Solar Flare Causes Geomagnetic Storm, Aurora Expected In Northern Reaches

On Saturday, October 9, specialists at NASA’s Solar Dynamics Observatory detected a solar flare from a sunspot. Solar flares happen constantly, but this one is unique: it launched a coronal mass ejection (CME) directly toward Earth’s atmosphere.

As a result, parts of the northern hemisphere as far south as New York might be lucky enough to witness an anomalous aurora borealis between dusk October 11 and dawn October 12.

Solar flare event and what to expect

Owing to its intensity and trajectory of the CME, the flare will trigger a G2-level geomagnetic storm over our planet’s northern hemisphere beginning late Monday, October 11, and lasting into Tuesday or Wednesday. In addition to the aurora borealis (aka northern lights) spectacle, scientists predict that the flare will cause a few noticeable events throughout late Monday and into Tuesday morning:

  • Moderate fluctuations to high-latitude power grids, which could potentially trigger voltage alarms and result in damage to some transformers.
  • Mild to moderate satellite and spacecraft interference, including disorientation due to increased drag on low-Earth orbiters. Such disorientation will likely require corrective repositioning by ground control agents.
  • High-latitude radio interference resulting in high-frequency propagation fades.

The Geomagnetic Storm Scale explained

noaa geomagnetic storm alert, oct, 11, 2021

Image: NOAA


NOAA established a 5-tier geomagnetic storm scale which it uses to gauge weather systems caused by solar activity. G1 storms are ‘minor’ with minimal detected effects and a high frequency of occurrence — about 1,700 times every 11 years. G5 storms constitute the most extreme and rarest storm type, with intense, far-reaching effects that can be detected as low as Florida and southern Texas. By comparison, G5 storms occur about four times every 11 years.

What we’re experiencing on October 11 is a moderate G2 storm, which is relatively mild and occurs about 600 times in 11 years.

What creates the aurora borealis?

Aurora borealis aka northern lights. Elements of image furnished by NASA. Image_ Mura T, Shutterstock

Image: NASA/Mura T. via Shutterstock indicated the unusual northern lights show may be visible from Scotland, Northern England, and Northern Ireland in the UK, as well as Canada and the northern band of U.S., states that span from the Pacific Northwest through upper New England. Views may be visible as far down in latitude as Washington S.tate, Wisconsin, and New York.

As explained by ExWeb’s own Kristine De Abreu in Solar Storm Causes Spectacular Aurora:

 “There are two magnetic fields at play — the Earth’s and the Interplanetary Magnetic Field carried by the solar wind. While Earth’s magnetic field stays fixed over long periods (100,000s of years), the IMF fluctuates around the equinoxes, creating openings called cracks. These cracks allow particles from the solar wind to enter the magnetosphere, triggering the auroral displays. The ionization when the solar wind collides with the upper atmosphere creates a variety of colors.”

Follow along as this October solar storm develops with @NOAA or check-in with NOAA’s Space Weather Prediction Center at, which serves as the US government’s official source for space weather forecasts, watches, warnings, and alerts.