Sunspot activity and its effect on Earth
The following is from Space.com
Sunspots are temporary patches on the surface of the sun that are caused by intense magnetic activity. These structures sometimes erupt into energetic solar storms that send streams of charged particles into space.
Since powerful charged particles from solar storms can occasionally wreak havoc on Earth’s magnetic field by knocking out power grids or disrupting satellites in orbit, a calmer solar cycle could have its advantages.
Astronomers study mysterious sunspots because their number and frequency act as indicators of the sun’s activity, which ebbs and flows in an 11-year cycle. Typically, a cycle takes roughly 5.5 years to move from a solar minimum, when there are few sunspots, to the solar maximum, during which sunspot activity is amplified.
Currently, the sun is in the midst of the period designated as Cycle 24 and is ramping up toward the cycle’s period of maximum activity. However, the recent findings indicate that the activity in the next 11-year solar cycle, Cycle 25, could be greatly reduced. In fact, some scientists are questioning whether this drop in activity could lead to a second Maunder Minimum, which was a 70-year period from 1645 to 1715 when the sun showed virtually no sunspots. [Video: Rivers of Fire Inflame Sunspots]
Hill is the lead author of one of the studies that used data from the Global Oscillation Network Group to look at characteristics of the solar interior. (The group includes six observing stations around the world.) The astronomers examined an east-west zonal wind flow inside the sun, called torsional oscillation. The latitude of this jet stream matches the new sunspot formation in each cycle, and models successfully predicted the late onset of the current Cycle 24.
“We expected to see the start of the zonal flow for Cycle 25 by now, but we see no sign of it,” Hill said. “The flow for Cycle 25 should have appeared in 2008 or 2009. This leads us to believe that the next cycle will be very much delayed, with a minimum longer than the one we just went through.”
Hill estimated that the start of Cycle 25 could be delayed to 2021 or 2022 and will be very weak, if it even happens at all.