Nibiru (also transliterated Neberu, Nebiru) is a term in the Akkadian language, translating to "crossing" or "point of transition", especially of rivers,Akkadian Dictionary: nēbertu *, nēburu in Akkadian Dictionary i.e., river crossings or ferry-boats. While the nature of the "crossing" in astronomy has "long been a source of confusion in scholarly and popular opinion", in a 2015 report for the Cuneiform Digital Library Bulletin,Freedman, Immanuel "The Marduk Star Nēbiru". Retrieved 2015-10-11 (Cuneiform Digital Library Bulletin 2015:3) Immanuel Freedman analyzed the extant cuneiform evidence and concluded that the hypothesis that the name Nēbiru may be assigned to any visible astronomical object that marks an equinox is supported by cuneiform evidence.
Role in Babylonian cosmology Nibiru was considered the seat of the summus deus who shepherds the stars like sheep, in Babylon identified with Marduk. The establishment of the nibiru point is described in tablet 5 of the creation epic Enûma Eliš: “When Marduk fixed the locations (manzazu) of Nibiru, Enlil and Ea in the sky". Ernst Weidner in: Reallexikon der Assyriologie, vol. 2, de Gruyter, Berlin 1978, p. 381 The Enûma Eliš states:
Nibiru is described more closely on a complete cuneiform tablet:Translated from the German translation of Wolfram von Soden in: Zeitschrift für Assyriologie (ZA), no. 47, p. 17.
Böhl calls the text "objectively the most difficult passage, although it has been handed down in its entirety. The Nibiru tablet does not provide any essential help for the clarification." F.M.T. Böhl in: Die 50 Namen des Marduk, Archiv für Orientforschung (AfO) no. 11, 1936, p. 210.
In the enumerations, Nibiru is mentioned at different astronomical locations in conjunction with the positions of stars and planets, mostly as the "star of Marduk", however, the various stars or planets were not subject to any fixed interpretation. For example, the "star of Ea" was described at various "revelation spots" including Vela, Fomalhaut, and Venus. Similar interpretations were made for the other "stars of the gods", so multiple celestial coordinates must be considered. Nibiru has been associated with the area of Libra. The Nibiru constellation rose in the month of Tišritum, around autumnal equinox. However Nibiru was also a name for the planet Jupiter (Volume 11, N, part 2 / page 145 / 34MB PDF) when observed in the month of Tišritum. In the MUL.APIN, Nibiru is identified as Jupiter:
Conversely, Tablets K.6174:9’ and K.12769:6’ refer to it as Mercury: "If Mercury (MULUDU.IDIM.GU4) divides the sky and stands there, [its name] is Nibiru."
References
Literature A. Schott, Marduk und sein Stern, Zeitschrift für Assyriologie 43 (1936), 124-145. Johannes Koch, Der Mardukstern Neberu, Die Welt des Orients 22 (1991), 48-72.