Copernicus was Emmett Brown's dog in 1955 named for famed scientist Nicholas Copernicus. Sometime between then and 1985, most likely by 1970, Copernicus died and was replaced by Doc's new companion Einstein, continuing with the theme of pets named after famous scientists.
Copernicus appears to be either a mixed-breed or a breed of terrier.
While Copernicus was never addressed by name in Part I, his name was mentioned in the novelization. It wasn't until Part III that his name was actually spoken and confirmed as Copernicus.
Behind the scenes
- As with Einstein in Part III, Copernicus was portrayed by a different dog than the one which was used in Part I.