What Is the Classical Origin of the Aurora Borealis?

Apollo and Aurora (1671) by Gérard de Lairesse. Wiki Commons, Public Domain

In 1619, the astronomer Galileo Galilei coined the term “Aurora Borealis” for a phenomenon observed mostly at very high latitudes: shimmering bands of color arcing across the night sky. Aurora was the name for the goddess of the dawn according to the Romans (known as Eos and usually described as "rosy-fingered" by the Greeks), while Boreas was the god of the north wind.

Although the name reflects Galileo’s Italian worldview, the lights are mentioned in various cultures.

It’s also possible that some “impressionistic” cave drawings actually depict auroras in the sky. The indigenous peoples of America and Canada also have traditions related to the auroras, and in Europe, the Norse god of winter, Ullr produced the Aurora Borealis, according to the regional mythology, to illuminate the longest nights of the year. The earliest recorded detail is from China, in 2600 B.C.

Scientific Explanation

These poetic descriptions of the phenomenon belie the astrophysical origin of the aurora borealis (and its southern twin, the aurora australis. They are the closest and most dramatic example of space phenomena.  Particles from the sun, which may emerge in a steady stream called the solar wind or in giant eruptions known as coronal mass ejections, interact with magnetic fields in the upper atmosphere of Earth. These interactions cause oxygen and nitrogen molecules to release photons of light.