Edgar McGregor

On Friday night, May 10, 2024, an enormous G5 solar storm struck planet Earth after five coronal mass ejections (CMEs) moving at varying speeds through the solar system converged over the planet. The aurora borealis was observed all across North America, with reports as far south as Florida, Hawai’i, Mexico, and even the Caribbean. The aurora also visited California, where onlookers in the Angeles National Forest above the marine layer we able to observe pillars of red light to the north. A Kp Index of about 8.67 or higher is needed to observe the aurora borealis with the naked eye at 34° latitude and reduced light pollution.

How does it work?

The sun goes through 11-year cycles of sunspot activity that can observed over decades by satellite instrumentation. When sunspot activity peaks, a phenomena known as a coronal mass ejections (CMEs) can occur several times per Earth day. When the 11-year cycle bottoms out, days or even weeks can pass without any CMEs from the sun.

Since the sun spins, it creates its own magnetic field just like Earth. The insides of the sun are so hot and pressurized that the magnetic field lines within the sun can become tangled up and kinked. When they kink, excess energy can get trapped in small area, and this excess energy will push outward towards the sun’s surface. If it is strong enough, it’ll blast through the sun’s surface in a massive explosion that can become larger than the planet Jupiter in a matter of minutes. These explosions are called coronal mass ejections, or CMEs for short. In the process, positively charged protons get blasted out into outer space. 

A coronal mass ejection (CME) also sends out a magnetic flux, which are shockwaves in the magnetic field. Combined with the charged protons, the two will race off into space at anywhere between 1,000,000 MPH and 5,000,000 MPH in velocity depending on how severe the CME was. Once the CMEs leave the surface of the sun, they are called solar storms. Solar storms can overwhelm the Earth’s magnetic field and excite gasses in the upper atmosphere. This process is what causes the aurora.

On Wednesday morning, May 8th at around 8:00 UTC, two CMEs ejected from the sun and began racing right towards planet Earth. Later in the day Wednesday, another two average-strength CMEs exploded from the sun, also headed in the Earth’s direction. Finally, on Thursday morning, an extremely powerful CME occurred moving much faster than the rest. When CMEs leave the sun, an entire quarter of the solar system can be impacted, so it isn’t unusual for any planet to be hit by one. What was unusual this time, however, was that all 5 CMEs converged simultaneously over planet Earth leading to what is now the strongest solar storm of the generation. This animation from the University of Reading shows what multiple solar storms converging over the Earth (black dot) looks like:

Solar storms of this magnitude have a return period of about once every 20 years. What made Friday’s event so special was that it occurred during a new moon which helped lower light levels. Additionally, a marine cloud deck in place over the coastal valleys drastically lowered light pollution in upper Eaton Canyon.

A mad rush to Mount Wilson on Saturday night by thousands of spectators hoping to catch a glimpse did not yield any result, as the solar storm had already passed. Indeed, Friday night was the only night to view the northern lights in Los Angeles County.

“The aurora borealis was a no show up from Mt. Wilson tonight [Saturday]. It was a rowdy scene, and if I had known it would be so insanely attended, I would have probably stayed home. When we finally did get out it was a funeral procession of hundreds of cars the entire way down [the Angeles Crest Highway.]”

– Facebook user

Here are some photographs of the event in and around upper Eaton Canyon:

1:08 PM, May 15th update: Following repairs, the gift store has reopened.

Last week, volunteers working at the Eaton Canyon Nature Center had a rude awakening when they discovered water pooling on the gift shop’s floor. A water leak in the walls of the nature center had soaked through onto the carpet and was threatening to damage merchandise. Quick acting by both county staff and official volunteers prevented any merchandise from being damaged. However, the gift shop will remain closed for the time being until repairs are made.

Earlier this year, the gift shop got an upgrade with a brand new countertop, new merchandise, and an improved set-up. The new countertop has not been damaged by the water leak.

In recent weeks, the California Conservation Corp has been working tirelessly to remove and replace a significant majority of Eaton Canyon’s signs between the Nature Center and the Chuck Ballard Memorial Bridge. The project has already successfully removed random blocks of concrete, sun-bleached signs that were beyond cleaning, and the set of signs by Walnut Canyon that had been an eye-sore for several years. The goal of the project was to help park visitors be better aware of the rules, learn more about the science of the natural area, and learn the proper route to Eaton Canyon Falls. Unfortunately, vandals have already hit the new signs with graffiti before the project can even be completed.

Included in the signage project is a set of new mile marker signs designed to help visitors know their location in the event of an emergency. Each sign has a specific number on them to communicate to authorities where you are. One of these signs placed within Coyote Canyon’s wash had already been pulled out of the ground by vandals.

Eaton Canyon, like many of Southern California’s hiking trails, has had problems with graffiti for years. It costs upwards of $100 per month to keep the the graffiti at bay, and this figure does not include official National Forest Service volunteers cleaning graffiti between the Chuck Ballard Memorial Bridge and the waterfall. With all the new signage in the park, it is likely the monthly cost of graffiti abatement will rise. In early February, a single vandal caused $200 worth of damage to the Eaton Canyon Natural Area. An article on the story was written here.