Some migratory birds that have to navigate across continents have an extremely useful tool at their disposal–an internal compass that points unerringly towards magnetic north. Researchers already knew that some birds possess these biological compasses, but their mechanism has been unclear. “This is basically the sixth sense of biology, but no one knows how it works…. The magnetic sense is by far the least understood sense in the natural world,” [Science News], says study coauthor Henrik Mouritsen.
Now, researchers have determined that light-sensing cells in the eye convey the crucial message to a special visual center of a robin’s brain, called cluster N. Special proteins called cryptochromes in the birds’ eyes may mediate this light-dependent magnetic sensing, Mouritsen says. Light hitting the proteins produces a pair of free radicals, highly reactive molecules with unpaired electrons. These electrons have a property called spin which may be sensitive to Earth’s magnetic field. Signals from the free radicals may then move to nerve cells in cluster N, ultimately telling the birds where north is [Science News].
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To zero in on air pollution, just follow the magnetic tree leaves.
That’s the conclusion of an odd new study, which determined that the microscopic metallic particles spewed out of tailpipes and smokestacks actually magnetize the nearby leaves they settle on and adhere to. The study found that the leaves from trees along heavily traveled bus routes were up to 10 times more magnetic than leaves from little traveled roads. The pollution can be detected easily and on the cheap with magnets, according to the study’s authors. Even “a strong magnet wouldn’t [attract] the leaf, but it definitely gives you a detectable signal” [National Geographic News], says researcher Bernie Housen.
The authors admit that finding more pollution along bus routes isn’t exactly shocking, but their efforts may help local communities pinpoint and clean up places that have an abundance of air pollution, especially at places where people spend time outdoors, like on bike trails and walking paths. The research team says that using magnets would be an advance in pollution detection because conventional tests for measuring the amounts of these tiny particles are often expensive and time-consuming [National Geographic News]. The study was presented at the Geological Society of America conference in Portland, Oregon.
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Mix one part science fiction, one part misunderstood Mayan history, one part Hollywood movie hype, and quite a bit of public credulity, and what do you get? A new wave of doomsday hysteria that is causing scientists to step forward to reassure the public that the world is not, actually, going to end on December 21, 2012.
The rumors flying around the Internet offer a number of ways in which the world may end, including a planetary collision and changes to the Earth’s rotation or magnetic field, but they all agree on that date of doom. You can bet that the viral marketing campaign promoting the upcoming planetary disaster movie 2012 has a little something to do with the recent uptick in paranoia.
“Two years ago, I got a question a week about it,” said NASA scientist David Morrison, who hosts a website called Ask an Astrobiologist. “Now I’m getting a dozen a day. Two teenagers said they didn’t want to see the end of the world so they were thinking of ending their lives” [Los Angeles Times]. In response, Morrison put together a list [pdf] of 10 frequently asked questions about the potential for apocalypse, and refuted them one by one. The clamor has grown so loud that Morrison coined a new word to describe the phenomenon: “cosmophobia,” a fear of the cosmos.
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Magnets may have seemed simple when you learned about them in elementary school, but physicists are coaxing some very odd behaviors out of magnetic materials these days. In the latest new development, scientists created the magnetic equivalent of electricity and named the phenomenon “magnetricity.” In the same way that electrically charged particles flow to create an electric current, individual north and south magnetic poles have been observed flowing along to generate a magnetic current.
The basis of the experiment was a refutation of a rule of magnetism observed in our day-to-day lives: No matter how many times you divide a magnet, the resulting fragments will always have both north and south poles. But more than 70 years ago, physicist Paul Dirac theorized that elementary particles should exist that have only a north or south pole, and dubbed these theoretical particles magnetic monopoles. Last month, researchers got closer to spotting a monopole than ever before, when they created ripples that had the same magnetic properties as monopoles.
The new study, published in Nature, describes the phenomenon in a strange, crystalline material known as spin ice. These crystals are made up of pyramids of charged atoms, or ions, arranged in such a way that when cooled to exceptionally low temperatures, the materials show tiny, discrete packets of magnetic charge. Now one of those teams has gone on to show that these “quasi-particles” of magnetic charge can move together, forming a magnetic current just like the electric current formed by moving electrons [BBC News].
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In an experiment that might be classified more as a cool party trick than a scientific breakthrough, researchers levitated a mouse using a powerful superconducting magnet. Other scientists have previously levitated frogs and bugs using the same technique, but the floating mouse was the first mammal to have the honor. The trick works because the magnet generates a strong magnetic field, and because the water in the mouse’s body is weakly diamagnetic–it generates a magnetic field of its own that pushes back against the external field. Since the researchers had a strong enough magnet, the repulsive force generated by the water in each mouse cell combined to make its whole body float.
The researchers used a tiny three-week-old mouse that was only as heavy as a stack of four pennies. When the scientists levitated the youngster it appeared agitated and disoriented, seemingly trying to hold on to something. “It actually kicked around and started to spin, and without friction, it could spin faster and faster, and we think that made it even more disoriented,” said researcher Yuanming Liu…. They decided to mildly sedate the next mouse they levitated, which seemed content with floating [LiveScience].
