Auroras and sunspots flare together

Q: When do auroras occur? —"lbla", Sandy, Utah

Aurora over Antarctica’s South Pole Station, 1979.  Photo courtesy of NOAA.

A: Auroras usually happen one to four days after a solar flare. In fact, the University of Alaska makes routine aurora forecasts, based on such disturbances. Why?

The Sun radiates a wind of electrons and protons into space, much like a child’s Sun drawing. The particles, interact with Earth’s magnetic field, and trickle into the atmosphere usually near the poles. As they hit molecules and atoms of the high, thin air, the particles glow.

When the Sun erupts at spots along its surface, the solar wind strengthens in gust-like fashion. In a couple of days, the gusty particles rain into Earth’s atmosphere and glow as they hit the air with enhanced intensity. The storm forms the shifting patterns of light we call auroras.

Further Surfing:

University of Alaska: Aurora forecasts

University of Alaska: Aurora prediction map

Franck Pettersen, University of Tromsr: Auroras cause

The Exploratorium: Auroras

(Answered May 23, 2003; updated Oct. 22, 2007)

Click for printer version.