The sun has been surprisingly quiet lately, and until now astronomers couldn’t figure out why. An 11-year cycle governs solar flares and sunspots, and researchers knew that we were at the end of a cycle in a “solar minimum” or quiet period–but that somnolence has continued for an extra year beyond the point at which researchers expected sunspot activity to resume. Comments Australian astronomer Phil Wilkinson: “We have had a drought of sunspots…. This is the longest period the sun has been quiet since the start of the Space Age. Seeing the sun doing nothing is really exciting,” he said, adding it made physicists wonder how little they really understood [Sydney Morning Herald].
Now, new observations announced at a meeting of the American Astronomical Society reveal a possible explanation: “sluggish” solar jet streams 4,350 miles below the surface of the sun. Every 11 years, the sun simultaneously generates twin streams of plasma at each of its poles. Unlike the jet streams on Earth, the solar versions are magnetized and travel only toward the equator. This migration takes place very slowly–at about 10 kilometers per hour. For reasons still not understood, when the streams reach 22 degrees of latitude, north and south, they touch off a new solar cycle, and the sunspots reappear [ScienceNOW Daily News].
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A pair of solar observers known as the STEREO spacecraft have taken the first 3-D pictures of the sun’s powerful storms, during which billions of tons of charged particles erupt from the sun’s surface. The two spacecraft have taken up two positions about 100 million miles apart: Not unlike human eyes, the satellites’ two points of view allow for combination images that render scenes in three dimensions [National Geographic News].
Solar storms can have serious repercussions here on Earth. They can disrupt GPS signals and power grids, damage satellites, and bombard astronauts with solar radiation, experts said [National Geographic News]. But with the STEREO system, researchers say they can predict when a fierce storm will hit Earth 24 hours in advance (an improvement over previous 12-hour predictions). Says researcher Chris Davies: “That’s ample time to power down a satellite until the worst of the storm has passed; and if you’re an astronaut on the space station, you would have had plenty of time to get into an area that has much better shielding” [BBC News]. While STEREO is a temporary scientific research mission, researchers say it provides an example of how a “space weather” early-warning system would work.
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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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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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