“For more than 30 minutes, the local magnetic field oscillated like a sine wave.” a magnetic anomaly,” reports Stuart Green, who operates a research-grade magnetometer in his backyard in Preston UK.
Space physicists call this phenomenon a “pulsation continuous” or “Pc” for short. Imagine blowing across a piece of paper, making it flutter with your breath. Solar wind can have a similar effect on magnetic fields. Pc waves are essentially flutters propagating down the flanks of Earth’s magnetosphere excited by the breath of the sun. During more active phases of the solar cycle, these flutters are easily lost in the noise of rambunctious geomagnetic activity. But during the extreme quiet of Solar Minimum, such waves can make themselves “heard” like a pin dropping in an silent room.Magnetic observatories around the world detected the wave on June 23, 2020. Credit: INTERMAGNET
Earth’s magnetic field was so quiet on June 23rd, the ripple was heard all around the world.INTERMAGNET‘s global network of magnetic observatories picked up wave activity at the same time from Hawaii to China to the Arctic Circle. There’s even a hint of it in Antarctica.from geomagnetic observatories around the world.
Pc waves are classified into 5 types depending on their period. The 10-minute wave on June 23rd falls into category Pc5. Slow Pc5 waves have been linked to a loss of particles from the van Allen radiation belts. Energetic electrons surf these waves down into Earth’s atmosphere, where they dissipate harmlessly.
With Solar Minimum in full swing, there’s never been a better time to study these waves. Keep quiet … and stay tuned for more.