Cape Town:

A geomagnetic storm lit up the night sky in parts of the US during the first weekend in October. South Africa’s National Space Agency (Sansa) told reporters that the storm had originated from a solar flare “that erupted from sunspot 3842 on October 3”. It said this was the strongest Earth-facing solar flare recorded by Sansa in the past seven years and that the eruption briefly affected high-frequency radio communications, “resulting in a total radio blackout over the African region which lasted for up to 20 minutes”.

What is a geomagnetic storm? The Conversation Africa asked Sansa’s Amoré Nel, who researches geomagnetics, to explain.

What is a geomagnetic storm and how common are they?

A geomagnetic storm is a disturbance in Earth’s magnetic field caused by solar activity. There’s a reaction called nuclear fusion that occurs continuously deep within the Sun’s core. This generates massive amounts of energy. Some of the energy is released as light (sunlight), some as radiation (solar flares), and some as charged particles.

The Sun also continuously emits a stream of charged particles known as the solar wind. Occasionally, the Sun releases larger bursts of energy, called coronal mass ejections. It sends clouds of these charged particles, or plasma, hurtling through space. I like to explain it to children this way: the Sun sometimes drinks a soda too fast and then burps. This “burp” is the cloud of plasma which then travels through space. These emissions don’t always hit us. But when they do, they collide with Earth’s magnetic field, disrupt it, and lead to a geomagnetic storm.

Earth’s magnetic field is an invisible force that surrounds our planet, acting like a giant magnet with a north and south pole. It helps protect us from harmful solar radiation by deflecting charged particles from the Sun.

The solar flare from 3842 emitted both X-flares (radiation) and a coronal mass ejection. X-flares are radiation; they travel at almost the speed of light and reach Earth within minutes. That’s what caused the brief communications disruption Sansa mentioned on 3 October. But the coronal mass ejection takes much longer to reach us. We’d predicted it would do so over the past weekend but in fact it only reached us on the morning of 8 October.

Geomagnetic storms occur fairly often. Minor ones happen multiple times per year. The severity of a storm depends on how strong the solar event was that caused it. Larger, more intense storms are less common but can happen every few years. Solar events are closely tied to the Sun’s 11-year solar cycle, which has periods of high and low activity. During the peak of the cycle, called solar maximum, more sunspots and solar flares occur, increasing the likelihood of solar storms.

We are now heading towards the peak of Solar Cycle 25, which will be in July 2025. Solar maxima usually last between two and three years.

Are these storms dangerous? What damage can they cause?

Geomagnetic storms are not typically harmful to humans directly, but they can pose risks to modern technology and infrastructure. One of the most notable dangers is to power grids. Powerful storms can induce electric currents in power lines, potentially overloading transformers and causing blackouts, as happened in Quebec, Canada, in 1989.

Satellites in space are also vulnerable. A strong storm can damage electronics onboard, disrupt communication signals, and shorten the lifespan of the satellites themselves.

In aviation, geomagnetic storms can disrupt radio communication and GPS signals, which are vital for aircraft navigation. This is especially important for flights that pass near the polar regions, where the effects of geomagnetic storms are more pronounced. Astronauts and spacecraft are also at risk – the extra radiation can be dangerous for equipment and human health.

Are there any upsides to this phenomenon?

Auroras are a visually stunning aspect of geomagnetic storms. These colourful displays in the night sky occur when charged particles from the Sun get captured in Earth’s magnetic field lines, and funnel down towards the poles. Here they interact with Earth’s atmosphere, releasing energy that produces shimmering lights.

Auroras can be seen at both the north and south pole, aptly named the northern and southern lights. If storms are big enough, it’s possible to see them in regions much further away from the poles. This happened in South Africa on 11 May 2024.

Studying geomagnetic storms provides valuable insights into space weather. By understanding how the Sun’s activity affects Earth, scientists can better predict future storms and work to protect the technologies we rely on. The study of geomagnetic storms also contributes to our understanding of the Sun and space in general.

Can monitoring the storms mitigate the risks?

Geomagnetic storms are monitored using various instruments on Earth and in space. On Earth, magnetometers measure changes in the magnetic field, allowing scientists to track disturbances as they happen. Sansa operates a dense network of Global Navigation Satellite System receivers in Africa, and magnetometer stations in various parts of southern Africa, for this reason. The agency is currently setting up a magnetometer station in Ethiopia, too. This will improve our ability to monitor geomagnetic storms.

