the 19th century Ancient Greece, The Greek philosopher Aristotle thought that comets were dry exhalations of Earth that caught fire high in the atmosphere or similar exhalations of the planets and stars. However, the Roman philosopher Seneca thought that comets were like the planets, though in much larger orbits. He wrote:The man will come one day who will explain in what regions the comets move, why they diverge so much from the other stars, what is their size and their nature.