Seasons of the Sun - Solar Cycyle

We are currently in the middle of the 11 year solar cycle, with the Earth experiencing the effects through changes to radio communications, power distribution, orbiting spacecraft and even the weather. So predicting what the Sun will do next is in all our interests.

Most people think of the sun as a featureless, unchanging ball of light. But the Sun actually has seasons, or cycles of activity and relative inactivity. Right now, we are in the middle of the maximum activity phase of the current 11 year solar cycle. The Sun is daily exhibiting many sunspots and flares. We feel the effects of an active Sun here on Earth - radio communications, power distribution, orbiting spacecraft and even the weather are all affected.

Sunspots are relatively cool areas on the Sun that appear as dark blotches. Scientists count the number of sunspots to measure the magnitude of a solar cycle, and to determine how long the cycle lasts. If scientists were able to predict sunspot activity, not only would we know ahead of time what the Sun will do, but we might gain a better understanding of how the Sun operates.

Dr. David Hathaway, along with Robert Wilson and Ed Reichmann, looked at many different ways scientists predict sunspot activity. They tested each statistical method to see which worked best, and then combined the top two methods to develop an even better prediction method of their own.

"There are many different ways of predicting the sunspot cycle," says Hathaway. "but until now there has never been a systemic study to determine whether one method works better than another. After examining various methods, we found that some of the techniques currently used and touted are basically useless."

By looking at more than 15 methods, the scientists found that 8 or 9 were better than average at predicting solar maxima - when the sun is at its most active. The two best methods essentially used the same information - disturbances in the Earth's magnetic field.

"Explosions from the sun travel through space and hit the Earth, causing the magnetic field to wobble and shake," says Hathaway.

Joan Feynman from NASA's Jet Propulsion Laboratory developed one of the top two methods, the Australian astronomer Richard Thompson developed the other. Although each scientist took a different approach to the data and reported different results, they both looked at how the Earth's magnetic field shook during the previous solar cycle to predict the sizeof the next one.