Planet X, often called Nibiru. This rogue planet supposedly passes through the inner solar system once every few thousand years. People have claimed that each time Nibiru does this, it causes great calamity on the earth and on other planets. Some people have linked these past catastrophes to biblical events, such as the Flood. It is very tempting for many Christians to link predicted return visits of Nibiru to the inner solar system with end-time prophecies, such as Wormwood in Revelation 8:10–11.
The word Nibiru comes from the ancient Akkadian language, meaning crossing, such as in fording a river. It also has the connotation of a transition point. It was with this meaning that Nibiru came to be used in Babylonian astronomy to refer to an equinox. But it can have other meanings, such as a reference to the constellation Libra, which was the location of the autumnal equinox in the first millennium BC. Nibiru also can refer to locations in the sky in conjunction with certain stars or planets. Nibiru is associated with the Babylonian god Marduk, which in turn is identified with the planet Jupiter.