"Gravastar" / "Celebrity Science" is a single, in support of Hybrid's then upcoming second album Morning Sci-Fi. "Gravastar" / "Celebrity Science" was given a limited release, and is therefore rare. "Celebrity Science" is not included in Morning Sci-Fi or any Hybrid album for that matter, but was featured (along with "Gravastar") in an edited form as part of the in-game soundtrack to the PC game F1 Challenge '99-'02, which was released in 2003. "Gravastar", on this single, is longer than on Morning Sci-Fi. The single was later released on iTunes on June 26, 2008.