One half of a 22-year cycle on the Sun is about to come to a close that will see the star’s magnetic north and south poles flip their positions. The event is imminent, according to solar physicists from NASA, and could have effects that reach billions of kilometres beyond the orbit of Pluto.
Despite its outwardly unflappable appearance, the plasma inside the Sun responsible for its magnetic field is constantly churning. Every 11 years, it reorganises itself in a little-understood clockwork mechanism, in the process inverting the star’s magnetic polarity.
An important part of this mechanism is thought to be a difference in the rates at which material flows from the equator to the poles and back on the Sun’s surface, as well as the fact that the Sun rotates faster at its poles than at the equator.
“As the polarity moves toward the pole, it erodes the existing opposite polarity,” said Todd Hoeksema, director of the Wilcox Solar Observatory at Stanford University, in a press release. Like a tide, “each little wave brings little more water in, and eventually you get to the full reversal”.
In this period, sunspot activity on the Sun intensifies. There are also more violent ejections of charged particles from its surface as solar flares and coronal mass ejections. These bursts can interact with Earth’s own magnetic field, prompting a surge in the occurrence of auroras, also known as Northern Lights.
Moreover, larger flares “can disturb the ionosphere and disrupt radio communication, damage electronics onboard satellites, cause hazards to airlines flights in polar routes, and even electrical blackouts in regions near the Earth's magnetic poles,” said Prof. Arnab Rai Choudhuri, a theoretical astrophysicist from the Indian Institute of Science, in an interview to The Hindu in August.
Similarly, one beneficial effect is stronger protection against galactic cosmic rays, an influx of energetic particles originating from outside the Solar System which are also known to cause damage to satellites and astronauts orbiting Earth.