Smooth...
Earth That Was is a slang term for the way things were on Earth before its evacuation following the Bug Asteroid of 2198. Even six and a half decades later, many older people remember life on Earth through rose-colored glasses as a simpler time, a nostalgic fantasy of peace and prosperity. The term can be used either without irony as a wistful term of longing for the way things used to be, or dripping with bitter irony as an indictment for all oversimplistic longings for lost youth and a simpler time that really wasn't any better than the world of today.
Behind the Scenes[]
This is a reference to Firefly, where they also left Earth behind, a staple of sci-fi tropes .