Unlocking Mysteries in the Sun’s 11-Year Cycle

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Source:  By Nicholas St. Fleur, The New York Times


Excerpt: According to a study published Thursday in the journal Science, our beloved star can be classified as an ordinary “solar-type” star, meaning that the internal processes that control its activity are similar to those seen in many other nearby stars. The sun goes through an 11-year cycle where its magnetic poles flip — imagine the north and south poles on Earth changing place — and during this time the sun’s activity changes between subdued and tumultuous. When activity is low, it is known as solar minimum, and when activity is high, it is known as solar maximum. As the sun nears solar maximum and its activity cycle ramps up, its surface gets covered in sunspots, which are ephemeral dark marks created by strong magnetic activity. “Above sunspots you have complex structures that trigger dynamic phenomenons, eruptions that are like volcanoes,” said Antoine Strugarek, a solar physicist at the French Alternative Energies and Atomic Energy Commission and at the University of Montreal. “Those eruptions can impact our Earth.” ...In a study published Friday in the journal Science Advances, Dr. Morgan found that when the sun is at solar minimum, the quiet corona measures around 1.4 million degrees Celsius. But at solar maximum it jumps to around 1.8 million degrees. Dr. Morgan said he was not sure why the entire corona, including the areas not above a sunspot, heat up as the sun’s activity increases. “The solar corona remains a mystery,” he said. “But we are getting far better at measuring what it’s doing and that’s enabling us to start to understand it.”....

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