NASA - National Aeronautics and Space Administration

Today's forecast: Watch out for a strong solar wind today. Could see auroras in the evening. And can't rule out a late-day solar flare, either. Astronauts and satellite operators should stay tuned for updates.

Doesn't sound like your typical weather forecast? It turns out Earth isn't the only place in the solar system that has to deal with weather. Space has stormy weather, too. But weather in space is different than on Earth. Instead of tornadoes and hurricanes, the threats are solar flares and exploding solar matter.

Image to right: A solar flare is one way that the Sun creates changes in space weather. Credit: NASA

Space weather starts with activity on or near the Sun. Like Earth, the Sun is in a constant state of change:

• Sunspots are local areas of strong magnetic field. They appear as dark spots on the surface of the Sun.
  
  
• Solar flares are sudden explosions of energy. They often occur near sunspots or other active areas of the Sun.
  
  
• Coronal mass ejections are also explosions of energy from the Sun. They are larger than solar flares. And they can have a greater impact on objects and planets in their path.
  
  

Image to left: A strong solar wind can lead to auroras like this one. Credit: NASA

Solar flares and coronal mass ejections can quicken the solar wind. The solar wind is a flow of charged particles that spirals away from the Sun through space. This "electric breeze" can be harmful to astronauts. It can also affect satellites and cause power outages on Earth. One positive effect -- a strong solar wind can lead to auroras. These are incredible displays of light in the night sky.

NASA studies and keeps track of space weather phenomena. The Web sites and products listed below are supported by NASA. They are for students and teachers who want to learn more about space weather:

Blackout! (video)
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Space Weather (CD)
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Making Sun-Earth Connections (CD)
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NASA CONNECT™: Dancing in the Night Sky
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NASA CONNECT™: Having a Solar Blast
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Student Observation Network: Tracking a Solar Star
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Sun-Earth Viewer
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The Dynamic Sun (CD)
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Windows to the Universe: Space Weather
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Dan Stillman, Institute for Global Environmental Strategies