The Sun has been strangely unblemished this year. On more than 200 days so far this year, no sunspots were spotted. That makes the Sun blanker this year than in any year since 1954, when it was spotless for 241 days.
The Sun goes through a regular 11-year cycle, and it is now emerging from the quietest part of the cycle, or solar minimum. But even for this phase it has been unusually quiet, with little roiling of the magnetic fields that induce sunspots.
“It’s starting with a murmur,” said David H. Hathaway, a solar physicist at NASA’s Marshall Space Flight Center in Huntsville, Ala.
As of Thursday, the 276th day of the year, the National Oceanic and Atmospheric Administration’s Space Weather Prediction Center in Boulder, Colo., had counted 205 days without a sunspot.
In another sign of solar quiescence, scientists reported last month that the solar wind, a rush of charged particles continually spewed from the Sun at a million miles an hour, had diminished to its lowest level in 50 years.
Scientists are not sure why this minimum has been especially minimal, and the episode is even playing into the global warming debate. Some wonder if this could be the start of an extended period of solar indolence that would more than offset the warming effect of human-made carbon dioxide emissions. From the middle of the 17th century to the early 18th, a period known as the Maunder Minimum, sunspots were extremely rare, and the reduced activity coincided with lower temperatures in what is known as the Little Ice Age. – nytimes