Astronomy is where the phrase "dog days of summer" originated.
This expression wasn't influenced by drowsy, hot puppies. According to National Geographic, the "dog" in question is Sirius, the Dog Star, which emerges in the sky in late July as a member of the Greater Dog constellation. The term "dog days" was used by the Greeks and Romans to describe the hottest part of the year, which was also thought to bring catastrophes like fever.
Did you Know? There is a very strange reason why Captain America isn't eating in a post credit scene of The Avengers.