By Sid Perkins
WASHINGTON — For the first time, scientists can accurately assess the size, shape and speed of massive flares as they leave the sun, allowing better estimates of when the flares might strike Earth and cause widespread electronic disruptions.
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Since early 2007, NASA researchers have been gathering solar data using sensors onboard two craft known as STEREO, the Solar Terrestrial Relations Observatory (SN: 2/10/07, p. 93). One of those golf-cart-sized, 620-kilogram probes now orbits the sun about 50 million miles ahead of Earth, and the other orbits about 50 million miles behind the planet. The broad span between the two craft, like the separation between human eyeballs, only now provides scientists with two sidelong views of the most massive flares, or coronal mass ejections. The resulting three-dimensional depth perception helps to track the flare as it speeds through space.
Previously, data from STEREO enabled scientists to track a coronal mass ejection from the sun to Earth (SN: 3/3/07, p. 133). Now, the distance between the craft has broadened, allowing researchers to also accurately assess the 3-D structure of flares as they develop on their way to Earth, says Angelos Vourlidas, a project scientist at the Naval Research Laboratory in Washington, D.C who works on the STEREO mission. “We can actually see the shape of the material” as it speeds through space, he said at a news conference April 14 at NASA headquarters.