How Does the Sun Affect Space Weather?

Our sun is a giant sphere of unimaginably hot hydrogen and helium located around 93 million miles from Earth. Not only does it hold the entire solar system together with its gravity and provide the energy for life to exist on Earth, it also generates space weather.

Space weather is the term used to describe the dynamic conditions and phenomena that occur in the environment between the sun, Earth and beyond. Space weather originates from solar activity and can manifest in various ways.

Sometimes, space weather can have an impact on our planet, interfering with life and technological infrastructure, in space and on the ground.

What Is the Solar Wind?

The sun's outer atmosphere, or corona, constantly spews out a stream of energized, charged particles that reaches speeds of around 1 million miles per hour, known as the solar wind. This stream, which carries with it the solar magnetic field, expands throughout the entire solar system reaching far beyond the orbit of Pluto before it meets the interstellar medium.

A solar flare occurring on the sun
Stock image: Artist's illustration of a solar flare occurring on the sun. These giant magnetic eruptions can cause radio blackouts on Earth. iStock

The solar wind and magnetic field (otherwise known as the interplanetary magnetic field) inflate a "bubble" in the surrounding interstellar material, which is known as the "heliosphere." This region represents the extent of our star's influence.

Variations in the solar wind, such as when it is accelerated to particularly high speeds, can produce changes in the Earth's magnetic field, or magnetosphere, triggering geomagnetic storms that can last hours or even days.

What Is a Solar Flare and a Coronal Mass Ejection?

In addition to the solar wind, which is continuously being produced, certain active events occur on the sun that spew out particularly large quantities of material at even higher speeds and temperatures than normal. These events include solar flares and coronal mass ejections, or CMEs.

CMEs involve the expulsion of billions of tons of charged particles, or plasma, with embedded interplanetary magnetic field from the corona at speeds of up to around 6.7 million miles per hour. The strongest geomagnetic storms on Earth tend to be the result of coronal mass ejections.

While the Earth's magnetic field largely protects us from charged particles emitted by the sun, deflecting most of the energy around our planet, if the ejection of material from the star is strong enough it can sometimes permeate the magnetosphere, sparking a variety of phenomena.

Solar flares are giant magnetic eruptions that occur in a localized region of the sun's atmosphere.

These events, which arise near dark regions on the solar surface called sunspots, spew out electromagnetic radiation, such as X-rays, visible light and ultraviolet light. They can trigger radio blackouts on Earth and solar radiation storms. While CMEs are often associated with solar fares, they can occur independently.

Does the Sun Go Through Cycles?

Solar activity is defined by an 11-year cycle, marked by periods of high and low activity known as solar maximums and minimums.

"Every 11 years, the sun becomes extremely active—that is called a solar maximum," Piyush Mehta, an assistant professor of mechanical and aerospace engineering at West Virginia University, told Newsweek. "Then it goes through what we call a solar minimum—when the sun is very quiet."

A major solar eruption
A major solar eruption in progress on October 29, 2003, in this image captured by the European Space Agency's Solar and Heliospheric Observatory. This eruption produced a large coronal mass ejection.

"The strongest solar storms are likely to occur during solar maximum conditions," he said. "While there can be storms even during solar minimum conditions, the strongest ones are likely to occur when the sun is very active. We are just coming out of a solar minimum, so the sun is starting to get active—it is on its way up. That's generally a good indicator that things are about to start happening."

During solar maximums, the number of sunspots increases and the effects of space weather on the near-Earth environment tend to be greater.

Sunspots, which are sometimes larger than the Earth itself, are dark regions that arise temporarily on the solar surface. While they are cooler than the surrounding areas, they contain particularly strong magnetic fields. Most solar flares and CMEs are associated with these regions.