A powerful solar eruption is expected to hit Earth soon, according to a forecast from the National Oceanic and Atmospheric Administration's Space Weather Prediction Center.
A coronal mass ejection -- a massive burst of solar material and magnetic field from the sun's outer atmosphere -- is expected to arrive at Earth early to midday Tuesday, according to NOAA. The CME, linked to an M8.1 solar flare, could cause elevated geomagnetic activity and potentially a G3 storm, the third level on the Space Weather Scale.
A geomagnetic storm of this magnitude is considered "strong" and has the potential to cause some minor impacts to technology, such as satellite disruptions and radio communication issues.
Solar activity could also cause stronger-than-usual auroras, making the northern lights visible in more U.S. regions than usual, including many northern states and some states from the lower Midwest to Oregon, according to NOAA.
What is space weather?
Weather is commonly thought of as the conditions outside, from rain and snow to sunny skies. But beyond Earth's atmosphere, there's another kind of weather that can be just as impactful.
Space weather is primarily influenced by the sun, which generates energy through nuclear fusion. It refers to the conditions in the space environment and how these conditions impact objects throughout our solar system, including Earth and the thousands of satellites that orbit it, according to NASA.
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The Sun constantly emits high-energy charged particles, plasma eruptions and bursts of radiation that can disrupt the space conditions when they reach Earth. Fortunately, our planet's magnetic field and atmosphere shield us from the most hazardous effects. But it doesn't stop everything.
One of the most well-known interactions of solar wind colliding with Earth's magnetosphere and thin, high atmosphere comes in the form of auroras, which produce the beautiful northern lights.
However, many impacts of solar activity can be harmful, affecting a wide range of technologies from communication systems to GPS to power grids, according to NOAA.
How is space weather monitored and measured?
Both NASA and NOAA monitor space weather. NOAA's Space Weather Prediction Center, however, is specifically focused on monitoring and predicting events in the space environment that can affect technology and life on Earth.
The Space Weather Prediction Center tracks a variety of space weather events, including geomagnetic storms, solar radiation storms, solar flares and sunspots.
The agency uses NOAA Space Weather Scales to communicate current and forecasted space weather conditions for three of the most impactful events: geomagnetic storms, solar radiation storms and radio blackouts -- quantifying their potential effect on people and infrastructure.
To communicate the severity of these events, the NOAA Space Weather Scales use numbered levels (1-5), similar to how earthquakes, hurricanes and tornadoes are measured. Each level outlines the potential impacts, measures the intensity of the phenomenon and estimates how often such events occur.
What are the impacts of geomagnetic storms?
Geomagnetic storms often attract the most attention because of their potential to disrupt communication systems, GPS and power grids.
Significant geomagnetic storms are often caused by a Coronal Mass Ejection from the sun, a massive burst of charged particles embedded in a magnetic field that interacts with Earth's magnetic field, temporarily disturbing it and releasing large amounts of energy, according to NOAA.
Geomagnetic storm intensity is ranked on the G-scale for both current and forecasted conditions, with G1 storms considered "minor" and G5 storms considered "extreme.”
The G-scale measures geomagnetic storms based on the planetary K-index, known as Kp, which ranges from zero to nine. This index is calculated by observing fluctuations in Earth's magnetic field. G1 and G2 level storms are quite common and occur frequently throughout the year. In contrast, G5 storms are extremely rare and have the most significant impacts.
Notable technology disruptions and widespread auroras typically occur when a geomagnetic storm reaches G3 (strong), becoming more significant at G4 (severe). G3 and G4 storms are not rare, with several occurring each year depending on the solar cycle.
The Space Weather Prediction Center will issue geomagnetic storm watches and warnings when the latest forecasts indicate that geomagnetic storms are likely or imminent, providing information on expected intensity, timing and potential impacts. The agency also issues guidance on where an aurora may be visible during an ongoing event.
Notable space weather events
The strongest geomagnetic storm in over two decades arrived in May 2024. The G5 storm brought a remarkable display of the aurora borealis (northern lights), visible from many areas worldwide, including locations where aurora sightings are uncommon, according to NASA.
The incident also caused several issues on the ground, including tripping high-voltage lines, overheating transformers, and GPS-guided tractors veering off course, which disrupted planting plans in the Midwest U.S. Additionally, several trans-Atlantic flights were forced to change course due to concerns about potential communication and navigation failures.
One of the most significant solar activity outbreaks in recent history occurred in late October 2003, when a series of massive solar storms hit Earth. The global effects were wide-ranging, impacting power grids, airline flights and spacecraft operations, according to NOAA. These extreme and prolonged geomagnetic storms, some reaching G5 intensity, brought widespread aurora sightings on Oct. 29 and 30, visible as far south as Texas and Florida.
As recently as early Monday morning, a powerful solar flare, classified as an R3 (strong) radio‑blackout event by NOAA, impacted Australia and parts of Southeast Asia. This intense flare caused a major radio blackout on the sunlit side of Earth. The R3 rating indicates a wide-area loss of high-frequency radio communications, lasting roughly an hour. Events like this can disrupt satellite operations, degrade GPS signals and interfere with radio communications used by aviation, maritime operations, and other critical services.
