Seehusen said.

The brooch, or fibula, was probably made along the Roman frontier that ran along the Danube and the Rhine in what is now Germany.

How it ended up on Bornholm, an island in the middle of the Baltic Sea, remains a mystery.

“We can only guess who the original owner was and how it came to be preserved on the island,” Seehusen said.

The unusual piece represents a personal item, which is very rarely found outside the borders of the Roman Empire. It was possibly owned by a person who served as a mercenary in the Roman army in the northern provinces.

With its unusal shape and bright colors, it probably provided its owner with a great level of prestige.

“Perhaps it was lost or maybe it was deliberately hidden for reasons known only to its owner. Most likely, we will never know the brooch’s full story,” Seehusen said.

Read more at Discovery News

Woman's 'Embryonic Twin' Not Really an Embryo, Or a Twin

An Indiana woman's brain tumor turned out to contain hair, bone and teeth, and has been dubbed her "embryonic twin" — but experts say that such tumors are not actually twins, nor are they embryos.

The 26-year-old patient, Yamini Karanam, underwent brain surgery in Los Angeles after she started having problems understanding conversations and things she read, according to NBC Southern California. Doctors discovered she had a teratoma, a type of tumor that can contain all three of the major cell types that are found in an early stage human embryo.

Although these tumors can originate during embryonic development, they aren't embryos, and they are not a person's "twin." They arise from germ cells, which are the cells that go on to later develop into a person's gametes (such as sperm and eggs). At early states, germ cells have the ability to turn into any cell in the body.

The type of tumor that Karanam had occurs "when a person's own germ cell multiplies abnormally and differentiates into various different, normal tissues, in an abnormal place," said Dr. Cathy Burnweit, chief of pediatric surgery at Nicklaus Children's Hospital in Miami. "It has many of the components that a normal body would have, but it is in no way a twin," Burnweit said. Rather, identical twins occur when a fertilized egg divides in two, she said.

Because teratomas can have all three of the cell types found in the developing embryo, they can contain a variety of tissues, including cartilage, bone and hair, said Dr. Amir Dehdashti, director of cerebrovascular neurosurgery research at North Shore University Hospital in Manhasset, New York.

Teratomas can even contain lung or muscle tissue, or tissue of the gastrointestinal tract, said Dr. Adrienne Bonham, an associate professor of obstetrics and gynecology at the University of Rochester Medical Center.

Typically, during the development of a human embryo, germ cells migrate to the gonads. Teratomas are what can result if these germ cells end up in the wrong place, according to the Dana-Farber Cancer Institute. The most common places for teratomas are the ovaries, testes and the tailbone, according to the National Cancer Institute.

Read more at Discovery News

'Spider' Patterns on Pluto Await Spacecraft

Pluto is entering its ice geyser season – a time when sunlight hits the dwarf planet's icy north pole and triggers eruptions of nitrogen ice and gas that spray across the surface, possibly leaving dark spidery patterns.

That's what some astronomers and planetary scientists hope to see, anyhow, when the New Horizons spacecraft makes its flyby of the mysterious dwarf planet in July.

The evidence of lurking Plutonian spiders has come from some remarkable observations made over many years with ground telescopes and the Hubble Space Telescope, which can't resolve any details of Pluto's surface, but can confirm that unprecedented color and lighting changes have been underway in the last four years.

"We are pretty certain there is some kind of movement of frost," said Bonnie Buratti of NASA's Jet Propulsion Laboratory. The evidence is light curves collected by telescopes which show how the planet reflects light as it spins on its axis.

Those curves were compared to simulated light curves which assume there is no frost rising from polar ice caps and depositing in other places – darkening some places while lightening others. The modeled light curves do not match what astronomers have been seeing in recent years on the real Pluto.

"We compared it and for the last four years we've had substantial changes," Buratti told DNews.

The changes are happening at a time when Pluto is moving further from the sun, but it's also at a time when the north pole of the tilted planet is being turned towards the Sun. That creates a northern summer in the same way that summers happen on Earth. Buratti is the lead author on a paper about Pluto's discovery which has been accepted for publication by Astrophysical Journal Letters.

"We are pretty close to polar summer – so there is a lot of frost there to sublimate," she said, referring to the process where solid ice turns directly into gas, skipping the liquid phase.

The sun's rays – even at Pluto's current position 32 times further from the sun than Earth – should be enough to penetrate the nitrogen ice that's likely covering Pluto's polar cap. The ice could trap enough energy to covert some of the ice into pockets of gas. That gas would build up pressure until it blasts through the surface, spraying crystals of nitrogen ice all about in a sometimes spidery looking pattern.

This spider-making process would seem far-fetched, except that researchers have seen it before on other worlds.

"There are good analogues on the polar caps of Mars," said astronomer Will Grundy of Lowell Observatory in Arizona.

Vast amounts of carbon dioxide sublimate from martian polar caps when they are warmed by the sun, not only leaving telltale patterns on the surface, but also seasonally ramping up the atmospheric pressure of the entire Red Planet.

An even better analogue, however, is Triton, Neptune's giant moon. Triton is much colder and further from the sun than Mars, and it's thought to be a veritable twin of Pluto. Like Pluto, the primary gas at work on Triton is nitrogen (on Mars it's carbon dioxide). Two gas eruptions on Triton were witnessed by the Voyager 2 spacecraft way back in 1989.

Read more at Discovery News

Apr 23, 2015

Teeth Implicate Humans in Neanderthal Extinction

Ancient teeth from Italy suggest that the arrival of modern humans in Western Europe coincided with the demise of Neanderthals there, researchers said.

This finding suggests that modern humans may have caused Neanderthals to go extinct, either directly or indirectly, scientists added.

Neanderthals are the closest extinct relatives of modern humans. Recent findings suggest that Neanderthals, who once lived in Europe and Asia, were closely enough related to humans to interbreed with the ancestors of modern humans — about 1.5 to 2.1 percent of the DNA of anyone outside Africa is Neanderthal in origin. Recent findings suggest that Neanderthals disappeared from Europe between about 41,000 and 39,000 years ago.

Scientists have hotly debated whether Neanderthals were driven into extinction because of modern humans. To solve this mystery, researchers have tried pinpointing when modern humans entered Western Europe.

Modern human or Neanderthal?

