Late Friday morning, the Space Weather Prediction Center recorded a “severe” geomagnetic storm.

According to the SWPC, a coronal mass ejection (CME) was ejected from the Sun on Tuesday. The CME just reached Earth on Friday.

According to the SWPC, the storm was rated “G4,” which is considered severe. By comparison, the storm that caused the aurora to be visible across the Northeast was rated G5, the highest level on the scale that runs from G1 to G5.

However, the arrival of the coronal mass ejection alone is no guarantee that an aurora will occur. The coronal mass ejection has a magnetic field, like a magnet. And just as opposite sides of magnets attract and like sides repel, the coronal mass ejection must be properly aligned relative to Earth's magnetic field. Data from the SWPC suggests that this may not be the case, which could mean that despite a severe geomagnetic storm, no aurora would be visible.

The fields can fluctuate, as can the strength of the storm. As the CME continues to impact Earth, more information will become available.

The effects this coronal mass ejection could have on Earth include “an increased possibility of anomalies or impacts on satellite operations” and “more frequent and prolonged periods of GPS degradation,” according to the SWPC.