"galactic halo." YourDictionary, n.d. Web. 18 December 2018. <https://www.yourdictionary.com/galactic-halo>.
galactic halo. (n.d.). Retrieved December 18th, 2018, from https://www.yourdictionary.com/galactic-halo
A large, spherical region of relatively dust-free space surrounding a spiral galaxy such as the Milky Way. The inner regions of the galactic halo contain globular clusters of very old stars, while the outer regions are apparently occupied by large amounts of dark matter.