Word order in 銀河鉄道の夜

Question

I was reading 銀河鉄道の夜, and I’m confused on the choice of word order in the following sentence. I understand what the sentence means, but I do not understand why みんな isnt before が.

たしかにあれがみんな星だと

Let me know if more context is necessary.

Answer 1

For clarity, in the context of the 銀河鉄道の夜 the clause the question is about is meant as an answer to

[...]このぼんやりと白いものがほんとうは何かご承知ですか。

— something the teacher asks the class while pointing to an illustration of the Milky Way, and it is part of a longer sentence that continues on like so:

たしかにあれがみんな星だと、いつか雑誌で読んだのでしたが...

With that out of the way, the reason みんな comes after が here is because it is used as an adverb (meaning "all, everything, wholly") rather than a noun.

たしかにあれがみんな星だと　...that (it is/they are) certainly all stars

みんな as a noun could not really have been used here, as would then refer to a group of people, while the sentence is about what the Milky Way is composed of.

This use corresponds to its second definition on jisho.org as well as on goo.ne.jp (here listed under みな). Those two sites also give the following examples, respectively:

木の葉はみんな落ちてしまった。The leaves have all fallen.
今回の不始末はみんな私の責任です　This (case of) mismanagement is entirely my fault. (emphasis, second translation mine)

As adverbs cannot take the subject-marker が, the only way for this みんな to end up before it would be by being placed before あれが, but while (as neither a native speaker nor an advanced learner) I may be wrong on this and cannot properly explain it, to me it sounds incredibly weird and is most likely just incorrect.