and the Solar Max

The Solar Wind

Solar Flare During the course of the solar cycle, tremendous explosions occur on the surface of the sun. Called solar flares, these colossal flareups can last from a few minutes to a few hours and can release as much energy as a billion tons of dynamite! Solar flares occur near sunspots, usually along the dividing line between areas of oppositely directed magnetic fields. The largest flares usually occur during the years preceding and following the "solar max".

Solar flares are directly responsible for disruptions of Earthly radio transmissions. As the energy from the solar flares races away from the sun—called the solar wind—some of the high-energy particles are able to penetrate a layer of Earth's atmosphere called the ionosphere (the ionosphere plays a part in radio transmission because it reflects radio waves back down to the surface of the Earth). When the ionosphere is disrupted by the solar wind, static radio reception or even a complete loss of signal can be experienced.

In addition, the solar wind can affect power grids and Earth-orbiting satellites. In 1989, a power blackout in the American northeast and Canada was triggered by a geomagnetic storm that overloaded one part of the power grid and caused a blackout to cascade through the system. Several satellites have been disrupted as high-energy particles associated with the solar wind flowed through sections of the satellites and damaged their sensitive electronics. In 1979, the Skylab space station prematurely re-entered Earth's atmosphere due to a malfunction caused by increased solar activity, and consequently rained debris over the Indian Ocean and parts of western Australia.

For these reasons, operators of satellites, power systems, pipelines, and other sensitive systems keep an eye on solar-terrestrial activities by way of the Space Environment Center in Boulder, Colorado. The center, in turn, collects data from ground and orbiting solar telescopes, magnetometers, and other instruments, and posts warnings on the Internet and through direct contact.


Sunspots and the Solar Max
What exactly is a sunspot?
The Butterfly Diagram
The Solar Wind

top left: A solar flare erupting (252 kb), as seen by the Extreme Ultraviolet Imaging Telescope aboard the Solar and Heliospheric Observatory. (Image and animation courtesy NASA Goddard Space Flight Center)

next: References
back: The Butterfly Diagram