Butterfly-Shaped Hole in the Sun Could Spark Solar Storms Worldwide This Weekend

A colossal butterfly-shaped coronal hole has opened up in the Sun's atmosphere, and the southern opening is spewing a stream of solar wind towards Earth that may spark auroras after September 14. The stretchy structure, which spans some 310,000 miles (500,000 kilometers), could drive geomagnetic activity powerful enough to produce auroras visible from the middle of the world to its higher latitudes this weekend. Predictions are for minor to moderate storm levels, and clear skies will give observers a great chance of seeing vivid auroras.

Geomagnetic Storm Forecast: Butterfly-Shaped Coronal Hole May Spark Auroras Across Hemispheres Sept. 13–14”

According to Forbes, the U.K. Met Office has highlighted that active to G1 conditions are likely, with the possibility of a G2-level storm on Sept. 13–14. Auroras will peak at G1, according to NOAA, but could be more attractive if solar winds are in line with Earth's magnetosphere to produce bursts of green, red and purple aurora.

The authors of the study point out that the event overlapped with the Russell-McPherron effect, which actually enhances geomagnetic activity around equinoxes as Earth's inclination becomes more favourable for effective solar wind-magnetosphere interaction. Research indicates that storms occur by a factor of two during the equinox months, so those increase aurora odds.

If G2 levels are reached, auroras may illuminate skies across Canada, Alaska, Scandinavia, and northern U.K. regions, with southern sightings possible in Tasmania or New Zealand. The storm's true intensity will depend on solar wind conditions upon arrival, but experts say the butterfly-shaped hole makes this weekend especially promising for aurora chasers.