The sun is heading into a period known as solar minimum, during which activity at the surface will ‘change form.’

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.’

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The sun is heading into a period known as solar minimum, during which activity at the surface will ‘change form.’ While sunspots were relatively high back in 2014, they’re now heading toward a low point expected in 2019-2020, according to NASA

THE SOLAR CYCLE Conventional wisdom holds that solar activity swings back and forth like a simple pendulum. At one end of the cycle, there is a quiet time with few sunspots and flares. At the other end, solar max brings high sunspot numbers and frequent solar storms. It's a regular rhythm that repeats every 11 years. Reality is more complicated. Astronomers have been counting sunspots for centuries, and they have seen that the solar cycle is not perfectly regular. Advertisement

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.’

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.’

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.

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, 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.

HOW SOLAR WIND IS FORMED The sun and its atmosphere are made of plasma – a mix of positively and negatively charged particles which have separated at extremely high temperatures, that both carries and travels along magnetic field lines. Material from the corona streams out into space, filling the solar system with the solar wind. But scientists found that as the plasma travels further away from the sun, things change. Views of the solar wind from NASA's STEREO spacecraft (left) and after computer processing (right). Scientists used an algorithm to dim the appearance of bright stars and dust in images of the faint solar wind The sun begins to lose magnetic control, forming the boundary that defines the outer corona – the very edge of the sun. The breakup of the rays is similar to the way water shoots out from a squirt gun. First, the water is a smooth and unified stream, but it eventually breaks up into droplets, then smaller drops and eventually a fine, misty spray. A recent Nasa study captured the plasma at the same stage where a stream of water gradually disintegrates into droplets. If charged particles from solar winds hit Earth's magnectic field, this can cause problems for satellite and communication equipment. Advertisement

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.’