Today, most of us are familiar with the term “space weather.” In fact, “solar weather” is a more accurate term. Because space weather means what the sun is sending in our direction and how it affects our cosmic neighborhood, Earth, and our activities. The main things we have to consider are the solar wind, solar flares, and coronal mass ejections.
The solar wind is a continuous and highly variable burst of particles and magnetic fields that move outward from the Sun at speeds of hundreds to thousands of kilometers per second. Most of it is kept away from the Earth by the Earth’s magnetic field. If you leave it alone, the field should look like a donut.
The solar wind blows around it, forming a long teardrop shape. We can see how important magnetic fields are to us by what we see on Mars. The planet’s magnetic field weakened long ago, and the solar wind has since washed away much of the planet’s atmosphere.
The Sun is a ball of hot plasma powered by nuclear fusion and passed through a magnetic field. These emerge through the Earth’s surface, forming giant loops filled with trapped, multimillion-degree plasma. This “magnetoplasma” is more like an elastic mass.
It can be stretched, twisted, and compressed. The constant movement of the sun’s surface puts tremendous stress on these loops, causing them to store huge amounts of energy. In most cases, there is a process that relieves stress and slowly releases energy. But from time to time, instabilities occur and that energy is released catastrophically, causing massive explosions known as solar flares.
Large bursts of high-energy radiation, such as X-rays, are produced. The electrons are accelerated to nearly the speed of light and launched into space along with a beam of other high-energy particles.
Here on Earth’s surface, protected by our magnetic field and atmosphere, these hazards pose little threat. But for people in space or flying above the high-altitude poles, radiation and high-energy particles from the sun can cause problems.
A coronal mass ejection, or “solar storm,” is a loop that breaks off at its base and shoots into space at thousands of kilometers per second. They are primarily blocked by the Earth’s magnetic field, but they can create powerful magnetic storms that can cause power outages and other problems.
For those of us here on Earth, solar activity throughout history has posed little threat to life as far as we know. The main thing was the spectacular and beautiful aurora borealis that appeared from time to time.
However, things have begun to change in recent decades. As we become more dependent on high-tech infrastructure, we become increasingly vulnerable to disruptions to our high-tech lives.
The big question here is how big the solar flare will be. Could they, rather than our technological infrastructure, threaten our way of life?
Astronomers recently detected a flare that emitted millions of times more energy than the largest solar flare ever observed on another star. The star, designated HD 283572, is located about 400 light-years away. It is a young star, only about 3 million years old, and about 40% more massive than the Sun. If the sun were to cause such an event, it is not clear whether our atmosphere and magnetic field would be able to protect us from the environmental damage it could cause.
Such flares could have devastating effects on life forming on young planets. When searching for life on planets orbiting other stars, it seems necessary to consider the behavior of those stars. Only one of these megaflares has been detected so far, so we don’t know how rare it is.
Ken Tapping is an astronomer at the National Research Council’s Dominion Radio Astrophysical Observatory in Penticton.