WASHINGTON — The sun is heading into an unusual and extended hibernation, scientists predict. Around 2020, sunspots may disappear for years, maybe decades.

But scientists say it is nothing to worry about. Solar storm activity has little to do with life-giving light and warmth from the sun. The effects from a calmer sun are mostly good. There’d be fewer disruptions of satellites and power systems. And it might mean a little less increase in global warming.

It’s happened before, but not for a couple centuries.

“The solar cycle is maybe going into hiatus, sort of like a summertime TV show,” said the National Solar Observatory’s Frank Hill, lead author of a presentation at a solar physics conference in New Mexico.

Scientists don’t know why the sun is going quiet. But all the signs are there.

Hill and colleagues based their prediction on three changes in the sun spotted by scientific teams: Weakening sunspots, fewer streams spewing from the poles of the sun’s corona and a disappearing solar jet stream.

Those three cues show “there’s a good possibility that the sun could be going into some sort of state from which it takes a long time to recover,” said Richard Altrock, an astrophysicist at the Air Force Research Laboratory and study co-author.

The prediction is specifically aimed at the solar cycle starting in 2020. Experts say the sun has already been unusually quiet for about four years with few sunspots – higher magnetic areas that appear as dark spots.

The enormous magnetic field of the sun dictates the solar cycle, which includes sunspots, solar wind and ejection of fast-moving particles that sometimes hit Earth. Every 22 years, the sun’s magnetic field switches north and south, creating an 11-year sunspot cycle. At peak times, like 2001, there are sunspots every day and more frequent solar flares and storms that could disrupt satellites.

Earlier this month, David Hathaway, NASA’s top solar storm scientist, predicted that the current cycle, which started around 2009, will be the weakest in a century.