The Protoaurignacians, who first appeared in southern Europe about 42,000 years ago, could shed light on the entrance of modern humans into the region. This culture was known for its miniature blades and for simple ornaments made of shells and bones.

Scientists had long viewed the Protoaurignacians as the precursors of the Aurignacians — modern humans named after the site of Aurignac in southern France who spread across Europe between about 35,000 and 45,000 years ago. Researchers had thought the Protoaurignacians reflected the westward spread of modern humans from the Near East — the part of Asia between the Mediterranean Sea and India that includes the Middle East.

However, the classification of the Protoaurignacians as modern human or Neanderthal has long been uncertain. Fossils recovered from Protoaurignacian sites were not conclusively identified as either.

Now scientists analyzing two 41,000-year-old teeth from two Protoaurignacian sites in Italy find that the fossils belonged to modern humans.

"We finally have proof for the argument that says that modern humans were there when the Neanderthals went extinct in Europe," study lead author Stefano Benazzi, a paleoanthropologist at the University of Bologna in Ravenna, Italy, told Live Science.

The researchers investigated a lower incisor tooth from Riparo Bombrini, an excavation site in Italy, and found it had relatively thick enamel. Prior research suggested modern human teeth had thicker enamel than those of Neanderthals, perhaps because modern humans were healthier or developed more slowly. They also compared DNA from an upper incisor tooth found in another site in Italy — Grotta di Fumane — with that of 52 present-day modern humans, 10 ancient modern humans, a chimpanzee, 10 Neanderthals, two members of a recently discovered human lineage known as the Denisovans, and one member of an unknown kind of human lineage from Spain, and found that the Protoaurignacian DNA was modern human.

"This research really could not have been done without the collaboration of researchers in many different scientific research fields — paleoanthropologists, molecular anthropologists, physical anthropologists, paleontologists and physicists working on dating the fossils," Benazzi said.

Killing off Neanderthals

Since the Protoaurignacians first appeared in Europe about 42,000 years ago and the Neanderthals disappeared from Europe between about 41,000 and 39,000 years ago, these new findings suggest that Protoaurignacians "caused, directly or indirectly, the demise of Neanderthals," Benazzi said.

It remains unclear just how modern humans might have driven Neanderthals into extinction, Benazzi cautioned. Modern humans might have competed with Neanderthals, or they might simply have assimilated Neanderthals into their populations.

Moreover, prior research suggests that Neanderthals in Europe might have been headed toward extinction before modern humans even arrived on the continent. Neanderthals apparently experienced a decline in genetic diversity about the time when modern humans began turning up in Europe.

"The only way we might have proof of how modern humans caused the decline of Neanderthals is if we ever find a modern human burying a knife into the head of a Neanderthal," Benazzi joked.

Read more at Discovery News

Virtual Telescope Readies to Image Black Hole's 'Ring of Fire'

With the addition of a telescope at the southern-most point of Earth, the Event Horizon Telescope (EHT) now spans the diameter of our planet and, when the vast project goes online, astronomers will get their first glimpse of the bright ring surrounding a supermassive black hole.

Using a method known as Very Long Baseline Interferometry, or VLBI, astronomers can combine the observing power of many telescopes situated at distant locations around the planet. The distance between those observatories, known as the “baseline,” then mimics a virtual telescope of that diameter. So, if you have telescopes dotted across one hemisphere of the globe, spanning 5,000 miles, you are, in effect, mimicking a giant telescope with a gargantuan diameter of 5,000 miles.

Of course, it isn’t a “simple” task of networking a bunch of telescopes and pointing them at a celestial object in the hope of gaining some usable data, but as interferometer communications hardware and computational software becomes more sophisticated, grand projects such as the EHT are starting to see the light of day. Or, in this case, the light generated by the invisible boundary surrounding a supermassive black hole.

Now, in an attempt to make direct observations of the supermassive black hole in the center of our galaxy, located at a powerful radio emission source called Sagittarius A*, the South Pole Telescope (SPT) at the National Science Foundation’s Amundsen-Scott South Pole Station has been linked to the EHT and the stage is set for a historic new era of exploring the most extreme objects in the known universe.

The SPT is a 10-meter telescope that is sensitive to millimeter wavelengths of radiation tasked with the day job of making high-resolution images of cosmic microwave background radiation, or CMB. By linking the observatory with the EHT, this telescope’s unique location will give the vast VLBI project a huge boost.

“Now that we’ve done VLBI with the SPT, the Event Horizon Telescope really does span the whole Earth, from the Submillimeter Telescope on Mount Graham in Arizona, to California, Hawaii, Chile, Mexico, Spain and the South Pole,” said Dan Marrone of the University of Arizona. “The baselines to SPT give us two to three times more resolution than our past arrays, which is absolutely crucial to the goals of the EHT. To verify the existence of an event horizon, the ‘edge’ of a black hole, and more generally to test Einstein’s theory of general relativity, we need a very detailed picture of a black hole. With the full EHT, we should be able to do this.”

It is predicted that when the EHT goes online, it will be 1,000 times more powerful than the Hubble Space Telescope and it will need all the power it can muster if we are to resolve the bright ring or crescent thought to surround the supermassive black hole in the Milky Way’s core. Although the supermassive black hole is 4 million times the mass of our sun, at a distance of 26,000 light-years, its predicted size will be tiny from our perspective.

“Because it is smaller than Mercury’s orbit around the sun, yet almost 26,000 light-years away, studying its event horizon in detail is equivalent to standing in California and reading the date on a penny in New York,” writes a University of Arizona press release.

But, should the EHT be able to achieve this monumental task, astrophysicists are getting excited for what we’ll see.

If our current understanding of how black holes work — and if some of the finer details of Einstein’s general theory of relativity holds up in the region immediately surrounding the black hole — we have a basic idea of what we’ll see. Although the event horizon is the point of no escape even for light and we shouldn’t see anything, just above the event horizon, extreme physics generate powerful radiation. In which case, the EHT should resolve a partial or full ring-like structure; energetic radiation glowing around a very definite dark shadow — this shadow being the event horizon.

And the best thing is, at that moment, when the event horizon ring is finally resolved, we’ll know whether or not black holes act as we expect. This will also be the first ever direct observations of the structure surrounding a black hole.

