Tennesseans saw a rare display of the Northern Lights after a powerful G4 geomagnetic storm pushed the auroral oval south. Vanderbilt Dyer Observatory director Billy Teets explained that energetic electrons from the sun interact with Earth's magnetic field and atmosphere, and oxygen emissions produce the red and green colors. We are near solar maximum in the sun's ~11‑year cycle, which makes strong storms and southern aurora sightings more likely. NOAA currently does not forecast another storm of similar strength in the coming nights.
Why the Northern Lights Reached Tennessee: Vanderbilt Astronomer Explains the G4 Storm
Tennesseans saw a rare display of the Northern Lights after a powerful G4 geomagnetic storm pushed the auroral oval south. Vanderbilt Dyer Observatory director Billy Teets explained that energetic electrons from the sun interact with Earth's magnetic field and atmosphere, and oxygen emissions produce the red and green colors. We are near solar maximum in the sun's ~11‑year cycle, which makes strong storms and southern aurora sightings more likely. NOAA currently does not forecast another storm of similar strength in the coming nights.
08:20 PM, 11/15/2025Science
Northern Lights Over Tennessee: What Happened and Why
Tennesseans were treated to a spectacular display of the Northern Lights on Tuesday and Wednesday night. News 2 spoke with Billy Teets, director of Vanderbilt University's Dyer Observatory, who explained what produced the aurora and why it was visible so far south.
How the aurora is formed
Teets said the lights occur when energetic particles — primarily electrons — emitted by the sun strike Earth's magnetic field and are channeled toward the polar regions. As those particles collide with atoms and molecules in the upper atmosphere, they transfer energy and cause the gases to emit light. Different gases and different altitudes produce different colors: oxygen produces green (commonly ~100–250 km altitude) and red (at higher altitudes), while nitrogen can produce blue and purple hues. Teets compared the process to how electricity excites gases in a neon lightbulb.
Why Tennessee saw the aurora
The key factor this week was the strength of the geomagnetic storm. According to NOAA's Space Weather Prediction Center, Tuesday's storm was classified as a G4 (severe) on the G-scale that runs from G1 to G5. Strong geomagnetic storms push the auroral oval farther from the poles, allowing people much farther south — even into states such as Tennessee and Alabama — to see the lights.
Teets also noted that the sun is near solar maximum in its roughly 11-year cycle. Solar maximum brings more frequent and intense solar storms, so sightings become more likely. While aurorae can occur at solar minimum, powerful storms are less common then.
What to expect next
The Space Weather Prediction Center has not forecast another storm of G4 strength in the next few nights, so if you missed this display it may be some time before Tennessee sees aurora again. Teets said Tennessee has seen auroral displays three times in the past two years, reflecting the increased solar activity now underway.
Bottom line: A powerful solar storm and current solar maximum combined to push the aurora far enough south for many in Middle Tennessee to enjoy a rare and beautiful show.