The technique will be a boon for space research, the scientists say. “We’re trying to see what kind of physiological impact is due to prolonged microgravity, and also what kind of countermeasures might work against it for astronauts,” Liu said. “If we can contribute to the future human exploration of space, that would be very exciting” [LiveScience].
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Physicists can come off like monster hunters sometimes–their theories predict that a rare beast lurks in the atomic-scale underbrush, so they forge on against all odds, determined to catch a glimpse of their quarry. The latest target is the magnetic monopole, and researchers say they’ve come closer than ever before to spotting it.
Every magnet has a north and a south pole; if you break a magnet into hundreds of pieces, each fragment will also have a north and a south pole of its own. But researchers think that magnetic monopoles exist–particles with only a north or south pole–and there are several reasons physicists would like to see them. In 1931, famed British theorist Paul Dirac argued that the existence of monopoles would explain the quantization of electric charge: the fact that every electron has exactly the same charge and exactly the opposite charge of every proton [ScienceNOW Daily News].
Scientists have scoured the world and the cosmos looking for such particles, says Jonathan Morris, coauthor of one of the two new studies published in Science. “People have been looking for monopoles in cosmic rays and particle accelerators — even Moon rocks” [Nature News], he says. And while the two research groups didn’t quite find the elusive particles, they did detect ripples in strange materials known as spin ices, and found that the ripples have the same magnetic properties as monopoles.
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When the Messenger spacecraft swooped low past the planet Mercury on October 6 2008, it gathered up a wealth of data that will have planetary scientists puzzling for years. As researchers sort through findings regarding Mercury’s volcanic past, meteor impacts, and the effect of the solar wind on the innermost planet’s magnetosphere, one broad conclusion stands out: Mercury isn’t just a boring chunk of rock. Marilyn Lindstrom, a NASA program scientist, said the Messenger findings show that Mercury is “just an amazingly dynamic planet, both in the past and in the present” [Baltimore Sun].
Superficially, Mercury looks a lot like the moon: small, grayish-brown and pockmarked with craters. Some scientists assumed that Mercury’s surface formed the same way the moon’s did, with lighter rocks rising to the surface of a magma ocean and congealing into a brittle crust early on. But the new observations reveal that 40 percent of the surface was formed by volcanoes. “Up until before Messenger’s arrival, we weren’t even sure that volcanism existed on Mercury” [Wired], says researcher Brett Denevi. The presence of titanium oxide also suggests that the planet was hot enough in its first 100 million years to be covered in magma oceans.
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Thanks to a quintet of satellites and a backup posse of ground-based telescopes, researchers have gotten their best look ever at how auroras–also known as the southern and northern lights–begin to form in space. The dazzling light displays are provoked by “space tornadoes,” researchers say.
Whirling at more than a million miles per hour, these invisible, funnel-shaped solar windstorms carry electrical currents of more than a hundred thousand amps—roughly ten times that of an average lightning strike—scientists announced…. And they’re huge: up to 44,000 miles (70,000 kilometers) long and wide enough to envelop Earth [National Geographic News].
The observations were made as part of NASA’s THEMIS mission, which uses the satellites and telescopes to study how solar winds, the charged particles that stream from the sun, interact with the Earth’s magnetic field. On the Earth’s dark side, the solar wind stretches out the field, forming a region known as the magnetotail. The magnetotail is like a rubber band; when it is stretched too far, “eventually it snaps and releases the energy”, says team member Andreas Keiling [New Scientist]. That snap creates turbulence and forms the tornadoes, researchers announced at the European Geosciences Union meeting.
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A tiny moon rock only two inches across that was picked up by one of the last astronauts to walk on the moon has given researchers new insight into the geological history of Earth’s satellite. The rock, scooped up during the Apollo 17 mission in 1972, is about 4.2 billion years old, and shows evidence that the moon once had a molten iron core that generated a magnetic field in the satellite’s early days. The findings are forcing researchers to rethink the prevailing notion that objects smaller than Mars can’t maintain a stable magnetic field.
Many of the rocks brought back from the Moon have a faint magnetic signal, suggesting that they originally cooled from magma when the Moon had a magnetic field. That was a surprise to many scientists who thought the Moon was too small and too cold to have ever possessed a geomagnetic dynamo where electric currents from the convection of molten iron generate a field [The New York Times]. But a molten core wasn’t the only explanation for the magnetic traces; some researchers thought that an intense bombardment of meteorites and asteroids created shocks that magnetized the rocks.
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The magnetic field that surrounds our planet and protects us from the sun’s harmful radiation sometimes springs a couple of large leaks that let in blasts of solar wind, researchers have discovered. While humanity isn’t in any imminent danger, researchers say that during intense solar storms the rents in what’s known as the magnetosphere will let in streams of charged solar particles, which can interfere with satellites and electricity grids.
