July 18: Comets! Comets! Comets!

Between July 16 and 22, 1994, the comet Shoemaker-Levy 9 broke up in the tidal forces of Jupiter's gravitational field, making a series of spectacular splashdowns into the planet's viscous atmosphere. (The comet didn't break up entirely, however, and its main body continues to orbit Jupiter today.)

F.M. Riley, the Missouri pastor of a group named the Last Call - also author of 1994: The Year of Destiny - claimed the Shoemaker-Levy 9 incident proved his prophecy that Earth too was about to be struck by a comet. In the time since, as such an event has continued not to occur, Riley has shifted his claims away from Shoemaker-Levy 9 and attached them to the concept of a "Planet X", or Nemesis, or "Niburu". This is a hypothesized dark body circulating in the outer solar system which will soon enter a tighter orbit and wreak catastrophe on Earth.

These fringe ideas about Planet X have antecedents in theories circulated in the 1950s by the psychiatrist Immanuel Velikovsky. Velikovsky's book Worlds in Collision attempted to explain several episodes from the Bible using astronomical hypotheses. For instance, a comet which Velikovsky claimed spontaneously sprang from Jupiter (later becoming the planet Venus) was considered the cause of the plagues of Exodus. Other comets and passing bodies caused the flood of Genesis, the fall of the tower of Babel, and the one-hour cessation of the Earth's rotation described in the book of Joshua.

Needless to say, these claims are absurd.