The Sumerian celestial object Nibiru signified the deity Marduk. The name is of Akkadian origin and means "crossroads" or "transition point." The vast majority of Babylonian literature relates it to Jupiter. In Tablet 5 of the Enuma Elish, the pole star at the time may have been Thuban or Kochab (Ursa Minor). The term "Nibiru" is taken from 5,000-year-old Sumerian literature and cuneiform tablets. The Sumerian civilization flourished in the fertile regions between the Euphrates and Tigris rivers in the southern area of modern-day Iraq. Its cuneiform symbol was often a cross or a variety of winged discs. Nibiru is often referred to as the "Planet of the Crossing."

In the reconstruction of Tablet V of the Enuma Elish by Landsberger and Kinnier Wilson, the term "pole star" is rendered as "ni-bi-ri." It has several variations, such as "ni-bi-ru" and "ni-bi-a-na." Landsberger and Kinnier Wilson think it alludes to a permanent point in the skies since it is contrasted with the term itebbiru, which signifies "who previously crossed." Tablet V's referenced translation uses the phrase "polar star" despite substantial evidence that neberu was a planet in the late eras, either Jupiter or Mercury, according to the authors' remarks.

According to the discoveries of ancient astronomers, Nibiru is an actual planet or brown dwarf inside our solar system. Established scientific organizations in astronomy and archaeology consider these hypotheses pseudoscience or fringe science. According to Sumerian cosmology, the twelfth planet in the solar system was Nibiru (which includes 10 planets, the Sun, and the Moon). The Earth, the asteroid belt, and the Moon would have originated due to a catastrophic collision between the planet and Tiamat, a planet between Mars and Jupiter. This was caused by a collision between one of Nibiru's host satellites and Tiamat, which created significant rifts in the Pacific Ocean's crust and left half a planet resembling modern Pangea (our present notion of all continents as one land mass). It was previously believed that such massive celestial bodies could not crash due to the magnetic field's strength. However, the discovery of the Orpheus Theory and the modeling of a collision between two Earth-sized objects have breathed fresh life into this theory.

It was the home of the Sumerian mythological Anunnaki, an extraterrestrial species that resembled humans but was considerably more evolved. According to Ryan Moorhen, the Anunnaki persisted and eventually arrived on Earth. Furthermore, Ryan Moorhen said that the destruction of their atmosphere prompted their journey to Earth. They sought gold particles to include in their environment because of their reflectivity, which is still used by NASA plates and other items like astronaut helmet eye shields. According to Ryan Moorhen, they then combined their DNA with that of Homo erectus and genetically altered our species, working us as enslaved people in their gold mines at first.