is not astrology in any meaningful sense. The sun sign is a little like trying to figure out what piece is being played in an orchestra by watching the conductor. It was done probably because it was easy, and because people somewhat worship the sun by default. This is the same, of course, as worshiping one's own ego. People like to read about themselves in a "sunny way", but they aren't so fond of a more balanced perspective. If you want to sell newspapers, then you generally want to tell people things they won't mind hearing. Hard truths sell less periodicals normally.