Catasterism in myth is an ancient tradition, and the famous Greek Eratosthenes is believed to be associated with this practice of putting gods and heroes in the stars. It’s been more difficult to make specific attributions of stories with specific constellations in the Germanic myths. There are fewer extant stories to begin with, and the ones we do have rarely make reference to the stars. And while we know the Vikings and their forebears were great shipbuilders and navigators, no star charts or other handy guides have allowed us a window into just how much northern Europeans shared their cousins’ taste for naming the heavens after their heroes.
There are a couple of exceptions; here’s one. In Snorri Sturluson’s story of Thor’s battle with Hrungnir in the Prose Edda, Thor explains how he managed to create one particular star as he is going to have a chunk of whetstone dislodged from his forehead. His nurse finds the story so enthralling she fails to produce the magic necessary, and the stone stays stuck in his head forever. Here’s the story:
Then came the wise woman who was called Gróa, wife of Aurvandill the Valiant: she sang her spells over Thor until the hone was loosened. But when Thor knew that, and thought that there was hope that the hone might be removed, he desired to reward Gróa for her leech-craft and make her glad, and told her these things: that he had waded from the north over Icy Stream and had borne Aurvandill in a basket on his back from the north out of Jötunheim. And he added for a token, that one of Aurvandill’s toes had stuck out of the basket, and became frozen; wherefore Thor broke it off and cast it up into the heavens, and made thereof the star called Aurvandill’s Toe. Thor said that it would not be long ere Aurvandill came home: but Gróa was so rejoiced that she forgot her incantations, and the hone was not loosened, and stands yet in Thor’s head. Therefore it is forbidden to cast a hone across the floor, for then the hone is stirred in Thor’s head.
Note that “hone” is a noun version of “to hone” a knife or sword, as in a stone used to accomplish that honing.
The question then is, if this is our most obvious catasterism, what star do we associate with Aurvandil’s toe?
The etymology of “Aurvandil”, according to scholar Rudolf Simek, puts the word alongside the Old English “Earendel”, which means “brilliance, morning star.” So we have associations with a bright star, possibly in the morning.
Typically, when we speak of a morning star, we’re referring either to the planet Venus or the brightest star in the night sky, Sirius, both of which are prominent at daybreak. A suggestion that the “Aurr” part of the word means “dawn, ray of light” certainly keeps with the early day, bright object part of the story. Also, since Thor mentions that this is something he did while coming back to Asgard, a kind of prior engagement, all of these things fit the myth.
Another possibility might be that Aurvandil’s toe is associated with the star Capella in the constellation Auriga. This more recent consideration is here argued as a consideration of Capella’s proximity to other notable mythological figures in the sky, including Hrungnir, Mokkurkalfi, and Thor’s hammer Mjolnir. The etymological evidence here isn’t bad, either. While Capella isn’t prominently associated with the morning, it is very bright, and in fact is the brightest star with a spectral signal similar to Sol, our sun. It may have been bright enough to warrant getting a mythological shout-out.
I’m inclined to believe the fact that Aurvandil’s toe was frozen before Thor threw it into the stars wins the argument for Sirius – Venus, in addition to having a changing position because of its status as a planet (I don’t expect ancient sky-watchers would necessarily have thought of them as planets, but these moving figures would certainly have been worth notice), is also noticeably different from other stars because of the way it reflects light. Since Capella is also a more yellowish color, it seems like Sirius, a brighter, bluer color in the night sky, would look more like a frozen giant’s toe, I think it’s probably Aurvandil’s toe.
But since we don’t have solid records on any of this, my speculation doesn’t hold up much better than anyone else’s (and less so, even), though we can hope we will eventually find evidence firmly establishing where Aurvandil’s toe ended up, or what Thjazi’s eyes look like in the sky.
In any case, the whole situation leaves us to ask further: what deeds did Aurvandil do to earn immortality in the sky? Thjazi, at least, had his daughter to bargain for a respectful remembrance, but Aurvandil’s is a story left to our imaginations.