Space rock is a subgenre of rock music. The term originally referred to a group of early mostly British 1970s progressive rock and psychedelic bands such as Hawkwind and Pink Floyd. The music is characterised by slow, lengthy instrumental passages dominated by synthesisers, experimental guitar work and science fiction lyrical themes. Later the words were changed to mean a series of late 1980s British alternative rock bands that drew from earlier influences to create a more melodic but still ambient form of pop music.