Each ball is traveling in a straight line, but together they create an illusion that the balls are rotating jointly in a circle. Animation by brusspup.
You live in a Universe where objects far enough away are moving away faster than light speed due to expansion so you'll never get to see them. And this doesn't violate physics: stuff w/*mass* can't move faster than light, but space can expand as fast as it pleases. Enjoy your ☕