I was praying with my kid in a synagogue wherein the aron was against the eastern wall, and most of the seats were facing north or south. My kid wondered why the people around us turned to face east whenever they were standing. I had (and have) no idea. (Of course, they face east for the amida and so on. But then also for "Alenu" and shir shel yom and kadish (even those not saying it) et cetera.) Anyone know?