An astronomer finds a very old astronomy book, in which the Messier object M31 is referred to as the Andromeda Nebula. The astronomer might suspect that this book was written BEFORE

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The term "Andromeda Nebula" was commonly used before Edwin Hubble demonstrated in 1924 that the Andromeda Nebula (M31) was actually a galaxy outside the Milky Way, leading to a shift in terminology from "nebula" to "galaxy" for such objects.

An Astronomer Finds a Very Old Astronomy Book, in Which