Global Magnetic Anomaly Detected During Deep Solar Minimum

A global magnetic anomaly was detected on June 23, with experts using magnetometers, a device that measures magnetism, noticing an unusual wave appear in their data. This wave appeared at a time when there should be little to pick up on.

Earth's magnetic field is generated by its liquid iron core and protects the planet from the solar wind—the stream of charged particles that comes from the sun. The magnetic field interacts with these particles and when there is an influx, magnetometers can detect these anomalies.

Activity on the sun is currently at its lowest point of its 11-year cycle, a phase known as the solar minimum. The current solar minimum is one of the deepest since the start of the Space Age, with activity on the surface of the sun quieter than normal. Because of this, there is little change to the magnetic field for instruments to pick up on., a website dedicated to the sun-Earth environment, first reported the anomaly. Stuart Green, from Preston, U.K., who operates a magnetometer, told the site he was surprised when his instruments "picked up an anomaly."

"For more than 30 minutes, the local magnetic field oscillated like a sine wave," he is quoted as saying. "There was nothing—no uptick in the solar wind speed or other factors that might explain the disturbance." says this disturbance was noticed around the world, with a global network of observatories picking up the anomaly at the same time. What caused the anomaly is believed to be a pulsation continuous (Pc), the website notes.

William Brown, from the British Geological Survey's Geomagnetism Team, told Newsweek they had recorded a "wiggle" in their magnetic observatory measurements. He said the last notably active period was at the end of March, and that it had been "very quiet" recently. "This is excellent for my work," he said. "I'm interested in the magnetic fields generated in Earth's core and the rocks of our crust, and we get the best measurements when there is least activity originating from the Sun to interfere."

Pc waves are very slight fluctuations in Earth's magnetic field that can tell us how the field is interacting with the solar wind. This can help provide a better understanding of the physical properties of the magnetic field and solar wind. During periods of heightened solar activity, Pc waves are far more difficult to detect.

There are five different types of Pc waves. This latest one recorded is known as Pc5 and is associated with particles from the van Allen radiation belts—a zone of energetic charged particles held in place by Earth's magnetic field.

"Earth's outer radiation belt is a region containing electrons that are trapped by the Earth's magnetic field," Claire Watt, who studies space weather at the University of Reading, U.K., told Newsweek. "The electrons circulate the Earth with bouncing motions, but these motions happen at velocities very close to the speed of light. As a result, electrons can make a circuit of the Earth in only 10-15 minutes, which is the same as the period of the Pc5 pulsations shown on the space weather site."

Brown said there is plenty to learn from Pc waves. "Pc waves are a bit like the standing waves that result when you hit a drum skin, you get different sounds with different shaped and sized drums, and hitting harder or softer for example, and you can tell something about the source by listening to the sound created," he said.

"I'm not surprised people are seeing beautiful clear examples of Pc5 waves right now, they're much easier to observe when the solar activity is quite quiet," Watt said.

Solar activity and erupting prominences captured by NASA. NASA Goddard