Read more at Discovery News

Hubble at 25: Space Telescope's Top Science Discoveries

Dark Energy

Hubble’s scientific bounty has benefited a wide range of astronomical and astrophysical fields, including the study of planets, moons and small icy bodies in the outer solar system and the cosmological history of the universe. Here’s a look at a few of Hubble’s greatest hits.

While scientists have published nearly 13,000 papers on Hubble-related studies, one topic earned researchers the 2011 Nobel Prize in Physics. In a pair of related investigations, astrophysicists Saul Perlmutter, with NASA’s Goddard Space Flight Center, Brian Schmidt, with the Australian National University, and Adam Riess, with Johns Hopkins University, discovered that the speed with which the universe is expanding is increasing.

The still-unexplained phenomenon, which would be akin to throwing a ball up in the air and having it pick up speed and keep going, is referred to as “dark energy.” Scientists used Hubble and ground-based telescopes to inventory a type of exploding star that puts out the same amount and type of radiation wherever it is found. The supernova can serve as a yardstick, since like a line of streetlamps, the closer ones will appear brighter than the lights of the same brightness that are farther away. Hubble has found these “standard candle” supernovas in nearby and very distant galaxies.


Another field that didn't even exist when Hubble was launched 25 years ago is the study of planets beyond the solar system. Astronomers discovered the first so-called exoplanet in 1992. In 2008, a year before NASA’s planet-hunting Kepler space telescope was launched to look for Earth-sized worlds around distant stars, Hubble took the first visible-light snapshot of a planet beyond the solar system.

Estimated to be no more than three times Jupiter's mass, the planet, called Fomalhaut b, orbits the bright southern star Fomalhaut, located 25 light-years away in the constellation Piscis Australis (the Southern Fish). Astronomers followed up images of the star’s planet-forming dust ring with a photograph of a point source of light lying 1.8 billion miles inside the ring's inner edge.

Search for Life

The search for planets beyond the solar system is strongly motivated by the age-old question about whether life exists beyond Earth, a quest that also underpins the robotic exploration of Mars and the monitoring of radio waves for signs of extraterrestrial intelligence, among other projects.

Much of the cutting edge research uses a planet-hunting technique successfully demonstrated by NASA’s Kepler space telescope, which found thousands of planets as they passed in front of their parent stars, relative to the telescope’s line of sight. Hubble scientists used the so-called “transit” technique to chemically analyze starlight shining through a planet’s atmosphere. So far, Hubble has found carbon dioxide, organic molecules and even water vapor in the atmospheres of exoplanets.

Black Holes

Black holes, as the term implies, can’t be directly detected, so jammed full of matter that their gravitational fists traps even photons of light. But they leave telltale footprints on the stars, gas and dust that they encounter and consume. Hubble’s ability to make out the motions of stars and dust and the centers of galaxies provided evidence that a supermassive black hole lies at the heart of almost all galaxies (including our own Milky Way.) Astronomers believe galaxies and black holes grew up together, though exactly how that process unfolds is still a mystery.

Read more at Discovery News

Stunning Hubble Silver Anniversary Picture Unveiled

NASA kicked off a series of Hubble anniversary tributes Thursday by unveiling a new image taken by the telescope, which was launched into orbit on April 24, 1990.

Managers chose a display of celestial fireworks in a giant cluster of stars known as Westerlund 2, located about 20,000 light-years away in the constellation Carina.  The cluster, comprised of about 3,000 stars, is very young by astronomical standards, just about 2 million years old.

“This spectacular image shows a cloud of dense gas and dust, the gas is collapsing forming new stars,” said NASA’s chief scientist John Grunsfeld, an astronomer and former astronaut who was part of three different Hubble repair and servicing crews.

“It’s a very vigorous breeding ground for new stars … and it contains some of the galaxy’s hottest, brightest and most massive stars that we know of,” added Hubble project scientist Jennifer Wiseman, with NASA’s Goddard Space Flight Center in Greenbelt, Md.

“What’s great about Hubble’s sharp resolution, is that we can differentiate star from star even in crowded regions like this cluster. This helps us scientifically to be able to understand what kinds of stars are in this cluster, how they’re different from one another, how the population may have formed in the first place. We can study the characteristics because of Hubble’s exquisite sensitivity and resolution,” Wiseman said.

The image blends visible-light and near-infrared wavelengths. In the surrounding dust clouds, red represents hydrogen and the bluish-green hues are mostly oxygen.

“This is really an exciting a week for astronomers and people who love astronomy all over the world,” Wiseman said.

Read more at Discovery News

Apr 22, 2015

What Male and Female Stegosaurus Looked Like

Paleontologists are just now confirming what has long been suspected: male and female dinosaurs sometimes — and perhaps always — looked different from each other.

At least that appears to be true for Stegosaurus, a large plant-eating dinosaur living 150 million years ago, that sported rows of bony plates on top of its long back, and formidable-looking spikes at the end of its tail.

Authors of the new research, published in the journal PLOS One, argue it’s first convincing evidence for sexual differences in a species of dinosaur.

Initially, scientists Michael Benton and Evan Saitta thought that certain Stegosaurus-like skeletons represented different species. Then they started to realize that they were actually looking at male and female members of the same species.

“Evan made this discovery while he was completing his undergraduate thesis at Princeton University,” Benton, who is director of the Masters in Paleobiology Program at the University of Bristol, said in a press release.

Anatomical differences between males and females of the same species are collectively known as “sexual dimorphism.” Not all species exhibit this, but it’s obviously very common among living animals. Think of the manes of male lions, for example, or the antlers of male deer.

In the case of Stegosaurus, it appears that the primary difference had to do with the look and arrangement of their bony plates. Some Stegosaurus had wide plates while some had tall, with the wide plates being up to 45 percent larger than the tall plates.

Benton and Saitta studied Stegosaurus fossils unearthed in Montana. Puzzled by the plate variations, they CT-scanned samples from the plates, to see if the observed differences might reflect distinct growth stages. This was ruled out, however, because the bone tissues had ceased growing in both types.

The researchers also noted that the skeletal differences were not associated with a separation of ecological niches, which would have been expected if the two types were different species.

With these and other possibilities ruled out, Saitta concluded that the best explanation for the two varieties of plates is that one type belonged to males and the other to females.

“As males typically invest more in their ornamentation, the larger, wide plates likely came from males,” he explained. “These broad plates would have provided a great display surface to attract mates. The tall plates might have functioned as prickly predator deterrents in females.”

