Where does “天の川銀河” come from?

天の川銀河 (Japanese) comes from Japanese 天の川, from Japanese 天, from Old Japanese 天, from Proto-Japonic *amay.

Ancestry of “天の川銀河”, step by step

天の川銀河 traces back through two separate lines of ancestry.

via Japanese 天の川

StepLanguageWordMeaning
1Japanese天の川Milky Way
2Japanese天the sky, the heavens; the area above a kitchen...
3Old Japanese天sky, heavens
4Proto-Japonic*amay—

via Japanese 銀河

StepLanguageWordMeaning
1Japanese銀河galaxy
Every word from Proto-Japonic *amay →Every word from Old Japanese 天 →Every word from Japanese 天 →