While last month’s solar eclipse was an unforgettable events for many Americans, most didn’t realize the sun had another trick up its sleeve. The first week of September saw a massive geomagnetic storm raging over the northern United States and southern Canada.  While the storm proved harmless to people and electrical grids, it did treat many to a rare sighting of the northern lights, or aurora borealis.

What is a Geomagnetic Storm?

Just as lightning storms are caused by a buildup of static electricity in the atmosphere, a geomagnetic storm is the result of an influx of magnetism in our atmosphere. But where does all this magnetism come from? The answer lies about 93 million miles away—the sun.

According to the National Oceanic and Atmospheric Administration (NOAA), the same folks who predict hurricanes, “a geomagnetic storm is a major disturbance of Earth's magnetosphere that occurs when there is a very efficient exchange of energy from the solar wind into the space environment surrounding Earth.” In other words, if the sun gives out more magnetism than Earth is used to, it causes a build-up in our planet’s atmosphere.

In this particular case, a massive solar flare erupted earlier this month. In fact, it was the most powerful solar flare in the last 12 years! This burst of magnetic energy and radiation was expelled from the sun and made a beeline for Earth where it did battle with our own magnetic field.

What are the Effects of a Geomagnetic Storm?

Just like other types of storms such as hurricanes, geomagnetic storms are categorized by their intensity. NOAA’s scale ranks a G5 is the most extreme, while a G1 is cause for the least concern. Last week’s storm raged as a middling G3. While it’s true that more powerful storms can have devastating effects, this storm was rather mild. In some case, geomagnetic storms can cause massive electrical and radio outages, this storm’s only lasting effect was a stunning aurora.

Typically reserved for the polar extremities of our planet, the northern lights are in reality millions of charged particles riding the solar wind and encountering Earth’s magnetic field. Once excited, this particles produce brilliant spectacles of dancing, swirling lights in the night sky. The reason they are typically only seen at the poles is because this is where our magnetic field is concentrated. However, because the geomagnetic storm brought so much more magnetic energy to the Earth’s atmosphere, the northern lights were able to stretch much farther south. Some predictions called for them to be visible in Missouri!

Whether we realize it or not, magnets and magnetism are a huge part of our day-to-day life. If not for Earth’s magnetic field, our planet couldn’t sustain life. Learn more about all the amazing ways magnets impact our life by checking on the rest of our blog.