What exactly was Planet X?
Once upon a time, the number of observed planets were limited to the “naked eye” ones. Mercury, Venus, Earth, Mars, Jupiter, and Saturn. Knowing Kepler’s Laws of orbital motion, and more importantly, Newton’s Laws of Gravity, something was peculiar about Saturn’s orbit. It wasn’t behaving as it should. It was speculated, that a massive planet, dubbed “Plnaet X”, beyond Saturn, might exist, creating gravitational perturbances in its orbit. The discovery of Uranus proved this speculation correct. Even more interesting, Uranus appeared to be perturbed as well. Using mathematical equations to calculate the disturbances of Uranus, the planet Nertune was dis covered, within 1 degree of where it was predicted to be… on the very first night of searching. Uranus and Neptune were still not behaving right. It took a longer exercise, mostly of looking at photographic plates of the sky to discover the next “Planet X” which was named Pluto. This accounted for most of the observed irregularities in
