The sun is always belching globs of its inner self into space, but every 11 years or so, changes in our star's magnetic field bring on an increase in sunspots, solar flares and events called coronal mass ejections. The result is a barrage of charged particles hurling toward Earth.

The peak in this cycle is called a "solar maximum" or "solar max."

Solar flares, one type of "space weather" associated with solar maximums, release tremendous amounts of energy, equivalent to a million hundred-megaton nuclear explosions, in just moments, scientists say.

Scientists increasingly suspect that solar cycles affect more than just satellites and power grids. An active sun, known to heat the Earth's outer atmosphere, may also alter our climate. Scientists say a small ice age from 1645 to 1715 corresponded to a time of reduced solar activity, and current rises in temperatures might be related to increased solar activity.

For northern residents, more solar radiation means an increase in the aurora borealis, or northern lights. The solar wind sends charged particles crashing into Earth's atmosphere every day. These particles are attracted to the poles by Earth's magnetosphere, where they excite molecules of nitrogen and oxygen and create the colorful displays of light. The displays should be more pronounced over the next two years.

Daily observations of sunspots began in 1749 at the Zurich Observatory, according to NASA solar physicist David Hathaway. Other observatories began contributing later, and continuous observations began in 1849.

The current 11-year cycle, the 23rd to have been measured by modern scientists, is called Solar Cycle #23.