Read more at Discovery News

Dinosaur Egg Stash Found During China Roadwork

Road work in the southern China city of Heyuan was interrupted on Sunday when construction workers noticed something unusual in the ground — a fat stash of dinosaur eggs — 43, to be exact.

The discovery adds to an already impressive collection of dinosaur eggs discovered in the city, which calls itself "Home of Dinosaurs."

The Heyuan Dinosaur Fossil Museum was recognized with a Guinness World Record in 2004 for housing the largest collection of dinosaur egg fossils. That record was 10,008. Now that number will grow by 43.

Among the newly recovered eggs, 19 were fully intact and the largest was more than 7 inches in diameter.

Why so many dinosaur eggs in Heyuan? Was there something appealing there for brooding dinos back in the day? Apparently it has to do with the region’s soil.

Du Yanli, the museum's curator, told CCTV News, "The eggs were found in the rock strata of red sandstone, an environment in which other dinosaur egg fossils have also previously been found."

Most of the dinosaur eggs currently in the city's museum were deposited by oviraptorid and duck-billed dinosaurs, which roamed the Earth 89 million years ago. Cu Yanli said they will need to further examine the new eggs to determine what species of dinosaur laid them millions of years ago.

From Discovery News

Our 'Pale Blue Dot'

Check out the image above. Doesn't seem like much, does it? Maybe someone snapped a picture while the lens cap was still on.

Take another look. On closer examination, the picture resolves into four bands of light. Check out the band farthest to the right. Look about halfway down. There is a small dot, brighter than its surroundings. It isn't a speck of dust, it isn't a smudge on the camera lens or on your monitor.

It's us.

It's all of us.

It's Earth.

In 1990, at the request of famed astronomer and broadcaster Carl Sagan, NASA sent a command to the Voyager 1 spacecraft, on its way out of the Solar System, to turn its camera in the direction from which it came. The above image is the result.

The picture is frequently referred to as the "pale blue dot," and provided both the frontispiece and the title for one of Sagan's most celebrated books, published in 1994. Sagan himself, as was his wont, expressed its significance with an eloquence to which most of us can only aspire:

From this distant vantage point, the Earth might not seem of particular interest. But for us, it's different. Look again at that dot. [...] On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, every hunter and forager, every hero and coward, every creator and destroyer of civilization, every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every "superstar," every "supreme leader," every saint and sinner in the history of our species lived there – on a mote of dust suspended in a sunbeam.

Read more at Discovery News

First Exoplanet Discovered by Reflected Visible Light

Astronomers have detected an exoplanet's visible-light spectrum directly for the first time ever, a milestone that could help bring many other alien worlds into clearer focus down the road.

The scientists used the HARPS instrument on the European Southern Observatory's 3.6-meter telescope at the La Silla Observatory in Chile to study the spectrum of visible light reflected off the exoplanet 51 Pegasi b, which lies about 50 light-years from Earth in the constellation Pegasus.

51 Pegasi b, a "hot Jupiter" gas giant that orbits close to its parent star, was spotted in 1995, when it became the first alien world ever discovered around a sunlike star. (The first exoplanets of any type were found in 1992 around a superdense, rotating stellar corpse called a pulsar.)

Researchers most often study exoplanet atmospheres by analyzing the starlight that passes through them when worlds cross their stars' faces from Earth's perspective. This method, known as transit spectroscopy, is restricted to use on systems in which the stars and planets align.

The new strategy used with 51 Pegasi b, on the other hand, does not depend on planetary transits and could thus find broader applicability, researchers said.

The technique offers other scientific advantages as well.

“This type of detection technique is of great scientific importance, as it allows us to measure the planet’s real mass and orbital inclination, which is essential to more fully understand the system," study lead author Jorge Martins, of the Instituto de Astrofísica e Ciências do Espaço (IA) and the Universidade do Porto in Portugal, said in a statement.

"It also allows us to estimate the planet’s reflectivity, or albedo, which can be used to infer the composition of both the planet’s surface and atmosphere," Martins added.

The new data suggest that 51 Pegasi b is highly reflective, a bit larger in diameter than Jupiter and about half as massive as our solar system's biggest planet, researchers said.

Read more at Discovery News

Apr 21, 2015

Beaver Knocks Down Tree, Thousands Lose Power

A beaver in Maine's northern Aroostook County was doing what beavers do on Monday night — and chewed down a tree to help build its dam.

The problem is the tree happened to fall on a power transmission line and soon nearly 3,000 residents were out of power, according to a spokesman for the power company, Emera Maine.

"(The downed tree) is in a very remote, wooded area which has been challenging to reach, but workers will remain working to restore power by mid-morning," Bob Potts, spokesperson for Emera, told the Bangor Daily News.

Beavers are known for their impressive construction skills — building dams on rivers and streams, and building their homes in the resulting pond. They use their powerful front teeth to cut down trees for their construction projects.

While beavers tend to enhance their surrounding habitats, making them swampy havens for other wildlife, occasionally their work clashes with human-made systems. The rodents have been known to block irrigation, cause flooding on roads and fields — and knock down power lines.

As often-cited W.T. Cox wrote in a 1940 article in American Forest, "Beavers do not belong in thickly-settled communities, since their flooding operations may become troublesome...In the wild forest country, they do little harm and an immense amount of good."

From Discovery News

Homeopathic Products Under FDA Scrutiny

The Food and Drug Administration is re-examining its position on whether it should regulate homeopathic products, which are often sold alongside (and may be confused with) proven medications with active ingredients in pharmacies across the country.

In 1988 the FDA decided not to require that homeopathic remedies go through the same drug-approval process as standard medicines. Hearings began Monday in Washington and should the FDA decide that homeopathic products fall under its purview, manufacturers would need to prove that their products are safe and effective.

Homeopathy has been extensively studied, and researchers have concluded that it does not work.

In 2010 the British Science and Technology Select Committee conducted an examination of whether homeopathy has any medical or scientific validity; its report concluded that “there is no evidence that homeopathy works beyond the placebo effect (where a patient gets better because of their belief in the treatment).”

Australia’s National Health and Medical Research Council also investigated the effectiveness of homeopathy in a report released last month. It, too, reached the same damning conclusion: “there are no health conditions for which there is reliable evidence that homeopathy is effective.”

