Being spiral in shape, our Galaxy is already in permanent rotational motion.
But astronomers have found that the Milky Way also moves perpendicular to the Galactic plane. This creates small wobbling movements and a chaotic wave pattern, much like a huge flag fluttering in the wind.
Observing the stars located 6,500 light years above and below the Sun, as well as inwards and outwards from the Galactic centre, astronomers noted that their upwards and downwards velocities show a wave-like behaviour.
Although the source of the forces is not yet understood, possible causes include spiral arms stirring things up or ripples caused by the passage of a smaller galaxy through our own.Read more at Leibniz Institute for Astrophysics Potsdam