What does the solar activity cycle have to do with auroral activity?


Usually, times of the greatest solar activity are correlated with auroral activity, but the details are quite complex. When the sun is near its 'sunspot maximum' level, you can generally expect to see almost nightly auroral activity because the density of active regions on the sun is so high that the odds are excellent that one or a few will be in the right location to affect the Earth. There is about a 2- 3 day lag between an event on the sun and effects near the earth because it takes the plasma, traveling at a million miles an hour, several days to get here from the sun. Also, if the active region is not located in just the right part of the sun, the plasma it ejects will not be where the Earth is in its orbit 2- 3 days later and no auroral effects will be seen.

Curiously, although we are at the minimum of the sunspot cycle during 1996-7, we have had a few interesting storms on the sun that ejected particles. One as in January, 1997; the other in April 1997.


Return to the Ask the Space Scientist main page.

All answers are provided by Dr. Sten Odenwald (Raytheon STX) for the
NASA IMAGE/POETRY Education and Public Outreach program.