It started with an explosion that lasted for over three hours, a sustained eruption by sunspot 4204 of the Sun’s equator on August 30. The M2.7-class flare among the strongest classes of solar flares propelled a gargantuan cloud of magnetized plasma into space. NASA’s Solar and Heliospheric Observatory later confirmed the coronal mass ejection, or CME, was headed toward Earth. But within a day, they found this wasn’t an ordinary solar storm. Space weather physicist Dr. Tamitha Skov explained on X that two CMEs had burst in rapid succession, with the second, more massive one catching up with the first before it landed on Earth.
The larger one catches up with the smaller one just ahead of Earth, she explained how researchers make what they term a “cannibal CME.” The two cloud-like plasma collides and creates a more turbulent and intense storm front, able to pack a harder punch to Earth’s magnetic field. When it eventually appears late on the 1st of September as a conjoined mass, NOAA Space Weather Prediction Center forecasters anticipate a geomagnetic storm potentially reaching G3 intensity at its maximum on the five-point NOAA scale, with a possibility of going up to G4.
These kinds of disturbances shrink and deform the magnetosphere temporarily so that high-energy charged particles penetrate deeper into the atmosphere. They then meet oxygen and nitrogen molecules there, creating the glistening curtains of green, red, and purple color called auroras. This storm’s peak intensity can bring auroral visibility as far south as its typical latitude, maybe blessing skies over as many as 18 U.S. states from Montana and Alaska to New York and Illinois if cloud cover and light pollution allow. NOAA’s Kp index prediction says the best viewing opportunity will be early morning on Sept. 2, when geomagnetic activity could peak at Kp 6.67.
The phenomenon comes on the heels of increased solar activity near the end of the present solar maximum, the approximate 11-year peak of the Sun’s activity cycle.
Sunspots, the dark, magnetically active regions on the Sun’s surface, during this time grow in number, and the rate of flares and CMEs increases dramatically. “During solar maximum, the number of sunspots, and therefore, the amount of solar activity, increases,” said Jamie Favors, director of NASA’s Space Weather Program. This uptick brings both scientific opportunity and tangible risk to modern infrastructure.
The superstorm of May 2024 highlighted those dangers. That G5-class event the most powerful in over two decades not only colored auroras over most of the world but also interfered with GPS navigation, caused damage to satellites, and produced two new temporary radiation belts around our planet. Information from NASA’s Colorado Inner Radiation Belt Experiment CubeSat showed one of the belts held an unprecedented number of protons, a trend described by lead author Xinlin Li as “really stunning.” The belts lasted for months and threatened spacecraft flying in geostationary transfer orbits. Geomagnetic storms also produce strong electric currents in long Earth conductors, saturating transformers and causing blackouts. The March 1989 storm notoriously left six million Quebec residents without power for nine hours. Just last February 2022, a geomagnetic storm generated such atmospheric drag that 38 newly deployed Starlink satellites re-entered and broke apart.
Satellites are particularly susceptible at solar maximum, when high ultraviolet and X-ray radiation heats and inflates the top of the atmosphere, causing additional drag on spacecraft in low orbit. Penetrating high-energy particles also tend to penetrate satellite shielding, burning electronics and pitting solar panels. Ionospheric irregularities during geomagnetic storms can induce signal delay, dropouts, and positional errors for navigation and communication networks.
Cannibal CMEs introduce another degree of complexity. Their merged shock fronts may compress the magnetosphere more abruptly than individual CMEs, amplifying geomagnetically induced currents and the likelihood of both spaceborne and ground-based disruptions. Designers of spacecraft and power grid infrastructure who are engineering the safety of such technology need to know about such events so that they can effectively employ mitigation.
Despite scientists’ belief that the ongoing solar maximum is now over, recent weeks have witnessed a fierce surge in activity, including a record solar tornado in late August.
Inasmuch as the Sun can continue to release massive storms during its decline stage of the cycle, institutions like NASA and NOAA are intensifying observation efforts. The Parker Solar Probe, which will fly by its closest-ever approach in December 2024, will enable scientists to observe the creation of space weather events such as the one headed towards Earth. Millions of North American residents for now can look upwards this Labor Day evening, seeing an unprecedented spectacle forged through violent solar activity and a reminder that the same forces which bring color to the skies can defy technology made part of daily life.
