The Original Planet X
Percival Lowell, a prominent astronomer, theorized a Planet X was needed to explain wobbles in the orbits of Uranus and Neptune. He predicted its location and began a search, which ultimately led to the discovery of Pluto in 1930 by Clyde Tombaugh. However, Pluto was much too small to be the Planet X Lowell envisioned.
The Search Continues: Planet Nine
Following the discovery of Neptune, astronomers again began to suspect the existence of a large, unseen planet due to subtle grouping of icy objects in the Kuiper Belt beyond Neptune. This hypothetical planet is now often called Planet Nine.
The Evidence for Planet Nine
The existence of Planet Nine is based on indirect evidence. Computer simulations suggest a massive planet, perhaps ten times the Earth's mass and similar in size to Uranus or Neptune, could explain the unusual clustering of Kuiper Belt objects. Its predicted orbit is far beyond Neptune, taking between 10,000 and 20,000 years to circle the Sun.
Is Planet Nine Real?
The search for Planet Nine is ongoing, but there is no definitive proof of its existence. The faintness and extreme distance make direct observation difficult. While some astronomers believe Planet Nine is a strong possibility, others remain skeptical.
Further Exploration
New telescopes and ongoing sky surveys may hold the key to finding Planet Nine, if it exists. The possibility of a new planet in our solar system continues to be a fascinating area of astronomical exploration.