According to an article in the “Washington Post” while homeopathy advocates defend their practice, some welcome the proposed FDA oversight. “Ronald Whitmont, a homeopathic doctor in New York and president of the American Institute of Homeopathy, said his organization supports the FDA’s actions to crack down on poor manufacturing practices. ‘There are always bad apples in the manufacturing world, and they need to be policed just like in any other industry,’ he said. ‘We are behind the FDA. Their concern is our concern.’”

Whitmont added that he hoped that the FDA would not end up questioning the legitimacy of homeopathy’s practices or principles. One homeopathic practitioner even claimed in 2012 that homeopathic products could be used to somehow treat and prevent domestic violence.

Earlier this month the Canadian government took similar steps toward regulating homeopathy in the province of Ontario. A new law, the Ontario Homeopathy Act, provides a mechanism for homeopaths to self-regulate in a similar manner to doctors and nurses. Critics of the law, however, expressed concern that the effect would be to legitimize “the health-care equivalent of dowsing rods.”

Among those who testified in favor of the FDA revising its position was Michael De Dora, Director of Public Policy for the Center for Inquiry, a non-profit educational organization dedicated to evidence-based public policy. “I think the FDA is finally revisiting the issue of regulating homeopathy because of several troubling and prominent cases related to homeopathy,” De Dora told Discovery News. “In 2010, there was a situation in which homeopathic products for teething children containing too much belladonna put several kids in the hospital.

More recently, homeopaths have been claiming to own cures for everything from asthma to more pressing public health issues, such as Ebola which has prompted to FDA to write letters and issue consumer warnings.

Still, perhaps the greatest harm caused by homeopathy is not necessarily caused by the products themselves—which, when properly prepared, rarely contain anything other than water and inactive ingredients such as sugars and binding agents—but by the fact that people often rely on homeopathic products to the exclusion of proven scientific remedies.”

Following his testimony De Dora said he was “encouraged by the critical questions the FDA panel posed. The FDA would have never held this hearing if they didn’t have some inclination to regulate homeopathy.

Read more at Discovery News

Were Neanderthals Doomed by Lack of Fire Mastery?

Neanderthals may have died off because they failed to harness the power of fire to the extent their human cousins did, a new data analysis suggests.

Using fire for cooking would have allowed these other groups of ancient human relatives to get more calories from the same amount of food, thereby edging out the Neanderthal population. Over time, the anatomically modern human population would have risen, while the Neanderthal population plummeted toward extinction, according to the model.

"Fire use would have provided a significant advantage for the human population and may indeed have been an important factor in the overall collapse or absorption of the Neanderthal population," said Anna Goldfield, a doctoral candidate in archaeology at Boston University, who presented the findings here on Thursday (April 16) at the 80th Annual Meeting of the Society for American Archaeology.

Mysterious disappearance

One of the enduring mysteries of human history is why the Neanderthals went extinct in most of Europe around 40,000 years ago. Neanderthals had been living on the continent for hundreds of thousands of years when the first modern humans showed up about 45,000 years ago, Goldfield said. Then, in a relatively short span of time, the Neanderthals vanished.

"The arrival of humans had something to do with the extinction of Neanderthals," Goldfield told Live Science.

But the exact cause has been a matter of hot debate. Some have postulated that Neanderthals found it increasingly difficult to access resources they needed given their small group sizes and relatively local trading networks. Other scientists have even proposed that humans cannibalized their Neanderthal rivals.

"The issue of Neanderthal extinction is very complex, and very little is agreed upon," Goldfield said.

Goldfield and her colleague Ross Booton, a mathematical biologist at the University of Sheffield in the United Kingdom, wondered whether fire use had something to do with the demise, they said.

One big difference between the Neanderthals and humans may have been modern humans' mastery of fire. Not only can it provide warmth, but fire also enables people to cook their food. This can kill bacteria, making food safer, and denature proteins, meaning the body can harness more calories from the same amount of food. In addition, Neanderthals may have required more calories to survive in the first place because they had higher average body mass. Thus, modern humans' lower food needs could have given them a decisive edge in the cold, nutritionally sparse environment of Western Europe at the time, Goldfield said.

While some fossil sites suggest Neanderthals used fire, they may not have used it often or consistently. For instance, Neanderthals occupied two sites in southwest France — Roc de Marsal, and Pech de l'Aze IV — for tens of thousands of years. The sites contain tens of thousands of stone tools and animal bones, but almost no evidence of fire making, said Dennis Sandgathe, an archaeologist at Simon Fraser University who has excavated the sites.

"The Neanderthals are somehow just getting by without fire," Sandgathe told Live Science.

Competing resources

To understand the effects of fire use on Neanderthals, the researchers used mathematical models. The simulations helped estimate how the populations of anatomically modern humans and Neanderthals changed when humans were using fire more frequently than Neanderthals, or when both groups used fire about equally. The researchers also looked at the population of reindeer, which both groups ate, under those scenarios.

The numbers showed that the more that modern humans used fire relative to their Neanderthal cousins, the more likely the human population was to increase slightly. That, in turn, would have reduced the number of reindeer available for the Neanderthals to eat. Over time, the human population would have simply outcompeted the Neanderthals for resources, leading to this population's eventual demise.

Read more at Discovery News

Venus and Moon to Snuggle Up as Dazzling Duo Tonight

This evening will be another one of those special occasions when the two brightest objects in the night sky — the moon and a Venus — will get together and, weather permitting, will attract a lot of attention, even to those who normally do not spend much time in gazing up at the sky.

If your local weather is clear tonight (April 21), you're in for a celestial treat. Turn to face west about 45 minutes after sunset, during mid-twilight, and you should see a beautiful crescent moon and floating well off to its right is the dazzling evening star: the planet Venus.

And as the night gets darker, you might take note of another object, much dimmer than Venus, located to the lower right of the moon at roughly half the distance separating the moon and Venus. Shining with a distinct orange color, it's the 1st-magnitude star Aldebaran in the constellation of Taurus, the Bull.

Venus is the one object has been calling attention to itself as soon as the sun has slipped below the horizon. It currently dazzles in the western sky, about one-third of the way up from the horizon to the overhead point. Predictably, I've gotten quite a few inquiries about it in recent days. Typically they've gone something like this:

"I was out walking last week and was sure I saw a U.F.O.  Was there anything unusual going on in the sky last week?  Is there anything that could explain this 'sighting'?"

