1.   An increase in the number of dark spots on the sun Marks such a period of high solar activity.

2.   The ability to forecast ionospheric conditions is related to solar activity.

3.   They say that the concentrated magnetic fields in sunspots spread out all over the sun somewhat after the maximum of solar activity.

4.   The depletion of the ozone layer may be primarily a natural phenomena related to solar activity, according to researchers from NASA and the University of Virginia.

5.   And throughout the fall and winter, expect mind-boggling northern lights, which benefit from a year of high solar activity.

6.   Around the turn of the century, the sun is expected to enter a period of intensified solar activity.

7.   But to varying extents, some have begun rerouting flights in periods of high solar activity, both to reduce potential radiation exposure and to ensure good radio communications.

8.   Fearing cyclical spikes in solar activity, companies hope to use them to preempt pager blackouts.

9.   In May, the airline said, solar activity was normal and was not a factor in choice of routes.