Sun has fewest sunspots since 1913, better GPS

The sun has been unusually quiet lately, with fewer sunspots and weaker magnetic fields than in nearly a century. A quiet sun is good for Earth: GPS systems are more accurate, satellites stay in orbit longer; even the effects of manmade global warming are marginally reduced, though just by three-tenths of a degree at most.

It’s all a normal part of the strange but regular cycles of the sun’s activity. Scientists don’t know why it happens, but “for humankind it’s probably a good thing,” said David Hathaway, chief solar physicist at NASA’s Marshall Space Flight Center in Huntsville, Ala.
This lower activity is shrinking our atmosphere a bit, too. Again, not a problem. The sun isn’t bombarding the Earth with the usual amount of short-wave radiation that expands the atmosphere. Researchers at the University of Texas in Dallas found the Earth’s upper atmospheric boundary at the lowest in the history of the space age. It’s about 125 miles lower than normal.

For centuries, people have been counting sunspots, which are cooler, darker areas of intense magnetic fields that form on the sun’s surface. The number of sunspots in recent months has been the lowest since 1913, according to NASA. Scientists are looking as far back as the early 1800s for similar quiet periods. They generally last about five years. This quiet spell, which started in 2007, may follow suit.

AP