Bright green curtains of aurora borealis swept across Alaska skies on the night of April 18-19, bringing residents and visitors to popular viewing locations in Fairbanks and Kodiak.

The displays matched forecasts from the University of Alaska Fairbanks Geophysical Institute, which predicted active auroral activity visible overhead from Utqiaġvik to Anchorage and Juneau under clear skies. Peak activity occurred around midnight.

Kodiak photographer Kris Luck captured images of the lights over the island and shared them online. In Fairbanks, residents posted photos and descriptions of the shifting green displays visible to the naked eye.

The Geophysical Institute's aurora forecast indicated high activity levels for the night. Explore Fairbanks real-time aurora data confirmed the elevated readings for April 18-19.

Fairbanks viewing locations including Chena Lakes Recreation Area and Cleary Summit likely drew crowds based on the forecast, though specific attendance numbers were not available. The city sees aurora on average four out of five clear nights, according to Alaska.org.

Visitors staying three nights in Fairbanks under clear skies have better than 90 percent odds of seeing the northern lights, the Geophysical Institute reports.

Cloud cover can block views even during active periods. Kodiak's marine climate brings frequent clouds that may have limited visibility for some observers despite the forecast.

The displays provided a boost for tourism businesses during the shoulder season between winter and summer. No disruptions to fisheries, oil and gas operations, or other activities were reported.

Aurora activity follows an 11-year solar cycle. The current solar maximum period brings more frequent and intense displays across Alaska.

The lights occur when charged particles from the sun interact with gases in Earth's upper atmosphere. Green light comes from oxygen molecules about 60 miles above the surface. Red aurora, less common, appears at higher altitudes.

Alaska's northern location and dark winter skies make it one of the best places on Earth to view aurora. Fairbanks sits directly under the auroral oval, the ring-shaped zone where displays occur most often.

The University of Alaska Fairbanks Geophysical Institute maintains an aurora forecast at www.gi.alaska.edu/monitors/aurora-forecast. The forecast predicts activity levels and visibility for locations across the state.

Explore Fairbanks provides a real-time aurora tracker at www.explorefairbanks.com showing current conditions and recommended viewing spots around the Fairbanks area.