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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In the heart of the Perseus galaxy cluster lies a remarkable galaxy known as NGC 1275, which has long “filaments”of glowing gas that snake out from its center. Astronomers have tried to explain how these beautiful structures can have survived for so long, given that the filaments reach out from their home galaxy into the Perseus cluster, which is a hostile, high-energy environment with a strong, tidal pull of gravity.These combined forces should have ripped apart the filaments in a very short time, causing them to collapse into stars [The Independent].
Now, thanks to images from the Hubble Space Telescope, astronomers say they understand how the filaments have held their shape for over 100 million years: Magnetic fields are keeping the filaments together, they say. The magnetic fields … hold onto the filaments because they wield influence over charged particles – such as protons and electrons – in the filaments’ gas [New Scientist].
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The exact mechanism that triggers the colorful auroras that dance across the night sky near the Earth’s two poles has been revealed by a quintet of NASA satellites. Scientists already knew that disturbances in the Earth’s magnetic field, called “substorms,” bring charged particles into the Earth’s upper atmosphere, where they collide with gas particles. Those gas particles then release energy as light, which flickers across the sky in waves of greens, reds, and blues.
Now, researchers with NASA’s THEMIS mission say they’ve discovered what sets off those magnetic disturbances. The substorms begin far out in space, roughly a third of the way to the Moon, where magnetic fields from the Earth are thrown together and reconnect to sling charged particles back toward the planet, they say [New Scientist].
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Last January, NASA‘s Messenger probe swooped past Mercury, dipping down to within 125 miles of its surface to take pictures and scientific measurements of the solar system‘s smallest and hottest planet. Now the results have been analyzed, and researchers say the little planet is full of surprises.
Among other revelations, researchers realized that Mercury has a molten iron core that accounts for its strong magnetic field, but that its core is cooling, which explains the fact that the planet has shrunk more than a mile in diameter. Mission scientist Sean Solomon explains: Because solid iron is denser than the liquid form, “as you grow the inner core, the whole volume of the core shrinks,” he says, causing the planet itself to contract [Scientific American]. Messenger’s pictures reveal steep cliffs called “scarps” that researchers believe were pushed upward by the planet’s contraction.
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