Venus is Staying Up Late

Some folks are rather surprised when I tell them that Venus has been an evening object since mid-December. In at least two instances, I've had conversations with people who staunchly claimed that "Venus wasn't there just a week ago!" and that this is the first time that they've caught sight of it.

Of course, earlier in the year, Venus was considerably lower in the west-southwest sky, and setting much earlier in the evening (before 7 p.m. your local time). But now that we are more than a month into spring, with many states (save for Arizona and Hawaii) observing Daylight Saving Time, the viewing circumstances for Venus have changed for the better. Venus is now setting at around 11:15 p.m. local time for most observers.

But the best is yet to come!

On May 10, Venus will attain its highest declination: 26 degrees north of the celestial equator. Less than a month later, on June 6, it reaches its greatest eastern elongation (greatest angular distance east) of the sun of 45 degrees.

Roughly midway between these two extremes, for about two weeks beginning on May 17, Venus will be at the pinnacle of its current evening apparition. It will then be setting more than three and a half hours after local sunset. For New York City, for example, that corresponds to 11:44 p.m. EDT.

Read more at Discovery News

Apr 20, 2015

Sex at Nearly 10,000 Feet Below Ocean's Surface

Sex at close to 10,000 feet below the ocean’s surface happens slowly but frequently for at least some denizens of the deep.

Since these creatures — vampire squid — mate at a different pace than other squid and their related species do, a new study reveals how unique reproductive strategies can be at tremendous ocean depths.

The new study is published in the latest issue of the journal Current Biology.

“We know very little about deep-sea organisms and their life-cycle patterns, in particular in the water column of the deep sea,” lead author Henk-Jan Hoving of the GEOMAR Helmholtz Center for Ocean Research Kiel said in a press release. “The patterns we know from coastal and shallow-water organisms may not apply to deep-sea species.”

Vampire squid got their name, not because they feast on blood, but because of their big red eyes and darkly colored cloak-like webbing.

Hoving and his team were going through the vampire squid collections from the 60s and 70s at the Santa Barbara Museum of Natural History, when they noticed something unexpected.

Many of the female vampire squid had spawned, but they had no ripe or developing eggs and were in a reproductive resting phase. This is unheard of for other squid, which reproduce all at once late in their lives and that’s it.

Here is video showing how another squid species, Pholidoteuthis adami from the Gulf of Mexico, mates:

The researchers also investigated female vampire squid. One had released at least 3,800 eggs, yet still retained 6,500 viable oocytes (immature reproductive cells) for future spawning. Assuming an average batch size of 100 eggs, the researchers suggest that this one female had already spawned about 38 times, with eggs in reserve for another 65 or so spawning episodes.

That means vampire squid could have about 100 times more sex than other squid do!

Life at incredible ocean depths goes at a slow pace, however. Vampire squid don’t swim so much as float. They also must survive with very little oxygen, and their diet is a very low calorie one, since they mostly eat zooplankton and organic debris.

Read more at Discovery News

Evidence of Pre-Columbus Trade Found in Alaska

Bronze artifacts discovered in a 1,000-year-old house in Alaska suggest trade was occurring between East Asia and the New World centuries before the voyages of Columbus.

Archaeologists found the artifacts at the “Rising Whale” site at Cape Espenberg.

“When you’re looking at the site from a little ways away, it looks like a bowhead coming to the surface,” said Owen Mason, a research associate at the University of Colorado, who is part of a team excavating the site.

The new discoveries, combined with other finds made over the past 100 years, suggest trade items and ideas were reaching Alaska from East Asian civilizations well before Christopher Columbus arrived in the Caribbean Sea in 1492 archaeologists said.

“We’re seeing the interactions, indirect as they are, with these so-called ‘high civilizations’ of China, Korea or Yakutia,” a region in Russia, Mason said.

Bronze and obsidian

The Rising Whale discoveries include two bronze artifacts, one of which may have originally been used as a buckle or fastener. It has a piece of leather on it thatradiocarbondates to around A.D. 600 (more tests will take place in the future). The other bronze artifact may have been used as a whistle.

Bronze-working had not been developed at this time in Alaska, so archaeologists think the artifacts would have been manufactured in China, Korea or Yakutia, and made their way to Alaska through trade routes.

Also inside that house, researchers found the remains of obsidian artifacts, which have a chemical signature that indicates the obsidian is from the Anadyr River valley in Russia.

Trade routes

The recent discoveries at the Rising Whale site add to over a century of research that indicates trade routes connected the Bering Strait (including the Alaskan side) with the civilizations that flourished in East Asia before Columbus’ time.

In 1913, anthropologist Berthold Laufer published an analysis of texts and artifacts in the journal T’oung Pao in which he found that the Chinese had a great interest in obtaining ivory from narwhals and walruses, acquiring it from people who lived to the northeast of China. Some of the walrus ivory may have come from the Bering Strait, where the animals are found in abundance.

Additionally, a number of researchers have noted similarities in design between the plate armor worn by people in Alaska and that worn in China, Korea, Japan and eastern Mongolia.

For instance, in the 1930s, Smithsonian Institution archaeologist Henry Collins undertook excavations at St. Lawrence Island, off the west coast of Alaska. In his book “The Archaeology of St. Lawrence Island” (Smithsonian, 1937), he wrote that plate armor started appearing on the island around 1,000 years ago. It consisted of overlapping plates made of ivory, bones and sometimes iron.

Plate armor similar to this was developed in several areas of East Asia, including Manchuria (in China), eastern Mongolia and Japan, Collins wrote. The use of plate armor, he said, spread north from these areas, and was eventually introduced to Alaska from across the Bering Strait.

Genetic evidence

Recent genetic research also sheds light on interactions between people from East Asia and the New World.

Many scientists say that humans first arrived in the New World around 15,000 years ago by crossing a land bridge that had formed across the Bering Strait. This land bridge was flooded about 10,000 years ago.

However, a recent genetic study suggests there were also movements of people from East Asia to the New World at a later date. Those who lived at the Rising Whale site may be part of what scientists refer to as the “Birnirk” culture, a group of people who lived on both sides of the Bering Strait and used sophisticated skin boats and harpoons to hunt whales.

