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| image: SOON Telescope, Holloman AFB, NOAA |
Solar flares are unimaginably massive bursts of white-hot electrically charged gas fired at us by the sun thousands of times a year. And the biggest ever recorded have been hurled at our planet just recently.
"The sun itself is a thermonuclear furnace," Andrew Coates told PBS's NOVA, "and this flings off huge amounts of dangerous material in very large explosions. In some cases it's about the same mass as Mount Everest actually coming towards us."
As shown on NOVA, two thousand miles beneath our feet, the Earth's molten core generates an invisible magnetic field that protects us from these space storms, as well as other space weather and radiation from space. But scientists are now saying that shield is getting weaker. "The rate of change is higher over the last three hundred years than it has been for any time in the past five thousand," said John Shaw, a geologist at the University of Liverpool. "It's going from a strong field down to a weak field, and it's doing it very quickly."
Scientists think this shift means the magnetic field is getting ready to reverse direction. "That the Earth's magnetic field reverses is an extraordinary phenomenon, but this reversal process is quite common," said Mike Fuller, a geologist at the University of Hawaii. "The last reversal was what, 780,000 years ago?" Scientists have found that these reversals happen, on average, once every 200,000 years. "So in a sense, we are a bit overdue for a reversal," says Fuller. When the magnetic field reverses, compasses will point south instead of north, and animals that use internal compasses for navigation—like some birds, whales, and sea turtles—will have some adjusting to do.
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