A geomagnetic storm lit up the night sky over parts of the US during the first weekend of October. South Africa’s national space agency (Sansa) told reporters that the storm originated from a solar flare “that erupted from sunspot 3842 on October 3”. It said it 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 in the African region that lasted 20 Lasted for minutes.”
What is geomagnetic storm? The Conversation Africa asked Sansa’s Amore Nel, who researches geomagnetics, for clarification.
What are geomagnetic storms and how common are they?
Geomagnetic storms are disturbances in the Earth’s magnetic field caused by solar activity. There is a reaction called nuclear fusion that occurs continuously within the Sun’s core. This generates huge amounts of energy. Some of the energy is released in the form of light (sunlight), some in the form of radiation (solar flare), and some in the form of charged particles.
The Sun also continuously emits a stream of charged particles called the solar wind. Occasionally, the Sun releases large bursts of energy, called coronal mass ejections. It sends clouds of these charged particles or plasma into space. I like to explain it to kids this way: The Sun sometimes drinks a soda too fast and then burps. This “burp” is a cloud of plasma that then travels into space. These emissions do not always affect us. But when they do, they collide with Earth’s magnetic field, disrupting it and causing geomagnetic storms.
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 (radiations) and coronal mass ejections. X-flares are radiation; They travel at almost the speed of light and reach Earth within a few minutes. This is the reason for the brief communication disruption that Sansa mentioned on 3 October. But coronal mass ejections take much longer to reach us. We anticipated it would do this last weekend but it actually reached us on the morning of October 8th.
Geomagnetic storms occur frequently. Smaller events occur several times per year. The severity of a storm depends on how intense the solar event that caused it was. Larger, more intense hurricanes are less common but may occur every few years. Solar events are closely linked to the Sun’s 11-year solar cycle, which consists of 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 approaching the peak of Solar Cycle 25, which will occur in July 2025. Solar maxima usually last between two and three years.
Are these storms dangerous? What harm can they do?
Geomagnetic storms are generally not directly harmful to humans, but they can pose risks to modern technology and infrastructure. One of the most notable threats is to the power grid. Powerful storms can generate electrical currents in power lines, potentially overloading transformers and causing blackouts, as happened in Quebec, Canada in 1989.
Satellites in space are also vulnerable. A severe storm can damage onboard electronics, disrupt communications signals and even shorten the lifespan of satellites.
In aviation, geomagnetic storms can disrupt radio communications 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 in danger – excess radiation can be dangerous to equipment and human health.
Is there any benefit to this incident?
Auroras are a surprising aspect of geomagnetic storms. These colorful displays in the night sky occur when charged particles from the Sun are captured in Earth’s magnetic field lines and flow down toward the poles. Here they interact with Earth’s atmosphere, releasing energy that creates the twinkling lights.
Aurora can be seen over both the North and South Pole, aptly named the Northern and Southern Lights. If storms are large enough, it is possible to see them in areas far away from the poles. This happened on 11 May 2024 in South Africa.
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 storms reduce risks?
Geomagnetic storms are monitored using various instruments on Earth and in space. On Earth, magnetometers measure changes in the magnetic field, helping scientists detect disturbances when they occur. For this reason, SANSA Africa operates a dense network of Global Navigation Satellite System receivers and magnetometer stations in various parts of Southern Africa. The agency is also currently setting up a magnetometer station in Ethiopia. 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 forecast models used in space weather stations around the world.
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 prepare for the storm.
For example, power companies may temporarily shut down or reconfigure parts of the grid to avoid overloading during a storm. Satellite operators can put their spacecraft into safe operating modes, such as turning off electronic components, and airlines can reroute flights away from high-risk areas.
Monitoring alone cannot prevent all damage caused by geomagnetic storms. But it can reduce the risks to a great extent. Thanks to early warning systems, we can protect critical infrastructure and reduce the impact of these storms on our daily lives.
,Author: Amore Elsje Nel, Applied Geomagnetic Researcher, South African National Space Agency)
,disclosure statement: Amore Elsje Nel works for the South African National Space Agency. He receives Thuthuka grant (TTK210406592410) from the National Research Foundation.
This article is republished from The Conversation under a Creative Commons license. Read the original article.
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