On July 7th, a crack appeared in the Earth's magnetic field, which remained open for about 14 hours, enabling intense solar winds to stream through the opening, causing a geomagnetic storm that created some very spectacular aurora.
A co-rotating interaction region (CIR) from the Sun caused the fissure in the magnetosphere. CIRs are large-scale plasma structures produced in the low and mid-latitude areas of the heliosphere — the region around the Sun that contains the solar magnetic field and solar winds – when rapid and slow-moving streams of solar wind meet.
Similar to coronal mass ejections (CMEs), coronal ionization regions (CIRs) are ejected from the Sun toward Earth and may include shockwaves and compressed magnetic fields that generate turbulent space weather, which typically manifests as beautiful aurorae.
This one struck the Earth's magnetic field early on July 7 and triggered a G1-class geomagnetic storm. According to Spaceweather.com, National Oceanic and Atmospheric Administration (NOAA) experts believe a CME was embedded in the solar wind prior to the CIR.
Cracks in the magnetic field of the Earth are normal. The magnetic field serves as a protection against solar storms produced by the Sun. It was previously believed that they opened and closed pretty fast, but we now know that they remain open for hours.
"We've discovered that our magnetic shield is draughty, like a house with a window stuck open during a storm," said Harald Frey, lead author of a study on this discovery back in 2003.
"The house deflects most of the storm, but the couch is ruined. Similarly, our magnetic shield takes the brunt of space storms, but some energy slips through its cracks, sometimes enough to cause problems with satellites, radio communication, and power systems."
The Sun is approaching its most active time in the solar cycle (July 2025) and is already abnormally energetic for so early in the cycle. Your odds of viewing the aurora are now rather excellent, but they will continue to improve over the following three years.
Reference(s): SpaceWeather
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