The Solar Cycle

The Sun is a large ball of hot gases.  It has a very strong magnetic field.  You can think of the Sun as having a large bar magnet going straight through its center.  Magnetic field lines are imaginary lines that reach out from the magnet and loop around the Sun.  They start at the north end of the magnet and end at the south end.   This means that they start at the Sun's south pole, and end at its north pole.  These lines make up the Sun's magnetic field.  The picture below illustrates this effect.

Now imagine that this bar magnet rotates within the Sun to create the solar cycle.  Over an 11-year period, the magnet completes half its cycle, flipping so that the north and south ends of the magnet eventually trade places.    During this time, the number of sunspots that appear on the Sun goes from high to low.   The period of high activity and more sunspots is called the solar maximum, while the period of low activity and fewer sunspots is called the solar minimum.  A full solar cycle takes 22 years.

Although there isn't a real magnet going through the center of the Sun, this is the best way to understand how its magnetic field is created.