In particular, the eleven-year sun-spot cycle discovered in 1840 by Schwabe was found to be important: the rings of trees all around the world are wider when the number of sun-spots increases.

The classical eleven-year cycle is not the only one.

So many cranks have tried to correlate events with the eleven-year cycle - which isn't always eleven years anyway!

I know that the krakens are breeding this year," Kit said, "breaking their usual eleven-year cycle.

Osama bin Laden seems to have based his life on eleven-year cycles," Deming said.

The major fluctuation is the eleven-year solar cycle (sunspot cycle), which causes a periodic variation of about 0.1%.

"Yeah," Dak said, "but it varies on an eleven-year cycle, and we're not at the peak."

Answers to the following questions are being sought: Why does the magnetic field change with an eleven-year cycle?

Carrington's original intent had been to continue the observations through a complete eleven-year solar cycle.

You know how sunspots run on an eleven-year cycle?