Translating "Nocte volat caelī mediō"

Question

Line 184 of Vergil's Aeneid, Book IV, begins as follows:

Nocte volat caelī mediō

Would this be translated as "She of the sky flies in the middle of the night", or "At night she flies in the middle of the sky"? I remember learning that "medius, media, medium" is an agreeing adjective meaning "middle of" which does not take the genitive. However, the latter translation I came up with seems to flow better.
Additionally, are there any other ways to distinguish nouns in the same case when there are such ambiguities?

Answer 1

As an adjective, indeed, medius, -a, -um does not take a genitive. However, there is a noun, the substantive medium, -i, which also means "middle" or "midst." Referring to a physical space, it's fairly common during the Augustan era and later, and, yes, it can take a genitive. Compare this passage of Livy 37.13.10:

insidiis medio ferme viae positis

with traps laid closely in the middle of the road

So your second translation is closer, but it's still not quite there. It would help to look at the next word: terraeque. The medio here isn't what we think of as "the middle of the sky," but rather the space between "heaven" and earth (i.e. aer/ἀήρ).

So an even more literal translation would be:

She flies by night between heaven and earth

Yet still this isn't the best translation, because it's not our idiom, but at least it gets across what the grammar and words are doing in the passage.