Solar activity increases and decreases in cycles or periods of 11 years. Thus, every 11 years, our star king increases his amount of plasma and generates a great storm of energy fields that reach Earth and affect electronic devices.
After studying it for decades through telescopic observation and also with space probes, astronomers may have finally discovered what causes the Sun’s 11-year activity cycle, and involves a “tsunami” of magnetic fields.
The Sun, like other stars, goes through a cycle marked by a change in magnetic activity, radiation levels and the amount and size of sunspots. While the 11-year cycle of our Sun was discovered more than a century ago, predicting exactly when a cycle ends and a new one begins has been an ongoing challenge.
A couple of related studies have traced the activity of the Sun over 140 years, looking for clues about the solar cycle that are visible on the surface.
“New solar cycles always begin with the appearance of a sunspot with inverted polarity and high latitude,” said David Hathaway of NASA’s Marshall Space Flight Center. “Inverted polarity” means that the sunspot in question has a magnetic polarity opposite to that of the sunspots of the previous cycle.
Solar storms can disable the satellites we depend on to forecast the weather or for GPS (Global Positioning System) navigation systems to work, “said Hathaway.
Radio interference from solar flares can directly affect cell phone reception, while coronal mass ejections that hit the Earth can cause power outages. “The most famous example is the blackout that took place in Quebec in 1989, which left some Canadians without power for six days,” he added.
Air traffic can also be affected. “Solar storms have a great effect on the polar regions of our planet,” says Steve Hill of the US Space Weather Forecasting Center.
“When airplanes fly over the poles during solar storms they may experience suspensions in radio transmissions, navigation errors or it may happen that their computers restart, all this caused by space radiation,” he said.
Those bright flashes of ultraviolet light and the Sun’s magnetic fields seem to drive the cycle itself, and monitoring those flashes could help scientists predict when a new one will begin.
“We have observed the sunspot cycle for hundreds of years,” Mausumi Dikpati, a scientist at the National Center for Atmospheric Research (NCAR) and lead author of the tsunami study, published earlier this year in the journal Nature, said in a statement .
“But it has been a mystery which mechanism could carry a signal from the equator, where the cycle ends, to the middle latitudes of the sun, where the next cycle begins, in a relatively short period of time.”
The first study looked for markers at the end of a solar cycle by visualizing the movement of the so-called corona bright spots or flashes of extreme ultraviolet light in the Sun’s corona.
Light flickers first appear at a higher altitude than sunspots and move toward the equator, the researchers found. There, blinks overlap with sunspots at mid latitudes before blinks and sunspots reach the equator and disappear, according to the study.
Its disappearance, which scientists considered the “terminator” event, is followed shortly by a great explosion of activity in the blinking lights.
The second study, published in July in the journal Solar Physics, was based on the findings of the terminator study, suggesting that bright flashes marked the movement of the Sun’s magnetic fields. These magnetic fields wrap around the Sun as bands in east and west, and also move toward the equator near the end of the solar cycle.
Such fields also act as “magnetic dams,” trapping plasma behind them while they travel. Once these fields reach the center, the opposite charges of the magnetic fields that move from the east and the west collide with each other, releasing the accumulated magnetic charge of the fields in a fluid motion. The researchers called this fluid avalanche a “tsunami.”
As the solar plasma tsunami reaches the mid-latitudes of the star, it encounters the incoming magnetic fields of the next solar cycle, and this collision causes the bright light to flash, as the study emphasizes.
The study authors said they plan to use the Parker Solar Probe, the Solar Dynamics Observatory and the Daniel K. Inouye Solar Telescope to observe the current solar cycle. When it ends in the first half of the year 2020 and a new one begins, researchers will be able to test their results.
“We believe that the results could revolutionize our understanding of the solar interior and the processes that create sunspots and shape the sunspot cycle,” said Scott McIntosh, a NCAR scientist and lead author of the “terminator” study.