銀河 ぎんが系内 けいない星雲 せいうんだったら
gingakei nai seiundattara

Noun
Da Copula

The "-tara" conditional form ("if/when…") of 銀河系内星雲

1. If it were a nebula within the Milky Way…; If it’s a nebula within the Milky Way…

Tara Conditional
Astronomy