Zecharia Sitchin was an author of a number of books proposing an explanation for human origins involving ancient astronauts. Sitchin attributed the creation of the ancient Sumerian culture to the Anunnaki, which he stated was a race of extraterrestrials from a planet beyond Neptune called Nibiru. He asserted that Sumerian mythology suggests that this hypothetical planet of Nibiru is in an elongated, 3,600-year-long elliptical orbit around the Sun. Sitchin's books have sold millions of copies worldwide and have been translated into more than 25 languages.