The warp in the Milky Way's spiral disk is precessing backward under the influence of the enormous mass of dark matter that forms an invisible halo around our galaxy, Chinese astronomers have discovered.
About one-third of all spiral galaxies have a distinct warp to their disk-shaped structure, like a vinyl record that has been bent. It's usually the result of a variety of factors; a collision with another galaxy in the past is believed to be the primary culprit in causing the Milky Way's warp in the first place, but further interactions with satellite galaxies and the intergalactic magnetic field, as well as the infall of vast clouds of gas, can also play their part. However, in the case of the Milky Way at least, the major player in maintaining the warp is the dark matter halo that surrounds the disk and exerts a torque on it.
