In addition to the inner, visible portion of the halo, there is the much larger region known as the '''dark halo''' or '''extended halo'''. This region is believed to hold a large amount of [[dark matter]], the presence of which can only be inferred through its gravitational influence in the rotation of the galaxy.<ref>http://www.daviddarling.info/encyclopedia/G/galhalo.html</ref> | In addition to the inner, visible portion of the halo, there is the much larger region known as the '''dark halo''' or '''extended halo'''. This region is believed to hold a large amount of [[dark matter]], the presence of which can only be inferred through its gravitational influence in the rotation of the galaxy.<ref>http://www.daviddarling.info/encyclopedia/G/galhalo.html</ref> |