The lack of current solar activity came under the spotlight today at the European Week of Astronomy and Space Science at the University of Hertfordshire.
The Sun has a (roughly) eleven year cycle of activity, but the onset of the latest cycle, 24, has been a painfully prolonged affair, resulting in very few sunspots and flares. Between cycles, activity drops and the Sun's magnetic field reverses itself, producing new sunspots of opposite polarity to those that came before. The first sunspot of cycle 24 was spotted in January 2008 but the cycle has just never got going. What solar physicists describe as the 'onset' - when the new cycle blossoms eradicating all traces of the old cycle - just hasn't happened yet, with cycle 23's prolonged minimum still clinging on in the Sun's southern hemisphere. Comparing the Sun's magnetic flux ratio over several cycles indicates that deviations from the norm began to occur in the southern hemisphere five or six years ago, suggesting that the Sun's decline has a deep-rooted explanation.
The Sun has a (roughly) eleven year cycle of activity, but the onset of the latest cycle, 24, has been a painfully prolonged affair, resulting in very few sunspots and flares. Between cycles, activity drops and the Sun's magnetic field reverses itself, producing new sunspots of opposite polarity to those that came before. The first sunspot of cycle 24 was spotted in January 2008 but the cycle has just never got going. What solar physicists describe as the 'onset' - when the new cycle blossoms eradicating all traces of the old cycle - just hasn't happened yet, with cycle 23's prolonged minimum still clinging on in the Sun's southern hemisphere. Comparing the Sun's magnetic flux ratio over several cycles indicates that deviations from the norm began to occur in the southern hemisphere five or six years ago, suggesting that the Sun's decline has a deep-rooted explanation.
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