Another piece of settled science bashing from the baneful keyboard of Tim Cullen at https://malagabay.wordpress.com/2015/03/29/the-society-for-the-detection… … the missing world, in this instance, being an object between Mars and Jupiter, marked by the asteroid belt. Way back, once upon a time, it was thought a planet had existed in this part of space and the asteroids are remnants of said planet. Some people, even now, are prepared to consider this a possibility. However, by the time the 19th century came the idea of a planet being cracked upon was deemed a step too far as uniformitarianism had come into play, and catastrophism could not be allowed to blossom. It had to be quenched – everywhere it reared its unwanted head. The term squashed might be more apt – but you get the general idea. Any hint of catastrophism in the history of the solar system had to be suppressed – and this may be why Velikovsky suffered such vitriolic attacks from an establishment that felt threatened by the populism that seemed to be generated by the big sales of his books, Worlds in Collision and Earth in Upheaval (but this was in the 1950s, long after the debate had died down). At the same time, mainstream could not imagine any process powerful enough to shatter a planet.
Another problem, raised by the astronomer Encke and others of his ilk, said that if a planet had broken apart the new orbits of the fragments must pass through the point where the explosion occurred (assuming an explosion caused the fragmentation). They found no such point common to the orbits of the four large asteroids (which includes Ceres and Vesta). However, Cullen points out that the comet family of Jupiter has a distinct common point through which many of them pass as they orbit the Sun (see also https://malagabay.wordpress.com/2013/04/25/the-other-big-bang-theory/)