Geomagnetic storms are rated on a 1-5 scale, with 1 being the weakest and 5 having the most potential for damage. Even a G1 geomagnetic storm could create issues: there could be weak power grid fluctuations and minor impacts on satellite operations. Aurora, also known as the “Northern Lights”, could be visible at high latitudes from northern Michigan and Maine to points north. Impacts and aurora change as the geomagnetic storm scale increase.
While there are fears that a future blast from the sun will disrupt electricity, communication, and internet lines for weeks, this event does not seem to have that type of potential with it. However, some impacts, including an electrified display of the Northern Lights at northern latitudes, are expected.
The Space Weather Prediction Center says the area of impact will focus primarily poleward of 55 degrees Geomagnetic Latitude. In a statement released this afternoon, the SWPC says, “Induced currents / power grid fluctuations can occur. High-latitude power systems may experience voltage alarms. Spacecraft – satellite orientation irregularities may occur; increased drag on low Earth-orbit satellites is possible.” The SWPC also adds, “high frequency radio propagation can fade at higher latitudes.”
A significant solar flare erupted from the sun on October 9, producing an Earth-directed Coronal Mass Ejection (CME) that is due to deliver impacts to Earth sometime late October 11 / early October 12. Due to the impacts of this unfolding M1.6-class solar flare event on Earth, NOAA’s Space Weather Prediction Center (SWPC) has issued a G2 Geomagnetic Storm Watch which begins tomorrow, October 11.
Chart showing NOAA Space Weather Scales for Geomagnetic Storms. Image: NOAA
This map shows how far south the Northern Lights could appear at different KP index levels. While a KP of 3 or less would keep them in northern latitudes of Alaska and Canada, a KP of 9 would make them visible in places like Salt Lake City, St. Louis, Washington, DC, Chicago, Philadelphia, New York, Boston, and Portland. Right now, the SWPC believes the KP value will be around 6 late on the 11th of October. Image: NOAA
The event forecast for October 11 could generate aurora as low as New York to Wisconsin to Washington State. The K-index, and by extension the Planetary K-index, are used to characterize the magnitude of geomagnetic storms. The SWPCS says that Kp is an excellent indicator of disturbances in the Earth’s magnetic field and is used by SWPC to decide whether geomagnetic alerts and warnings need to be issued for users who are affected by these disturbances. Beyond signifying how bad a geomagnetic storm’s impact can be felt, the Kp index can also help indicate how low the aurora will be. In this case, the October 11 storm is forecast to have a Kp value of at least 6.
The Sun is the primary cause of space weather. At times, the Sun can be thought of as going through a “stormy” period where its surface is more active than normal. When this happens, the Sun can send streams of energized particles out in all directions. When these energized particles interact with the outer reaches of our atmosphere, the aurora borealis (the Northern Lights) and the aurora australis (the Southern Lights) can result.
Region 2864, circled here on the sun, could set the stage for more aurora displays on Earth and perhaps a full-fledged geomagnetic storm. Image: ROyal Observatory of Belgium / Solar Terrestrial Center of Excellence / Solar Influences Data and Analysis Centre
The Northern Lights could come to life in a brilliant way in places more south than usual later today.
Solar wind is always flowing from the Sun and towards Earth but coronal holes are known for releasing enhanced solar wind. Coronal holes can develop anywhere on the sun and are more common during solar minimum. One solar rotation of the Sun occurs every 27 days and coronal holes are sometimes able to last several of these. It is common to see persistent coronal holes at the north and south pole of the Sun but sometimes they can expand towards the equator of the Sun resulting in a larger region. Normally, coronal holes located near the Sun’s equator, result in faster solar wind arriving at Earth. It is common to see coronal holes produce G1-G2 geomagnetic storming levels and sometimes on rare occasions, upwards to G3 levels have been met. Dark regions on the Sun known as coronal holes are one of the main drivers of space weather now. According to the Space Weather Prediction Center, coronal holes appear as dark regions on the Sun because they are cooler than the surrounding plasma and are open magnetic field lines. The Sun’s outermost part of its atmosphere, which is known as the corona, is where these dark regions appear. The solar corona was also one of the main features of the Sun scientists were most excited to study during the past solar eclipse. You are able to notice these features in extreme ultraviolet (EUV) and soft x-ray solar images.