The galactic halo is a region surrounding a galaxy that consists of old stars, globular clusters, dark matter, and other material that extends far beyond the visible disk of the galaxy. It is typically spherical or elliptical in shape and surrounds the central bulge and disk of the galaxy. The galactic halo is thought to play a crucial role in the formation and evolution of galaxies, as well as in our understanding of dark matter and the overall structure of the universe. Scientists study the galactic halo to learn more about the history of the galaxy, the distribution of matter in the universe, and the processes that shape galaxies over time.