Sun's 'quiet period' explained
ASTANA. August 14. KAZINFORM Solar physicists may have discovered why the Sun recently experienced a prolonged period of weak activity, Kazinform refers to BBC.
The most recent so-called "solar minimum" occurred in December 2008.
Its drawn-out nature extended the total length of the last solar cycle - the repeating cycle of the Sun's activity - to 12.6 years, making it the longest in almost 200 years.
During a solar minimum the Sun is less active, producing fewer sunspots and flares.
The new research suggests that the longer-than-expected period of weak activity may have been linked to changes in the way a hot soup of charged particles called plasma circulated in the Sun.
The study, conducted by Dr Mausumi Dikpati of the National Center for Atmospheric Research in Colorado and her US colleagues, is published in the journal Geophysical Research Letters.
The Sun's activity strengthens and weakens on a cycle that typically lasts 10.7 years. Since accurate records began in 1755, there have been 24 such solar cycles.
The 23rd cycle, which ended in December 2008, was both longer than average and had the smallest number of sunspots for a century. Sunspots are areas of intense magnetic activity that are visible as dark spots on the star's surface, Kazinform cites BBC. See www.bbc.co.uk for full version.