If you looked at the National Weather Service website a couple of months ago, you probably saw a few unusual terms mixed in with the usual daily forecast: high-energy protons, impulsive radio blackout, and geomagnetic storm, among others. The forecast warned not of killer tornadoes or heat waves, but of an eruption on the surface of the Sun.
Space weather is the interaction between the Sun and Earth's magnetic field. Most of the time, the weather is calm, and the major effect is the glowing curtains of light known as aurorae.
But sometimes, the Sun produces big storms. They're most common when the Sun is at the peak of its 11-year magnetic cycle. If the storms are aimed at Earth, they can damage orbiting satellites, disrupt air travel, and even trigger blackouts. So the people who operate satellites, airlines, and power grids need to know when the space weather could cause problems.
Forecasters use several satellites to keep an eye on the Sun around the clock. The visible light and other electromagnetic energy from the storms reach Earth in minutes. They precede the most damaging effects of the storms -- electrically charged particles -- by a couple of days.
That lets forecasters see the storm's intensity, and plot how much of its outburst of particles is likely to hit Earth. That allows them to issue forecasts a couple of days before the storms hit -- providing early warning of storms from the Sun.
Script by Damond Benningfield, Copyright 2011
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