A recent solar eruption from sunspot AR3835, coinciding with Earth’s autumnal equinox, has increased the chances of a geomagnetic storm impacting Earth on September 25. While most of the solar plasma is expected to miss Earth, the timing of this event enhances the likelihood of disruptions to communication systems and power grids in high-latitude regions. Skywatchers may also be treated to auroras as the storm interacts with Earth’s magnetosphere.
Solar Eruption During Equinox Raises Potential for Geomagnetic Storm This Week
By Lydia Amazouz
Published on September 23, 2024 19:53
A potential geomagnetic storm is expected to impact Earth on Wednesday, September 25, following a large eruption from sunspot AR3835. This eruption, known as a coronal mass ejection (CME), occurred unexpectedly on Sunday, September 22.
Although most of the solar plasma ejected by this event is forecast to miss Earth, a glancing blow remains possible. The timing of the eruption is critical, as it coincides with Earth's autumnal equinox—a period when geomagnetic storms are more likely to occur due to specific alignments between Earth's and the sun’s magnetic fields.
Unexpected Solar Activity from Sunspot AR3835
Sunspot AR3835 had appeared stable prior to its eruption, leading to little expectation of any solar outbursts from this region of the sun. However, at 5:39 p.m. EDT on Sunday, September 22, the sunspot unleashed an M-class solar flare, sending a wave of solar plasma hurtling toward Earth at an astonishing speed of over 650,000 miles per hour (around 1 million kilometers per hour). Such eruptions, classified as coronal mass ejections, are capable of discharging billions of tons of solar material into space, which can disrupt Earth's magnetosphere if they come into direct contact.
While the bulk of this plasma is expected to miss Earth, NASA's models predict that some of it could still strike a glancing blow on the planet's magnetic field. Under normal conditions, this slight interaction would not be enough to trigger a significant geomagnetic storm. However, the current period around the equinox, when Earth’s magnetic orientation aligns more closely with the sun's, increases the chances of this event having a notable impact.
Happy #SunDay! This week’s space weather report includes:
· 13 M-class flares
· 1 X-class flare
· 27 coronal mass ejections
· 2 geomagnetic stormsThis video from NASA’s Solar Dynamics Observatory shows the week’s activity.
More about flares: https://t.co/SrEf4df5Ws pic.twitter.com/xEkhzrxD0i— NASA Sun & Space (@NASASun) September 22, 2024
How Equinoxes Boost the Risk of Geomagnetic Storms
Equinoxes occur twice a year when Earth’s rotational axis aligns with its orbit around the sun, causing both hemispheres to experience roughly equal amounts of daylight and darkness. This unique alignment also affects the connection between Earth’s magnetic field and the solar wind, the stream of charged particles constantly emitted by the sun. During equinoxes, Earth's magnetic field aligns in such a way that it allows more solar wind to flow directly into the planet's magnetosphere. This reduces the deflection of solar particles, making Earth more susceptible to the effects of coronal mass ejections.
This increased vulnerability to geomagnetic storms during equinoxes is known as the Russell-McPherron effect, named after the scientists who first described the phenomenon in 1973. Their research demonstrated that the seasonal variation in geomagnetic storms could be explained by the way Earth's magnetic field interacts with the sun’s during the equinoxes. Historical data collected between 1932 and 2014 shows that geomagnetic storms are nearly twice as likely to occur around the equinoxes compared to other times of the year, particularly the solstices when Earth's magnetic alignment provides more protection.
Possible Impacts of The Expected Geomagnetic Storm
Geomagnetic storms are disturbances in Earth’s magnetic field that occur when solar plasma, such as that released by a CME, interacts with the magnetosphere. These storms are classified on a scale ranging from G1 (minor) to G5 (extreme) by the NOAA Space Weather Prediction Center. While severe storms at the G5 level can cause widespread power outages, disrupt satellite communications, and damage infrastructure, smaller storms like the one expected on September 25 are much less intense.
The current forecast suggests a G1 or G2 storm, which could lead to minor impacts in areas located at high latitudes. This includes possible disruptions to radio communications and fluctuations in power grids, particularly in regions where these systems are vulnerable. Satellites and spacecraft might also experience minor operational issues, but these are expected to be manageable.
One of the more visible effects of geomagnetic storms is the appearance of auroras—bright displays of light in the night sky, often referred to as the Northern or Southern Lights. These phenomena occur when charged particles from the sun interact with Earth’s atmosphere, creating stunning visual effects that can be seen near the poles. The upcoming storm may provide a good opportunity for skywatchers in high-latitude regions to observe auroras, especially in places like Canada, Alaska, and northern parts of Europe.
Why Monitoring Geomagnetic Activity Matters
Though the geomagnetic storm expected on September 25 is predicted to be mild, it serves as a reminder of the ongoing need to monitor solar activity. As the sun progresses through its 11-year solar cycle, it is entering a more active phase, meaning that larger and more frequent solar flares and CMEs could occur. These solar events can have significant consequences for Earth, especially in terms of technological infrastructure. For example, in March 1989, a powerful geomagnetic storm caused a major blackout in Quebec, Canada, leaving millions without power for several hours.
Scientists, including those at NASA and NOAA, continuously track solar activity to predict and mitigate the effects of geomagnetic storms. By studying past events and current solar conditions, researchers aim to better understand the triggers of these storms and develop strategies to protect critical systems. Improved forecasting tools allow power grid operators, satellite manufacturers, and airlines to take precautionary measures in the face of impending storms, reducing the risk of catastrophic failures.
Looking Forward
While this week's geomagnetic storm is expected to be relatively minor, it highlights the importance of equinox periods in amplifying the effects of solar activity on Earth. As we move further into the sun's active phase, more significant storms may arise, potentially increasing risks to global infrastructure. Continuous monitoring and preparedness remain essential to mitigating the potential impacts of future solar events.
For those living in high-latitude areas, this storm also brings a silver lining—the possibility of witnessing the natural beauty of auroras. As Earth braces for this solar interaction, skywatchers may have a unique opportunity to see the northern or southern lights, a reminder of the powerful and dynamic relationship between our planet and the sun.