NGC 4622, which lies 111 million light-years away in the constellation Centaurus, is a spiral galaxy with a difference. It is rotating in a clockwise direction (as we see it), which means that its outer spiral arms are leading, rather than trailing, in the direction of rotation. However, a less prominent inner set of spiral arms are rotating in the normal direction of movement.
It is believed that this strange behaviour is the result of a galactic collision with a companion, which has left material orbiting the centre of the galaxy in the manner observed.
