Volcanic Dust Paints Duluth’s Sunsets


Fiery colors illuminate the western sky a half hour after sunset last night (August 29) over Rice Lake Township. Volcanic dust and gas high in the atmosphere have deepened the colors of twilight the past week or two. Photo: Bob King / News Tribune

I hope some of you found our featured variable star Eta Aquilae under last night’s clear sky. Look again in a few nights and it will have noticeably faded. Maybe you’ve been keeping an eye on sunsets as well. Have you noticed that the twilight sky in the west has looked more colorful lately? Clouds of volcanic dust and sulfur dioxide sent sky high from the July and August eruptions of three volcanoes in Alaska’s Aleutian Islands are the reason why. The most recent, Kasatochi, shot plumes of ash and gas 45,000 feet high into the stratosphere.


The Okmok volcano (pictured above) erupted in July in the Aleutians launching dust into the atmosphere. Dust and gas from this eruption and those of the Cleveland and Kasatochi volcanoes have been responsible for our more intense twilight colors. Photo: Jessica Larson, AVO/UAF-GI

This abundance of volcanic aerosols gives the setting sun new material for flaunting its colors, like a kid with a new set of markers and fresh pad of paper. In addition to color, I’ve also noticed subtle, grey bands and streaks of dust low in the west after sunset. While the intensity of the twilight hues doesn’t come close to those we experienced during the 1991 Mt. Pinatubo eruption, that could change depending on further activity and upper level winds. To find out more, check out the updates from the Alaska Volcano Observatory. And if you’re out around 8:15-8:30 p.m. and have a good horizon view to the west, you should be able to find Venus too, beaming low through the haze.


Looking east at dawn around 5 a.m. Friday morning August 29. Orion and his three Belt stars just clear the treetops to the right. Pollux and Castor in Gemini the Twins are the two bright stars atop on another in the left half of the frame. The constellations of winter are returning for both insomniacs and early risers. Photo: Bob King / News Tribune