Our sun is a variable star

For some years now, an unorthodox idea has been gaining favor among astronomers.
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 It contradicts old teachings and unsettles thoughtful observers, especially climatologists.
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The sun, explains Lika Guhathakurta of NASA headquarters in Washington DC, is a variable star.
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But it looks so constant.
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That's only a limitation of the human eye.
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Modern telescopes and spacecraft have penetrated the sun's blinding glare and found a maelstrom of unpredictable turmoil.
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Solar flares explode with the power of a billion atomic bombs.
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Clouds of magnetized gas (CMEs) big enough to swallow planets break away from the stellar surface.
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Holes in the sun's atmosphere spew million mile-per-hour gusts of solar wind.
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And those are the things that can happen in just one day.
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Over longer periods of decades to centuries, solar activity waxes and wanes with a complex rhythm that researchers are still sorting out.
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The most famous "beat" is the 11-year sunspot cycle, described in many texts as a regular, clockwork process.
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In fact, it seems to have a mind of its own.
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It's not even 11 years, says Guhathakurtha.
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The cycle ranges in length from 9 to 12 years.
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Some cycles are intense, with many sunspots and solar flares; others are mild, with relatively little solar activity.
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In the 17th century, during a period called the 'Maunder Minimum,' the cycle appeared to stop altogether for about 70 years and no one knows why.
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There is no need to go so far back in time, however, to find an example of the cycle's unpredictability.
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Right now the sun is climbing out of a century-class solar minimum that almost no one anticipated
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Our sun has so much more to teach us
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NASA