The phrase “the dog days of summer” doesn’t refer to an actual dog. To astronomists in ancient Greece and Rome, the constellation Canis Major  (“the greater dog,” in Latin) showed a hound chasing the constellation Lepus, a hare. The star representing the dog’s nose is Sirius. Early astronomers noted that Sirius seemed to rise just before the sun during the hottest weeks of the year—late July to August. In this way, Sirius was associated with a season that could bring fever or catastrophe. Those calamitous days came to be known as “the dog days of summer.”