Hemispheres is the sixth studio album by Canadian rock band Rush, released on October 24, 1978, by Anthem Records. It reached No. 14 in Canada and the UK, and No. 47 in the US. The album was a steady seller in the group's catalogue, and was certified platinum by the Recording Industry Association of America for selling one million copies 15 years later.

After a particularly exhausting tour supporting A Farewell to Kings to capitalise on their growing fanbase, Rush had a dedicated rest period. They returned to Rockfield Studios in Wales to record a follow-up album but had no preconceived ideas, and spent two weeks writing and arranging new material with some difficulty over its direction. It is the final Rush album to feature a side-long track; the 18-minute opener "Cygnus X-1 Book II: Hemispheres" concludes the story initially left as a cliffhanger on A Farewell to Kings, and the Apollonian and Dionysian concept addressed in drummer Neil Peart's lyrics are represented on the cover artwork. The final track, "La Villa Strangiato", was the band's first instrumental.

Hemispheres received a mostly positive reception from critics upon release, and has gained further acclaim retrospectively. It was the first Rush album to receive widespread FM radio airplay, helped by the release of "Circumstances" and "The Trees", the two shorter tracks on the album, as singles. The album has been remastered several times, and a deluxe 40th anniversary edition with previously unreleased live tracks followed in 2018.