On Sunday night, a cluster of particles flung outwards from the sun in a Coronal Mass Ejection slammed into Earth’s atmosphere, triggering intense auroras across the world. The event made a particular impact in New Zealand, which was treated to an unusually beautiful and dazzling light show throughout the event.
According to NOAA, the geomagnetic storm ran through the first half of March 24 and was categorized as a G4 event. The last time a storm of similar magnitude hit the earth was in September of 2017.
During a Coronal Mass Ejection, enormous clouds of plasma explode off the surface of the sun during intense solar activity—often triggered by the realignment of magnetic fields in sunspots. Once ejected, the plasma—a field of high-energy charged particles—travel out into space at speeds approaching 6.7 million miles an hour. Contrary to popular belief, a CME is not a solar flare. The flares are emissions of electromagnetic radiation (i.e. light in various wavelengths), where the mass ejections are charged particles that can, themselves, emit light. While each phenomenon can cause the other, they are distinct events.
When these charged particles collide with Earth, they intract with the planet’s ionosphere and emit light—a phenomenon we call “auroras.” The Northern Lights are a famous, semi-regular aurora phenomenon that happens in high latitudes of the Northern hemisphere, where Earth’s magnetic field (the source of the ionosphere) emerges from the planet’s core at the northern magnetic pole in a relatively dense bundle.
Such geomagnetic storms are rated on a scale running from “minor” (G1) to “extreme” (G5). Extreme events can penetrate the ionosphere and impact electrical equipment. G4 storms (severe) are not as common as less intense storms, and are seen only around 100 times every 11-year solar cycle.
The Coronal Mass Ejection that caused this week’s storm is believed to have been generated by an X1-class solar flare that erupted on March 22.
