Aurora watchers awed over weekend as solar storm collides with Earth

Observers of the night sky were treated to a rare show this past weekend, May 10 to 12, as the most powerful solar storms in two decades threw billions of tons of charged particles out into space, eventually colliding with our planet’s magnetosphere. 

A G5-rated solar storm (on the NOAA Space Weather Scale), the strongest level of geomagnetic storm that ‘space weather’ scientists measure, erupted from the sun last week and reached Earth on Friday. The last G5 storm was in 2003.

Aurora borealis, May 10, 2024 over Moose Jaw (Gordon Edgar)

Aurora borealis May 10 2024 by Wendell Gillert

Solar activity can be compared to a bubbling pot, and sometimes it boils over — from sunspots that can be dozens of times the size of our planet. 

When that happens, charged particles travelling at speeds up to 72 million kilometers per hour are hurled out into space. When they reach Earth, the planet’s magnetic field deflects the charged particles around us, but some energy is still dumped into the upper layers of the atmosphere, between 80 and 700 kilometers above the ground. 

We see that energy as light. 

Aurora borealis May 10 2024 by Wendell Gillert

The aurora borealis is a constant, ongoing phenomenon, but storms make them far more visible through a combination of sheer energy and momentum. When storms push more charged particles deeper into the atmosphere, they interact with gases like hydrogen, oxygen, and nitrogen to produce greens, reds, blues, and the entire range that the combination of those colours makes. 

Aurora borealis May 10 2024 by Gordon Edgar

The space weather this weekend was enough to make the Northern Lights visible to the naked eye as far south as California. The dancing shapes and patterns reflect the lines of Earth’s magnetic field, the density, composition, and flow of the upper atmosphere, and the variations in the solar wind itself. 

When solar storms are this intense, it is possible for their energy to affect radio communications, power grids, and other electrical infrastructure. However, major disruption and damage is rare. 

Aurora borealis May 10 2024 by Gordon Edgar