Why don't the relative positions of stars and other objects in a galaxy change over the year?

Question

Though the identifiable stars in a constellation (say Andromeda) and a galaxy (say the Andromeda galaxy) are situated light years apart, why doesn't the galaxy appear at different positions with respect to the stars at different times of the year?

Answer 1

First, the stars of the constellation are a couple of million light years from the Andromeda galaxy. Secondly, even the closest stars in the constellation are many light years from us. If you looked in that direction six months apart, you would be observing from opposite sides of the Earth's orbit, which is two astronomical units (AU) wide. Each light year is 126,144 AU. Compared to even one light year, the width of our observing baseline of 2 AU is insignificant. So the apparent shift in positions of the stars would also be insignificant and probably undetectable!