Sunspot

A sunspot is a region on the Sun's surface (photosphere) that is marked by a lower temperature than its surroundings, and intense magnetic activity. Although they are blindingly bright, at temperatures of roughly 5000 K, the contrast with the surrounding material at some 6000 K leaves them clearly visible as dark spots. If they were isolated from the surrounding photosphere they would be brighter than an electric arc.

Application

Sunspots are relatively easily observed -- a small telescope with a projection facility suffices. In some circumstances (low sunsets) sunspots can be observed with the naked eye. Note: Never look directly into the Sun; it can cause permanent, incurable damage to the retina before you know that anything is happening.

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Due to their link to other kinds of solar activity, they can be used to predict the space weather and with it the state of the ionosphere. Thus they can help predict conditions of short-wave propagation or satellite communications.

Related Topics:
Space weather - Ionosphere

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