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The sun's tumult waxes and wanes in a fairly predictable cycle, with sunspots, patches of intense magnetic activity on the solar surface, peaking in number every 11 or so years. We currently find ourselves in a solar minimum, a period of reduced solar activity, and a deep one at that. Last year was the second-quietest sunspot year of the past century, as the sun was blank on 72.7 percent of the days.
But this year is on pace to be even quieter—through the first three months of 2009 the sun was blank on 86.7 percent of the days. The continued lull in solar activity is mostly good, as the sun can wreak havoc on satellites and infrastructure during its more rambunctious stretches, as we've chronicled in the past.
In the grand scheme of things, though, the sun has probably endured much calmer stretches in its billions of years of existence. In fact, according to NASA, deep solar minima were common until relatively recently—this quiet period will have to persist another year to match the doldrums of 1901 and 1913. The difference this time is that space agencies have a slew of solar-observing satellites ready to observe the sun in a deep slumber. By the time the next solar minimum rolls around in a decade or so, there could be a new member of that fleet: NASA and the European Space Agency's Solar Orbiter spacecraft, which would observe the sun from an orbit about one-fourth the distance separating Earth from the sun, may launch as early as 2015.
Photo of today's quiet sun courtesy of SOHO, NASA/ESA
