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].
The results, announced at the American Geophysical Union meeting, were obtained by NASA’s five THEMIS satellites, one of which flew through a band of solar particles as they streamed through a breach in 2007. Sensors recorded a torrent of solar wind particles streaming into the magnetosphere, said Raeder. “The opening was huge — four times wider than Earth itself,” said Raeder. “This kind of influx is an order of magnitude greater than what we thought was possible” [Reuters].
The findings will help scientists prepare for the next batch of intense solar storms. The Sun operates on an 11-year cycle, alternating between active and quiet periods. We are currently in a quiet period, with few sunspots on the sun’s surface and fewer solar flares, though the next cycle of activity has begun. It is expected to peak around 2012, bringing lots of sunspots, flares and coronal mass ejections [SPACE.com]. The magnetic fields of the sun and Earth are expected to be in alignment around the time of the next peak, which could amplify the storms’ effects.
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