Health & Science

Why the sky dances with light; Catching up to the boys; Drinking to the beat; Why day care makes kids fat

Why the sky dances with light

For decades, scientists have debated the cause of the Northern Lights, or aurora borealis—the dance of colored light in the evening sky sometimes seen in the northern latitudes. Now, using data from five NASA satellites and 20 ground observatories, says The Washington Post, a group of scientists has tracked the lights to their source—an explosion of magnetic energy 80,000 miles from Earth. Scientists had long known that the Northern Lights are related to an interaction of the Earth’s magnetic field and the solar wind, a stream of electrically charged particles streaming out from the sun. But they didn’t really understand how that process worked. New observations have revealed that as Earth’s magnetic field extends into space, it meets the solar wind about one-third of the distance to the moon, and is stretched into thin lines like a rubber band. Periodically, the solar energy surges and hurls the magnetic lines back toward Earth, as if it were snapping the rubber band, and the lines reconnect—exploding into a spectacular release of energy and heat. When that energy hits the atmosphere, it become visible as undulating waves of colored light. “Finally, we have the right instruments in the right place at the right time,” says Nicola Fox, a Johns Hopkins University scientist. “It’s allowed scientists to be able to make the necessary observations to settle this heated debate once and for all.”

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