In space, satellites equipped with sensors monitor the Sun’s activity and detect solar flares or coronal mass ejections before they reach Earth. This data feeds into prediction models used in space weather centres across the globe.

Once a storm is detected, agencies like Sansa issue alerts and forecasts. These warnings help industries such as power grid operators, satellite companies and aviation authorities to prepare for a storm.

For example, power companies can temporarily shut down or reconfigure parts of the grid to avoid overloading during a storm. Satellite operators can place their spacecraft into safer operating modes, such as switching off electronic components, and airlines can reroute flights away from high-risk areas.

Monitoring alone can’t prevent all the damage caused by geomagnetic storms. But it can greatly reduce the risks. Thanks to early warning systems we can protect crucial infrastructure and minimise the effect these storms have on our daily lives.

(Author: Amoré Elsje Nel, Applied Geomagnetic Researcher, South African National Space Agency)

(Disclosure Statement: Amoré Elsje Nel works for the South African National Space Agency. She receives a Thuthuka Grant (TTK210406592410) from the National Research Foundation)

This article is republished from The Conversation under a Creative Commons license. Read the original article.
 

(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)

The sun as seen by the Solar Orbiter spacecraft in extreme ultraviolet light in this mosaic of 25 individual images taken on March 7, 2023, by the high-resolution telescope of the Extreme Ultraviolet Imager (EUI) instrument. Taken at a wavelength of 17 nanometers, in the extreme ultraviolet region of the electromagnetic spectrum, this image reveals the sun’s upper atmosphere, the corona.
| Photo Credit: Reuters

The solar wind is a ubiquitous feature of our solar system. This relentless high-speed flow of charged particles from the sun fills interplanetary space. On Earth, it triggers geomagnetic storms that can disrupt satellites and it causes the dazzling auroras – the northern and southern lights – at high latitudes.

But precisely how the sun generates the solar wind has remained unclear. New observations by the Solar Orbiter spacecraft may provide an answer.

Researchers on Thursday said the spacecraft has detected numerous relatively small jets of charged particles expelled intermittently from the corona – the sun’s outer atmosphere – at supersonic speeds for 20 to 100 seconds.

The jets emanate from structures on the corona called coronal holes where the sun’s magnetic field stretches into space rather than back into the star. They are called “picoflare jets” due to their relatively small size. They arise from areas a few hundred miles wide – tiny when compared to the immense scale of the sun, which has a diameter of 865,000 miles (1.4 million km).

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“We suggest that these jets could actually be a major source of mass and energy to sustain the solar wind,” said solar physicist Lakshmi Pradeep Chitta of the Max Planck Institute for Solar System Research in Germany, lead author of the research published in the journal Science.

The solar wind consists of plasma – ionized gas, or gas in which the atoms lose their electrons – and is mostly ionized hydrogen.

“Unlike the wind on Earth that circulates the globe, solar wind is ejected outward into interplanetary space,” Chitta said.

“Earth and the other planets in the solar system whiz through the solar wind as they orbit around the sun. Earth’s magnetic field and atmosphere act as shields and protects life by blocking harmful particles and radiation from the sun. But the solar wind continuously propagates outward from the sun and inflates a plasma bubble called the heliosphere that encompasses the planets,” Chitta added.

The heliosphere extends out to about 100 to 120 times further than Earth’s distance to the sun.

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The data for the study was obtained last year by one of the three telescopes on an instrument called the Extreme Ultraviolet Imager aboard the Solar Orbiter, a sun-observing probe built by the European Space Agency and the U.S. space agency NASA that was launched in 2020. The Solar Orbiter was about 31 million miles (50 million km) from the sun at the time – about a third of the distance separating the sun and Earth.

“This finding is important as it sheds more light on the physical mechanism of the solar wind generation,” said solar physicist and study co-author Andrei Zhukov of the Royal Observatory of Belgium.

The solar wind’s existence was predicted by American physicist Eugene Parker in the 1950s and was verified in the 1960s.

“Still, the origin of the solar wind remains a longstanding puzzle in astrophysics,” Chitta said. “A key challenge is to identify the dominant physical process that powers the solar wind.”

The Solar Orbiter is discovering new details about the solar wind and is expected to obtain even better data in the coming years using additional instruments and viewing the sun from other angles.

Zhukov said stellar wind is a phenomenon common to most, if not all, stars, though the physical mechanism may differ among various types of stars.

“Our understanding of the sun is much more detailed than the understanding of other stars, due to its proximity and thus the possibility to make more detailed observations,” Zhukov added.