“With the development of our civilization, these events are possibly more disastrous than they used to be. That is definite,” explains Martin Connors, a professor of physics, mathematics, and astronomy at Athabasca University. With a moderate G2 geomagnetic storm heading toward Earth this weekend, observers in 18 American states from New York to Idaho are in for a special treat: the northern lights dancing far south of their usual positions. But behind the pageant, a complex ballet of sun physics and technological susceptibility is unfolding.
This weekend’s weather centers around a recent solar flare, an outpouring of electromagnetic radiation vomited out of an active sun region. Solar flares are not firecrackers but the most powerful blasts in the solar system, the biggest similar to a billion hydrogen bombs in energy release. These flares have the potential to initiate coronal mass ejections (CMEs) gigantic magnetic clouds of magnetized plasma that can shoot a billion tons of material down at Earth at a million miles an hour. If a CME happens to be aimed in our direction, as it was on the 5th of August in the morning, it’s the precursor to geomagnetic storms and to the auroral displays that so many find enthralling.
The process is beautifully violent. When CME’s energized particles interact with Earth’s magnetosphere, they trigger a chain of reactions. Accelerated electrons are fired down magnetic field lines to the poles, where they interact with oxygen and nitrogen molecules in the upper atmosphere. The consequence is a glowing light aurora borealis in the north, aurora australis in the south brushed with shades of green, red, and purple. The most common green aurora, for example, is caused by excited atomic oxygen between 120 and 400 kilometers. Different atmospheric gases and elevations determine the aurora’s characteristic color palette.
These amazing sky displays are only the visible tip of the iceberg, though. When charged particles bombard the ionosphere the layer that separates Earth from space they heat and expand the atmosphere, inducing significant impacts on today’s technology. Low Earth orbiting satellites have increased atmospheric drag, and therefore they burn precious fuel staying up. “For some of the [low Earth orbit] science missions, we saw a lowering of the [satellite’s] orbit of anywhere from dozens of meters to hundreds of meters,” NASA’s DeHart says, outlining the effect of the May 2024 superstorm. Orbits in some instances fell by as much as 400 to 600 meters, threatening both the scientific worth of the information and the operational lifespan of such satellites.
Solar storms also threaten the electronics of satellites. High-energy particles can induce “bit flips” in computer memory, crashing systems or worse, inducing satellites to go into safe mode a protective mode in which all but critical operations are disabled. Reboots aren’t always that easy; sometimes mission teams have to agonizingly reload software and hunt for hardware malfunctions. “When you enter safe mode, science [data collection] stops and you investigate what’s going on with the spacecraft,” says DeHart.
On Earth, the impact radiates outward. The G5 May 2024 storm was a wake-up call: positioning errors up to 70 meters were suffered by GPS users, particularly in the Central United States. Precision agriculture, which depended on GPS-guided tractors and implements, experienced an estimated $500 million loss for the peak planting period. The culprit was an ionospheric plasma wall that caused GPS signals to disperse and reflect, producing sudden jerks in computed positions. As the scientists put it, “These findings highlight the need for more accurate understanding of ionospheric plasma conditions, as well as software and hardware improvements, to reduce disruptions during space weather events.”
NOAA and NASA are at the forefront of space weather forecasting, with the use of a variety of ground-based sensors and satellites to track the sun’s moods. The new SWFO-L1 mission, launching in 2025, will supplement DSCOVR and the GOES satellites at Lagrange Point 1 a million miles ahead of the solar wind to serve as an early warning of solar storms on their way. These real-time observations matter: too little warning of just one or two days before a CME hits means operators have to move fast to protect satellites, divert flights, and defend power grids.
The risks are more than hypothetical. The 1859 Carrington Event, the largest geomagnetic storm in history, upset telegraph communications across the globe and colored aurorae at the equator. If a similar storm were to happen today, the National Academies of Sciences estimates it would cost up to almost $2 trillion, taking out power for 20–40 million Americans for weeks or even years. Even the 1989 Quebec power blackout caused by a less intense storm took out six million individuals for nine hours. The G2 storm later on this weekend should be manageable, with the effect being mostly limited to technology infrastructure. But as the sun moves toward its solar maximum in its 11-year cycle, both the number and strength of such events will increase. To amateur astrophysicists and science buffs, the auroras are a visually striking reminder of the position our planet occupies in an active solar system. To policymakers and engineers, they are a clarion call to make the technologies that support contemporary life more robust.
