Familiar things seen at greater distances are smaller than they appear close up.
We use this simple fact to roughly estimate how far things are without actually measuring the distance by a tape measure for example. Astronomers use this method to estimate the distances to other galaxies. Objects, in this case two identical galaxies, are seen to subtend a smaller angle with increasing distance from the observer in a flat space time. An interesting consequence of curved spacetimes is the variation of angular size with distance. In a flat space objects always decrease in apparent angular size with increasing distance.