Zecharia Sitchin interpreted in the wrong way the Sumerian epic of creation, Enuma Elish.
Marduk = Nibiru = Jupiter
Since Venus and Mercury, two of Jupiter's former satellites (now known as the Sun's chariots) also contributed to each and every major astronomical/geological cataclysm, they also bear the name Nibiru.
Nibiru is not some outer planet, slowly approaching Earth: it is already very close to us, in plain sight, once the Sun reaches the limit of its alloted space for precession, the two planets which orbit the Sun, Venus and Mercury, will be released/set free once again.