How does the strong solar storm that caused the northern lights compare to previous storms?
(FOX40.COM) — In early May 2024, a strong solar storm on the Sun sent a burst of plasma and magnetic field directly toward the Earth, causing the northern lights to appear in many places where they normally never appear.
Stargazers around the world were treated to a rare event that had only happened for the fifth time in 165 years, the highest-scale geomagnetic storm possible on the Sun directly hitting the Earth.
Northern lights vs. southern lights, what’s the difference?
Although strong storms regularly happen on the Sun, not all of them eject material toward the Earth.
The NOAA Space Weather Prediction Center rates these storms from 1-5, and May’s event was rated a G5. Observations on the data show how that storm compared to the previous four that reached Earth.
On May 22, NOAA released more information about the storm earlier that month that helps compare it to previous strong storms that hit Earth, which did so in October 2003, March 1989, May 1921 and September 1859.
The Disturbance Storm Index (DST) is a number that helps scientists measure how strong a solar storm is. It’s measured by magnetic sensors placed around the equator of the earth.
The data shows the intensity of a specific type of current, the ring current, that circles the Earth during a storm. The more negative the value, the stronger the storm.
Why do the colors of the northern lights change?
May’s storm was stronger than the one in 2003, but the three storms prior to that one were even stronger.
The second number NOAA released on these storms is the Ap-index, a number derived from averages during eight three-hour periods during the day.
For each period, scientists use a K-value, which is a measure of geomagnetic activity during that time.
Missed the northern lights? Planets to align in the sky this summer
The K-values are converted to a different scale to make them easier to average. The average of these 8 values gives the Ap-index for the day. Higher Ap-values indicate more geomagnetic activity on that day.
May’s storm reached higher on the Ap-index than the prior two storms, and there is no data for this index on the storms from 1921 and 1859.
Although the public may be treated to a dazzling display of lights across the skies, solar storms can affect satellite operations, communication channels and power grids, and the two indexes are key for scientists to understand and predict the impact of the storms on Earth.
Copyright 2024 Nexstar Media, Inc. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.
For the latest news, weather, sports, and streaming video, head to FOX40.
