Tone and Charles Deehr in Fairbanks, October 2021. Both photos courtesy Charles Deehr. 3. (Courtesy Photo / Charles Deehr)

Alaska Science Forum: Red aurora rare enough to be special

In decades of sky-watching in the north, he has seen a few red auroras, but not many.

By Ned Rozell

Charles Deehr will never forget his first red aurora. On Feb. 11, 1958, Deehr was a student at Reed College in Portland, Oregon. He asked a Fulbright student from Norway named Tone to the Portland Symphony that night.

They went for a stroll on a golf course after the concert. Looking past the treetops, they noticed the sky was blood red.

People as far south as Mexico saw the red sky that night. Some thought Martians. Others thought Christ was visiting for the second time. In Portland, people thought a forest fire was causing the glow.

Deehr knew better, because he was studying the physics of Earth and space. Under the crimson sky, he was sure of two things: he and Tone were seeing a great red aurora, and he would ask her on another date.

A rare red aurora over Alaska in February 1958. (Courtesy Photo / Geophysical Institute)

A rare red aurora over Alaska in February 1958. (Courtesy Photo / Geophysical Institute)

The Deehrs have now been married 61 years. Charles — Chuck to his friends — was a space-physicist and aurora forecaster at the University of Alaska Fairbanks for most of that time. In decades of sky-watching in the north, he has seen a few red auroras, but not many.

Fringes of red and blue hanging from aurora curtains — the result of particles from the sun reacting with nitrogen in the upper atmosphere — happen often, but the great displays that flood the sky with diffuse red light are rare.

Red aurora displays happen so high in the sky they are often the only form of aurora ever seen by people in the mid-latitudes.

In A.D. 37, a great red aurora showed itself to the citizens of Rome. Those in London gazed up at a red sky in September 1839. A blazing display in 1938 lit the sands of the Sahara Desert in northern Africa. Deehr and his date witnessed one of the most spectacular displays in 1958. Others have happened in 1989, 2000 and 2001.

Great red auroras are rare because they require a perfect mix of heavenly conditions.

“To get a pure red aurora, you need two things from the sun,” Deehr said. “Lots of solar flares with ultraviolet radiation to heat the Earth’s atmosphere, and lots of coronal mass ejections to power the Earth’s magnetospheric generator of aurora.”

Charles and Tone Deehr with their daughter Tina near Dawson City, Yukon in 1961. (Courtesy Photo / Charles Deehr)

Charles and Tone Deehr with their daughter Tina near Dawson City, Yukon in 1961. (Courtesy Photo / Charles Deehr)

The green aurora northerners enjoy almost every dark night is a product of particles cast off by the sun that stream outward into space. This solar wind takes a day to two to reach Earth. It flows over the planet and reacts with Earth’s magnetic field. In the upper atmosphere, this electrical discharge reacts with gases, causing them to glow in the same way electricity fires up a neon light.

Green auroras occur at about 60 miles above Earth. Pure red auroras are much higher, from about 200 to 300 miles up, which allows people closer to the equator to see them. An important gas remaining at that altitude is oxygen, and electrons that excite the oxygen atoms there produce a red light as pure as a laser.

Cameras and phones that can capture more light wavelengths than our eyes sometimes show red in aurora photos in which the photographer only saw greens. Red auroras have to be 10 times as bright as green auroras for us to see that color with the naked eye.

Red auroras are unpredictable, but in the past they have tended to bunch themselves around periods when the solar cycle — an 11-year period of sun activity — features lots of solar activity.

Today, Chuck Deehr is a professor emeritus at the Geophysical Institute of the University of Alaska Fairbanks. He doesn’t expect to ever see a red aurora as brilliant as the night of Feb. 11, 1958, but some things — like a first date that leads to a 63-year partnership, four daughters, and seven grandchildren — happen only once in a lifetime.

• Since the late 1970s, the University of Alaska Fairbanks’ Geophysical Institute has provided this column free in cooperation with the UAF research community. This year is the institute’s 75th anniversary. Ned Rozell, ned.rozell@alaska.edu, is a science writer for the Geophysical Institute.

More in News

FILE - Tara Sweeney, a Republican seeking the sole U.S. House seat in Alaska, speaks during a forum for candidates, May 12, 2022, in Anchorage, Alaska. Sweeney's campaign manager said, Wednesday, June 22, 2022, that the campaign did not plan to sue over a finding released by Alaska elections officials stating that she cannot advance to the special election for U.S. House following the withdrawal of another candidate. (AP Photo / Mark Thiessen, File)
Alaska Supreme Court ruling keeps Sweeney off House ballot

In a brief written order, the high court said it affirmed the decision of a Superior Court judge.

President Joe Biden signs into law S. 2938, the Bipartisan Safer Communities Act gun safety bill, in the Roosevelt Room of the White House in Washington, Saturday, June 25, 2022. First lady Jill Biden looks on at right. (AP Photo / Pablo Martinez Monsivais)
President signs landmark gun measure, says ‘lives will be saved’

The House gave final approval Friday, following Senate passage Thursday.

Three people were arrested over several days in a series of events stemming from a June 16 shoplifting incident, with a significant amount of methamphetamine seized. (Michael Penn / Juneau Empire)
Shoplifting investigation leads to arrests on drug charges

Significant amounts of drugs and loose cash, as well as stolen goods, were found.

Ben Gaglioti, an ecologist at the University of Alaska Fairbanks, stands next to a mountain hemlock tree damaged in winter on the outer coast of Glacier Bay National Park in Southeast Alaska. (Courtesy Photos / Ned Rozell)
Alaska Science Forum: Bonsai trees tell of winters long past

By Ned Rozell A GREEN PLATEAU NORTH OF LITUYA BAY — “These… Continue reading

This photo shows a return envelope from the recent special primary election for Alaska's lone seat in the U.S. House of Representatives. On Friday, a judge sided with the state elections office on a decision to omit fifth-place finisher Tara Sweeney from ballots in the special general election. Al Gross, who finished third in the special primary, dropped out of the race, creating confusing circumstances ahead of Alaska's first ranked choice vote. (Ben Hohenstatt / Juneau Empire)
Judge rules Sweeney wont advance to special election

Decision has Sweeney off the ballot for special election.

It's a police car until you look closely and see the details don't quite match. (Juneau Empire File / Michael Penn)
Police calls for Saturday, June 25, 2022

This report contains public information from law enforcement and public safety agencies.

A Princess Cruise Line ship is docked in Juneau on Aug. 25, 2021. (Michael Lockett / Juneau Empire File)
Ships in Port for the week of June 19

Here’s what to expect this week.

Mark Sabbatini / Juneau Empire 
Peter Froehlich, a retired Juneau district judge who is now a volunteer tour guide, explains the history of the history of the Kimball Theatre Pipe Organ in the State Office Building to a group of visitors Thursday. The organ has been idle since 2020 due to the COVID-19 pandemic, and now needs repairs before regular Friday lunchtime concerts and other performances on the 94-year-old instrument can resume.
Historic organ is in need of tuneup

How much it will cost and who will do it remain up in the air.

Candidate for Alaska’s lone seat in the U.S. House of Representatives Tara Sweeney, a Republican, was in Juneau on Monday, May 16, 2022, and sat down with the Empire for an interview. A lawsuit filed Thursday challenges a decision to omit Sweeney from ballots in the upcoming Aug. 16 special election. (Peter Segall / Juneau Empire File)
Lawsuit says Sweeney should advance in House race

The lawsuit says the Division of Elections misinterpreted state law.

Most Read