- Massive solar plasma ejections fueled a widely viewable northern lights display Tuesday.
- A third coronal mass ejection is due to arrive on Earth around midday Wednesday.
- Geomagnetic storms can also disrupt electrical grids and air traffic communications.
Massive solar plasma ejections led to a rare chance to view the northern lights phenomenon across the continental U.S. Tuesday evening including most of Utah.
For those who missed the multi-color show, also known as the aurora borealis, meteorologists say continued coronal mass ejections could bring the display back Wednesday.
Coronal mass ejections or CMEs are huge bubbles of coronal plasma threaded by intense magnetic field lines that are ejected from the sun over the course of several hours, according to NASA. CMEs often look like huge, twisted rope, which scientists call “flux rope.”
CMEs can take from 15 to 18 hours to reach Earth and when they do, a major disturbance of Earth’s magnetosphere can occur when there is a very efficient exchange of energy from the solar wind into the space environment surrounding Earth, according to the National Oceanic and Atmospheric Administration. Those storms result from variations in the solar wind that produce major changes in the currents, plasmas and fields in Earth’s magnetosphere.
While two CMEs arrived Tuesday, triggering the geomagnetic storms that create the aurora borealis effect, a third is expected to reach Earth around midday Wednesday.
And, according to an explanation posted to X by Shawn Dahl, service coordinator at the NOAA Space Weather Prediction Center, it is the largest of the three recent CMEs.
“That was the most energetic and strongest of this activity out there in space,” Dahl said. “It was traveling significantly faster than these other two, and we think that’s going to pack even a stronger punch than what we’ve already experienced.”
NOAA uses a five-tier space weather scale to rank the size of geomagnetic disturbances which, besides providing dazzling overhead light effects, can create serious issues for Earth-bound infrastructure including power grids, air traffic control radio communications and even radio and GPS systems.
While Tuesday’s geomagnetic activity reached the G4 level, NOAA is predicting Wednesday’s event will hit G3.
Some cloud cover is expected over Utah on Wednesday but those looking to monitor further northern lights activity will have their best chances between sunset and midnight.
What causes the different colors of northern lights?
Different colors are created when charged particles in the solar winds collide with gases in the Earth’s atmosphere. Here’s a breakdown from the Canadian Space Agency:
- Green: Green is the most common color seen from the ground and is produced when charged particles collide with oxygen molecules at altitudes of 60 to 120 miles
- Pink and dark red: Occasionally, the lower edge of an aurora will have a pink or dark red fringe, which is produced by nitrogen molecules at altitudes of around 60 miles
- Red: A bit higher in the atmosphere (at altitudes of 120 to 250 miles), collisions with oxygen atoms produce red auroras.
- Blue and purple: Finally, hydrogen and helium molecules can produce blue and purple auroras, but these colors tend to be difficult for our eyes to see against the night sky.