Early in 2001, NASA websites announced that the North-South magnetic field of the Sun was reversing its polarity, was flipping over, as it does every eleven years. This rhythm makes up the well-known 22-year cycle. Solar satellites recorded the event as it happened, making this the first time ever that the event was followed in real time. There are four stages in this cycle, just like there are in a heartbeat, and let's go over them. The North-South magnetic field emerges from its poles, reaching out above and below the ecliptic. As the solar equator is tilted merely six degrees to the ecliptic, this field is more or less perpendicular to it. It grows strongest as the sunspots are at their minimum (the sunspots are then small, and there are only a few around the solar equator) and then grows weak as the sunspot maximum approaches - when, dramatically, it flips right over, between North and South, then starts increasing again with polarity reversed. Then as we saw, around the solar equator, the magnetic field becomes stretched-out and stressed at sunspot maximum, with strands threading in and out of the sunspots. Astronomers talk of a solar 'dynamo' as having a 'self-reversing magnetic field' and this is something unearthly - no magnetic field self-reverses here on Earth.
We are used to thinking of the 11-year sunspot cycle, but let's try instead to visualise two 22-year cycles, proceeding out of phase at the poles and equator. Thus the full solar heartbeat is a four-stage process, as might remind us of the human heartbeat. Between arteries and veins this goes through its four-stage systole-diastole process. Thus the emerging modern picture endorses Galileo's view of the Sun, that:
"...It is rather like the heart of an animal, in which
there is a continual regeneration of the vital spirits,
which sustain and give life to all its members." (2)