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Planetary line-up excites the sun

sun and jupiter

Astronomers may have identified the link between sunspot activity and the Jovian planets(Source: NASA/ESA)


In a paper published in the Publications of the Astronomical Society of Australia, astronomer Dr Ian Wilson and colleagues from the University of Southern Queensland, suggest Jupiter and Saturn affect the sun's movement and its rotation, and hence its sunspot activity.

Every 11 years the sun undergoes a period of intense solar activity, marked by flares, coronal mass ejections and sunspots. This period is known as the solar maximum and occurs twice each solar, or Hale, cycle.

"The sun can be thought of as a large bar magnet," says Wilson.

"The equatorial region of the sun spins more rapidly than the poles, and this differential rotation winds up the magnetic field lines like a rubber band."

Wilson says sunspots typically appear wherever these magnetic field lines bubble to the surface.

"Once the peak in sunspot activity is reached, a huge amount of energy is released, the magnetic poles are reversed and a new cycle begins," he says.

Unknown connection

For many years scientists have recognised an apparent connection between the strength of sunspot activity and the movement of the sun in relation to solar system's barycentre, which is driven by the combined gravitational forces of Jupiter and Saturn.

But no one has been able to explain the connection.









But Wilson is cautious.

"It is one thing to show an association and quite another to show cause and effect. We have to be very careful, but we will know in a few years," he says.
