Sun is heading into a period known as solar minimum, during which activity at the surface will ‘change form,’ as reported by a news agency. In this time, certain types of activity, such as sunspots and solar flares will drop — but, it’s also expected to bring the development of long-lived phenomena including coronal holes.
According to Nasa, solar minimum could also enhance the effects of space weather, potentially disrupting communications and navigation systems, and even causing space junk to ‘hang around.’
The sun follows roughly an 11-year cycle. While sunspots were relatively high back in 2014, they’re now heading toward a low point expected in 2019-2020, according to Nasa.
“This is called solar minimum,” said Dean Pesnell of Nasa’s Goddard Space Flight Center in Greenbelt, MD. “And it’s a regular part of the sunspot cycle,” he added.
The change, however, doesn’t mean that activity ceases altogether, the expert explains.Instead, different types of events tend to take hold. For instance, “During solar minimum we can see the development of long-lived coronal holes,” Pesnell says.
“We see these holes throughout the solar cycle, but during solar minimum, they can last for a long time – six months or more,” he further added.These are areas in the sun’s atmosphere where the magnetic field opens up, sending streams of solar particles into space.
When the resulting solar wind hits Earth’s magnetic field, it can cause space weather events including geomagnetic storms, auroras, and disruptions to communications and even satellites.
According to Nasa, it can even effect the space debris floating around Earth. The drag experienced as objects circle Earth helps to keep low-Earth orbit clean, the space agency explains.
This is the result of heating by ultraviolet radiation from the sun. When solar minimum occurs, the upper atmosphere cools down, reducing the drag. And, Nasa explains, this means space junk is more likely to linger. ‘During solar minimum, the sun’s magnetic field weakens and provides less shielding from these cosmic rays,’ Pesnell says. ‘This can pose an increased threat to astronauts travelling through space.
