‘Interplanetary Shock Wave’ Spawns Electric-Blue Auroras

A moderate geomagnetic storm kicked up in Earth’s skies Friday morning (April 20), bringing green and rare electric-blue auroras that stretched as far south as Indiana.

The space-weather news site Spaceweather.com reported that an “interplanetary shock wave” hit Earth’s magnetic field at about 3:50 a.m. EDT (2350 on April 19 GMT), quadrupling the intensity of the flow of particles streaming from the sun toward Earth, called the solar wind. The incoming wave of material resulted in a G2-level, or moderate, geomagnetic storm, according to the National Oceanic and Atmospheric Administration’s Space Weather Prediction Center (SWPC). These types of storms can cause power grid fluctuations and have some impact on radio communications.


And they also cause enhanced auroras. This storm led to auroras possibly reaching through Canada and as far south as New York, Wisconsin and Washington state in the U.S., the SWPC said.

Spaceweather.com reported that auroras stretched as far south as six northern U.S. states in the Northern Hemisphere, and could also be seen in the Southern Hemisphere over Tasmania. (Auroras form near both the North and South Poles, although the northern ones are more well-known.)