Researchers knew previously that cracks in the magnetosphere sometimes occur, but they didn’t understand their potential size and had some misunderstandings about how they formed. Previously, scientists believed that the holes form when the sun’s magnetic field is aligned in the opposite direction from the Earth’s. But the new study showed that 20 times more solar particles enter the Earth’s magnetic field when it is aligned in the same direction as the sun’s magnetic field. The alignment causes the two magnetic fields to connect and tears holes in the Earth’s magnetic field over the poles. “What we observed was the breach in the levee,” said Jimmy Raeder, a physicist at the University of New Hampshire. “This has taken us completely by surprise” [Reuters].
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It’s a question that has fascinated scientists for decades: When sea turtles and salmon decides to give up the freedom of the open ocean and head back to their birthplaces to breed, how do they find their way back? Some species of sea turtle migrate thousands of miles across entire oceans back to their birthplaces after leaving more than 10 years earlier. And after hatching in rivers, salmon travel hundreds of miles out to sea before returning home to spawn years later [Press Association]. Now one researcher thinks he has the answer. Marine biologist Kenneth Lohmann believes that these marine animals can detect the distinctive magnetic fields of different spots and use them to navigate.
“What we’re proposing is the sea turtles and salmon, when they begin life, basically learn or imprint on the magnetic field that marks their home area,” he said. “They retain this information. And years later, when it is time for them to return, they are able to exploit this information in navigating back to their home area” [National Geographic News]. Lohman says this doesn’t contradict the existing theory that when salmon reach coastal waters, chemical scents guide them upriver to the particular stream where they were born; those olfactory cues probably have a limited range, he says, and couldn’t extend thousands of miles into the ocean to guide the salmon all the way home.
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Researchers have tested a small, portable magnetic field that could be just the protection required for a manned expedition to Mars, when astronauts would need to be protected from radiation from solar storms. Researchers say the lab experiment is the proof of concept for a magnetic force-field that mimics the protective qualities of the Earth’s magnetosphere, which shields our planet from that same radiation.
Outside Earth’s protective atmosphere and magnetic field, supersonic particles from stellar processes run amok, screaming through space and tearing through just about anything in their path—including the bodies of astronauts, where they can wreak havoc on genetic material [Scientific American]. Astronauts on the International Space Station are within Earth’s protective magnetic field, so the Apollo astronauts who went to the moon are the only humans who have been exposed to this radiation; happily, there were no major solar storms during their quick trips to the moon and back. However, a manned mission to Mars would take about six months each way, leaving astronauts much more vulnerable.
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In a stretch of the universe 6.5 billion light years away, astronomers have detected a young galaxy with a bizarrely strong magnetic field that is making them question the accepted theory of how galactic magnetic fields form. “This was a complete surprise,” said [lead researcher] Arthur Wolfe…. “The magnetic field we measured is at least an order of magnitude larger than the average value of the magnetic field detected in our own galaxy” [SPACE.com].
In the current dynamo theory of magnetic field formation, large galaxies develop strong magnetic fields through a slow and gradual process. Astrophysicists think these fields are slowly built up from smaller ’seed fields’ that surround the charged particles blasted out by supernovae. Over billions of years, the galaxies’ slow spin whips up these particles and acts like a dynamo to align and amplify the fields [New Scientist].
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NASA has announced that in 2014 a new spacecraft called MAVEN will settle into orbit around Mars, and will get to work trying to solve the mystery inherent in the thin atmosphere of the Red Planet. Mars once had a much denser atmosphere which allowed liquid water to swill across its surface, but much of the former went awol “as part of a dramatic climate change.” Doug McCuistion, director of the Mars Exploration Program, said: “The loss of Mars’ atmosphere has been an ongoing mystery. MAVEN will help us solve it” [The Register].
The $485 million mission will be led by a team from the University of Colorado. MAVEN (which stands for Mars Atmosphere and Volatile EvolutioN mission), will be the second mission of the space agency’s Mars Scout program, a recent push by the agency for smaller, lower-cost spacecraft. The first, the Phoenix, was launched in 2007 and is operating on the surface of Mars [Denver Post].
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Cattle and deer grazing in fields tend to align themselves with the Earth’s magnetic field, suggesting that the animals may have a built-in magnetic compass. A new study shows that animals in these herds tend to face towards either magnetic north or south, which has come as a surprise even to those who spend their days with bovines. Asked whether he had ever observed such behavior in cows, dairy farmer Rob Fletcher of Tulare, Calif., said, “Absolutely not.” But, he added, “I don’t spend a lot of time worrying about stuff like that” [Los Angeles Times].
Researchers used satellite imagery from Google Earth to look for patterns in more than 300 cow-filled pastures from every continent except Antarctica, and in more than 250 herds of deer in the Czech Republic. While every individual animal didn’t face the same direction, the herds, on average, pointed towards either magnetic north or south. That orientation didn’t consistently line up with any aspect of the terrain on which they were grazing, the direction from which the wind was blowing or the direction from which the sun was shining, [co-author Hynek] Burda says. In fact, many of these field observations were made at night, he notes [Science News].
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