The genetic study indicates that people from the Birnirk culture are the ancestors of a people called the “Thule,” who spread out across the North American arctic as far as Greenland. The Thule, in turn, are ancestors of the modern-day Inuit.

Long before Columbus

The Bering Strait wasn’t the only area where interactions between people from the Old World and New World occurred before Columbus’ arrival. By 1,000 years ago, the Vikings had explored parts of Canada and had even established a short-lived settlement at L’Anse aux Meadows in Newfoundland.

Research also indicates that, around this time, the Polynesians had reached South America, bringing sweet potatoes back to Polynesia and possibly bringing chickens to South America.

Read more at Discovery News

Coast Guard Aircraft Spots 100-Year-Old Shipwrecks

A helicopter from the U.S. Coast Guard’s Traverse City, Mich. station was on a routine patrol mission over northern Lake Michigan Friday, when crew members noticed a chilling sight.

Beneath the crystal clear waters of the lake — now free of ice, but still just above freezing — they could see the wreckage of numerous lost ships on the lake bottom. They took a series of photos and posted them to the station’s Facebook page, and invited local historical buffs to help them identify the wrecks.

One of the wrecks turned out to be a century and a half old. The James McBride, a 121-foot brig  was launched on April Fools Day 1848. On Oct. 19, 1857, the ship was transporting a cargo of wood from the Manitou Islands to Chicago, when she encountered a gale and was driven aground, and then abandoned as a total loss.

Another of the wrecks was the Rising Sun, a 133-foot-long wooden steamer that met its demise on Oct. 29, 1917. The ship broke up, and the remains now sit in 6 to 12 feet of water.

According to an article by local historian George Weeks, the Rising Sun was headed to High Island to get a load of potatoes, rutabagas and lumber, when it was caught in a winter storm. The crew attempted to reach the shore, but one of the ship’s anchors failed to hold and then became caught in a place where each wave that crashed into the ship slammed it into the lake bottom. The captain and four of the ship’s six sailors were swept away to their deaths. The two survivors managed to hang on and survive though the night.

The next morning, a man named Charles Rosman — son of a Great Lakes ship captain –was taking a walk along the beach when he saw the Rising Sun’s broken decks, which were covered with ice, and heard the cries of the surviving sailors. He quickly roused a half-dozen other local men, who used a horse-drawn sleigh to haul a small fishing boat to the beach, and then braved the rough, ice-cold waters to reach the disintegrating vessel and rescue the two sailors. The U.S. government later awarded them a medal for their efforts.

Read more at Discovery News

Mysterious 'Cold Spot': Fingerprint of Largest Structure in the Universe?

At the furthest-most reaches of the observable universe lies one of the most enigmatic mysteries of modern cosmology: the cosmic microwave background (CMB) Cold Spot.

Discovered in 2004, this strange feature etched into the primordial echo of the Big Bang has been the focus of many hypotheses — could it be the presence of another universe? Or is it just instrumental error? Now, astronomers may have acquired strong evidence as to the Cold Spot’s origin and, perhaps unsurprisingly, no multiverse hypothesis is required. But it’s not instrumental error either.

When the Cold Spot was first revealed by NASA’s Wilkinson Microwave Anisotropy Probe (WMAP), astronomers quickly realized that the feature, if real, would be the largest structure ever seen in the cosmos. But with just one space telescope providing the measurements, there was always the concern that something mundane — like instrumental error — could be to blame.

Then the European Planck telescope, that was also launched to measure slight temperature variations in the CMB (known as anisotropies), also saw the Cold Spot. Despite some theories that the feature may actually be an error caused by our statistical analysis methods, it was generally thought that the Cold Spot was real.

One of the most extreme (and, frankly, exciting) hypotheses possibly explaining the Cold Spot focused around the multiverse. Stemming from superstring theory, the multiverse posits that our universe is just one of many universes in a bubbly soup of universes (universi?). And that Cold Spot? Well, it could be one of those neighboring universes nuzzling up against our own.

As I outlined in a recent DNews video, the multiverse hypothesis is certainly one of the more extreme cosmological ideas out there and other explanations for the Cold Spot exist. And one idea that now appears to have gained some meat is that of the existence of a “supervoid” in the universe between us and the Cold Spot imprint in the CMB.

Through the combination of observational data from Hawaii’s Pan-STARRS1 (PS1) telescope located on Haleakala, Maui, and NASA’s Wide Field Survey Explorer (WISE) satellite, István Szapudi of the Institute for Astronomy at the University of Hawaii at Manoa and his collaborators may have found “the largest individual structure ever identified by humanity” and this structure may be creating the anomalous Cold Spot.

Previous studies have shown that there is little evidence for a very distant structure in the direction of the Cold Spot. But, paridoxically, it is harder to identify large structures that are closer to us than further away. By constructing a 3-D map of galaxies, the researchers discovered a vast region, only 3 billion light-years away (that’s close in the grand cosmological scheme of things), that has a lower density of galaxies than the rest of the known universe. This supervoid is huge, measuring about 1.8 billion light-years wide. This vast supervoid could therefore be the largest structure ever identified by humanity.

So Szapudi’s team may have identified a vast supervoid in space, what’s that got to do with the CMB Cold Spot?

The radiation from the CMB is the most ancient form of radiation known in the universe. Created just after the Big Bang nearly 14 billion years ago, this weak glow has to travel from the most distant edge of our observable universe to be detected by our instrumentation. The medium that this radiation travels through is therefore very important.

As the CMB radiation encountered the supervoid, a region of space with a density much lower than the rest of the universe, the Integrated Sachs-Wolfe (ISW) effect may have altered the characteristics of any radiation traveling through it. As the universe is expanding, the radiation traveling through the supervoid will lose more energy than radiation traveling though ‘normal’ space, creating an anomalously cool imprint in the WMAP and Plank anisotrophy maps. This imprint would manifest itself as a huge Cold Spot.

Read more at Discovery News

Apr 19, 2015

Dating the moon-forming impact event with meteorites

Through a combination of data analysis and numerical modeling work, researchers have found a record of the ancient Moon-forming giant impact observable in stony meteorites. Their work will appear in the April 2015 issue of the Journal Science. The work was done by NASA Solar System Exploration Research Virtual Institute (SSERVI) researchers led by Principal Investigator Bill Bottke of the Institute for the Science of Exploration Targets (ISET) team at the Southwest Research Institute and included Tim Swindle, director of the University of Arizona's Lunar and Planetary Laboratory.

