I've sung this song at the pub! It's about relativity, as you might expect from astrophysicist Brian May. Explorers set off to find a new planet to live on, but when they come back much more time as passed on Earth as they were travelling so fast and their loved ones have died.

Always one of my favourite Queen songs, but some people don't even realise it's on the same album as Bohemian Rhapsody.