ᚾᚢᚱᚦᚱᛚᛁᚢᛋ nurþrlius

Norðrljós: the northern lights in the King's Mirror

The only medieval Norse account of the aurora is in a Norwegian textbook of about 1250, and it offers three natural explanations, not a myth.

Norðrljós described in the King's Mirror: Medieval source Aurora as the Valkyries' armour: Modern guess

What the sources say

The passage is in chapter 19 of the King's Mirror. We paraphrase it below; the Old Norse text is medieval, and Laurence M. Larson's English translation (The King's Mirror, 1917) is in the public domain.

The names

ᚾᚢᚱᚦᚱᛚᛁᚢᛋNorðrljós: 'north light', the aurora
ᚴᚢᚾᚢᚾᚴᛋ ᛋᚴᚢᚴᛋᛁᛅKonungs skuggsjá: 'the king's mirror', a Norwegian book of instruction, c. 1250

Runes: our letter-by-letter spelling in the Viking-age Younger Futhark; these names come down to us in manuscripts written in the Latin alphabet. How we write runes.

The story and what it means

Konungs skuggsjá, the King's Mirror, is a Norwegian book of about 1250 in which a father teaches his son about trade, the court and the world. Writing about Greenland, the father describes what the Greenlanders call the northern lights, norðrljós: a light that is brighter the darker the night, never seen by day, like a great flame seen from far off, with sharp points shooting up into the sky, always moving, sometimes bright enough to travel and hunt by.

He then weighs three explanations: that a fire surrounds the ocean at the edge of the world; that sunlight reaches up from below the horizon, because Greenland lies at the edge of the earth; or that the ice and frost there are so strong that they give off light. He finds the third most likely. It is a remarkable passage: a careful observer reasoning about nature, not telling a myth.

You will often read that the Vikings saw the aurora as light reflected from the Valkyries' armour. No Old Norse text says so. The earliest version we have found is in Thomas Bulfinch's The Age of Fable, published in Boston in 1855.

The real cause is the solar wind: particles from the Sun, steered by Earth's magnetic field, strike the upper atmosphere 100 to 300 km up around the magnetic poles and make oxygen and nitrogen glow green, red and violet. The aurora is commonest in a ring about 20° from the magnetic pole, which runs over northern Norway, Iceland and southern Greenland.

How sure are we?

Claim	Grade	Basis
Norðrljós described in the King's Mirror	Medieval source	Konungs skuggsjá, Norway, c. 1250, ch. 19.
Aurora as the Valkyries' armour	Modern guess	Not in any Old Norse source; earliest found in Bulfinch (1855).

In tonight's sky

City	Latitude	Dark hours tonight	Moon
Reykjavík	64.1°N	13 h 40 min (Sun 6° or more below the horizon)	99%
Oslo	59.9°N	13 h 20 min (Sun 6° or more below the horizon)	99%
Stockholm	59.3°N	13 h 20 min (Sun 6° or more below the horizon)	99%
London	51.5°N	12 h 55 min (Sun 6° or more below the horizon)	99%
New York	40.7°N	12 h 25 min (Sun 6° or more below the horizon)	98%
Sydney	33.9°S	9 h 50 min (Sun 6° or more below the horizon)	100%

We do not forecast aurora; it depends on solar activity that changes by the hour. What we can tell you is how long and how dark tonight is.

Sources

Texts: Konungs skuggsjá ch. 19. Quotations from the public-domain translations of the Poetic Edda by Henry Adams Bellows (1923) and the Prose Edda by Arthur Gilchrist Brodeur (1916); Brodeur's chapter numbers. Konungs skuggsjá ch. 19 (English tr. L. M. Larson, The King's Mirror, 1917); Cleasby-Vigfusson s.v. norðr-ljós; T. Bulfinch, The Age of Fable (1855), ch. 38.