The inner Solar System's biggest known collision was the Moon-forming giant impact between a large protoplanet and the proto-Earth. The timing of this giant impact, however, is uncertain, with the ages of the most ancient lunar samples returned by the Apollo astronauts still being debated. Numerical simulations of the giant impact indicate this event not only created a disk of debris near Earth that formed the Moon, but it also ejected huge amounts of debris completely out of the Earth-Moon system. The fate of this material, comprising as much as several percent of an Earth mass, has not been closely examined until recently. However, it is likely some of it blasted main belt asteroids, with a record plausibly left behind in their near-surface rocks. Collisions on these asteroids in more recent times delivered these shocked remnants to Earth, which scientists have now used to date the age of the Moon.

The research indicates numerous kilometer-sized fragments from the giant impact struck main belt asteroids at much higher velocities than typical main belt collisions, heating the surface and leaving behind a permanent record of the impact event. Evidence that the giant impact produced a large number of kilometer-sized fragments can be inferred from laboratory and numerical impact experiments, the ancient lunar impact record itself, and the numbers and sizes of fragments produced by major main belt asteroid collisions.

Once the team concluded that pieces of the Moon-forming impact hit main belt asteroids and left a record of shock heating events in some meteorites, they set out to deduce both the timing and the relative magnitude of the bombardment. By modeling the evolution of giant impact debris over time and fitting the results to ancient impact heat signatures in stony meteorites, the team was able to infer the Moon formed about 4.47 billion years ago, in agreement with many previous estimates. The most ancient Solar System materials found in meteorites are about one hundred million years older than this age.

Insights into the last stages of planet formation in the inner solar system can be gleaned from these impact signatures. For example, the team is exploring how they can be used to place new constraints on how many asteroid-like bodies still existed in the inner Solar System in the aftermath of planet formation. They can also help researchers deduce the earliest bombardment history of ancient bodies like Vesta, one of the targets of NASA's Dawn mission and a main belt asteroid whose fragments were delivered to Earth in the form of meteorites. It is even possible that tiny remnants of the Moon-forming impactor or proto-Earth might still be found within meteorites that show signs of shock heating by giant impact debris. This would allow scientists to explore for the first time the unknown primordial nature of our homeworld.

Co-author Swindle, who specializes in finding the times when meteorites or lunar samples were involved in large collisions, said: "Bill Bottke had the idea of looking at the asteroid belt to see what effect a Moon-forming giant impact would have, and realized that you would expect a lot of collisions in the period shortly after that.

"Here at LPL, we had been determining ages of impact events that affected meteorites, and when we got together, we found that our data matched his predictions," he added. "It's a great example of taking advantage of groups that work in two different specialties -- orbital dynamics and chronology -- and combining their expertise."

Intriguingly, some debris may have also returned to hit the Earth and Moon after remaining in solar orbit over timescales ranging from tens of thousands of years to 400 million years.

Read more at Science Daily

Repeated marine predator evolution tracks changes in ancient and Anthropocene oceans

For more than 250 million years, four-limbed land animals known as tetrapods have repeatedly conquered the Earth's oceans. These creatures--such as plesiosaurs, penguins and sea turtles--descended from separate groups of terrestrial vertebrates that convergently evolved to thrive in aquatic environments.

In a new scientific review, a team of Smithsonian scientists synthesized decades of scientific discoveries to illuminate the common and unique patterns driving the extraordinary transitions that whales, dolphins, seals and other species underwent as they moved from land to sea. Drawing on recent breakthroughs in diverse fields such as paleontology, molecular biology and conservation ecology, their findings offer a comprehensive look at how life in the ocean has responded to environmental change over time. The paper also highlights how evolutionary history informs an understanding of the impact of human activities on marine species today. More information is available in the April 17 issue of Science.

Marine tetrapods represent a diverse group of living and extinct species of mammals, reptiles, amphibians and birds that all play--or played--a critical role as large ocean predators in marine ecosystems. The repeated transitions between land and sea have driven innovation, convergence and diversification against a backdrop of changing marine ecosystems and mass extinctions dating back to the Triassic period. In this way, they provide ideal models for testing hypotheses about the evolution of species over long periods of time. Modern species of marine tetrapods now face a suite of human-driven impacts to their environment, including climate change, habitat degradation, ship collisions and underwater noise.

"We know from the fossil record that previous times of profound change in the oceans were important turning points in the evolutionary history of marine species," said Neil Kelley, a Peter Buck post-doctoral researcher in the National Museum of Natural History's department of paleobiology and lead author in the study. "Today's oceans continue to change, largely from human activities. This paper provides the evolutionary context for understanding how living species of marine predators will evolve and adapt to life in the Anthropocene."

Recent investigations in the fossil record have provided new insight into the evolution of traits that allowed marine tetrapods to thrive in the sea. In some cases, similar anatomy evolved among lineages that adapted to marine lifestyles. For example, modern dolphins and extinct marine reptiles called ichthyosaurs descended from distinct terrestrial species, but independently converged on an extremely similar fish-like body plan although they were separated in time by more than 50 million years. The repeated transformation of legs adapted for walking on land into fins is another classic example of convergent evolution. Species ranging from seals to mosasaurs independently developed streamlined forelimbs as they transitioned from living on land to the ocean, allowing them to move quickly and efficiently in the water. This transformation may have been achieved by parallel changes at the genome level.

"Land to sea transitions have happened dozens of times among reptiles, mammals and birds, across major mass extinctions," said Nicholas Pyenson, the museum's curator of fossil marine mammals. "You often get similar looking results but convergence is more than skin deep. It can be seen on a broad range of scales, from molecules to food webs, over hundreds of millions of years."

In the case of deep divers such as beaked whales and seals, these species have independently evolved to have positively charged oxygen-binding proteins called myoglobin in their muscles, allowing them to survive underwater for long periods of time. Scientists also have found identical genetic sequences in different marine species, such as whales, seals and sea cows. Whether these invisible molecular similarities account for larger-scale visible patterns of convergent evolution, or whether convergent anatomy follows different genetic pathways in different groups, remains an important open question to be tackled as genomic sequences become available for more species.

Read more at Science Daily