Posts Tagged ‘Solar Minimums

New Insights On How Solar Minimums Affect Earth

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The solar minimum occurs approximately every 11 years when fewer sunspots like these appear.

Since 1611, humans have recorded the comings and goings of black spots on the sun. The number of these sunspots wax and wane over approximately an 11-year cycle — more sunspots generally mean more activity and eruptions on the sun and vice versa. The number of sunspots can change from cycle to cycle and 2008 saw the longest and weakest solar minimum since scientists have been monitoring the sun with space-based instruments.
Observations have shown, however, that magnetic effects on Earth due to the sun, effects that cause the aurora to appear, did not go down in synch with the cycle of low magnetism on the sun. Now, a paper in Annales Geophysicae that appeared on May 16, 2011 reports that these effects on Earth did in fact reach a minimum — indeed they attained their lowest levels of the century — but some eight months later. The scientists believe that factors in the speed of the solar wind, and the strength and direction of the magnetic fields embedded within it, helped produce this anomalous low.
“Historically, the solar minimum is defined by sunspot number,” says space weather scientist Bruce Tsurutani at NASA’s Jet Propulsion Lab in Pasadena, Calif., who is first author on the paper. “Based on that, 2008 was identified as the period of solar minimum. But the geomagnetic effects on Earth reached their minimum quite some time later in 2009. So we decided to look at what caused the geomagnetic minimum.”……….
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Read also: Sluggish sun may ‘sit out’ next solar cycle

Written by physicsgg

June 15, 2011 at 9:17 am


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