Geomagnetic storm may bring the auroras back to Tri-State on Thursday, Friday

A severe geomagnetic storm will take place on Thursday and Friday, and it could bring another aurora show to the Evansville area.

The Space Weather Prediction Center on Wednesday said a G4-level storm was expected, and that the auroras "may be seen as low as Alabama and northern California." It's the result. SPWC officials said, of a coronal mass ejection that "blasted from the sun at over 2.5 million mph Tuesday."

The auroras are natural light shows that develop as "Earth's magnetic field redirects (solar) particles toward the poles through a process that produces a stunning display of rays, spirals and flickers."

There are some less pleasant side effects of a severe geomagnetic storm, the SWPC noted, such as disruption to GPS navigation systems and high-frequency radio propagation.

But as happened in the Evansville area in May, it also has the potential to produce a light show that's unusual for these parts.

The SWPC offered these tips on seeing the auroras:

• Today’s digital cameras can often capture elements of the aurora even if the human eye cannot detect it.
• The best chances to see the aurora include clear skies, dark skies away from city lights to the north, and less than full moon (which is currently the case).
• The best times to see the aurora now would be within 2-3 hours and either side of local midnight.

USA TODAY reported earlier this week that "people across Earth can expect more frequent and brighter northern lights to grace the sky as the sun nears the height of its 11-year cycle, making electromagnetic activity a more common occurrence.NASA said the sun is expected to reach the peak of Solar Cycle 25 in 2025 ."

The G4 designation for the storm is the second-highest on the SWPC scale, which ranges from G1 (minor) to G5 (extreme). On the low end, weak power grid fluctuations can occur. When you get to the high end, extreme storms can cause "widespread voltage control problems" as well as blackouts and transformer damage.

"Our best guess of intensity potential for the resultant geomagnetic storm is that G4 or greater levels are feasible," an agency notice said. "However, the strength of the geomagnetic storm will depend upon the strength and magnetic orientation of the (coronal mass ejection), which we won’t know with any certainty until it arrives at two primary spacecraft located 1 million miles from Earth."

This article originally appeared on Evansville Courier & Press: Geomagnetic storm may bring the auroras back to Tri-State on Thursday, Friday