Explosive ripples suggest the Sun has "seasons"

It's not just Earth weather that's erratic. Our own star, the Sun, also goes through changes.

It's known to go through an 11-year cycle, becoming more or less active. At its peak it explosively fires charged particles out into space, creating powerful sun storms that in turn trigger spectacular auroras on Earth.

Now it seems it has a second, shorter cycle, which lasts about 330 days. In other words, the Sun has a seasonal cycle that lasts almost one Earth year.

Earlier studies had suggested this. Researchers have confirmed it using records of solar activity spanning several decades.

The Sun is an enormous ball of extremely hot gas, which carries an electric charge. The gas is being churned around at very high speeds, and the Sun itself is in constant motion. This means the Sun is magnetic.

"If you move a charge you create a magnetic field. That's what's happening inside the Sun," says Louise Harra of University College London in the UK, who was not involved with the present study.

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