Every year there are a number of eclipses (solar and lunar).

Each of these 'individual' eclipses are part of wider families of eclipses.

Over an 18 year cycle (a saros), around 90 such families manifest an eclipse.

The cycle then repeats, each family having its turn in sequence (though over centuries, old families are replaced by new ones).

As the eclipse families succeed one another, their different natures influence events on Earth.