As a naked-eye obsever of the cosmos, I can proudly answer that.
One. The Andromeda galaxy. If Moses could see the Pleiades, a well-known asterism in Taurus (the Bull: remember his brother Aaron make a golden calf and there's a really good astronomical/zodiacal reason for the selection but you'll have to figure that one out yourselves, hehheh), he could have most likely seen Andromeda with his naked-eye.
One. The Andromeda galaxy."
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Spotting M31 with my unaided eye is my personal measure of a night with "good seeing" worthy of dragging out the telescope.
You're right: M31 (Andromeda Galaxy) could have been seen by Moses.
But you're also wrong: he could have seen two galaxies:
Moses (like you) also certainly could have seen the Milky Way -- our own galaxy -- "from the inside looking out"...
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The point of my question was, "Even having seen those two galaxies, could he have recognized them (and written about them) for what they are: millions of stars bound into huge spiral structures by gravity (at vast distances from Earth)? No.
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The same holds true for Bishop Ussher: he had no concept of the universe as we (using tools we have made with our God-given talents) now do.
They could get by with writing, reading, and interpreting "Begats" to derive their (mis)interpretation of the age of the Universe. We have no such excuse...