Since 1906, astronomers have been searching for the existence of an elusive ninth planet in our solar system . A new study out of Princeton University scientists suggests they may be close to finding one. The study proposes that something at the edge of the solar system is tilting the orbits of icy rocks in the Kuiper Belt. That includes the dwarf planets of Pluto and Eris. To tilt the orbits of smaller objects, that thing is likely a much larger body. It's been called “Planet Y” by astronomers. The findings were published in the journal Monthly Notices of the Royal Astronomical Society: Letters. Lead author Amir Siraj said in a statement that the unseen planet would likely be "smaller than the earth and probably bigger than Mercury.” But he also warned, “This paper is not a discovery of a planet." Instead, he said, it is "the discovery of a puzzle for which a planet is a likely solution.” Planet Y is one of a few theorized planets experts say could be lurking in the Kuiper Belt. Another is Planet X. It is a proposed large planet that could be five to 10 times the mass of Earth. If it exists, it would orbit the sun every 10,000 to 20,000 years. Experts say that both planets exist. Planet X was first proposed by astronomer Percival Lowell in 1906. He spent the final years of his life searching for and never finding it. He died 14 years before Pluto was found. It served as the solar system’s ninth planet until 2006. That's when Pluto was labeled a dwarf planet instead. Siraj said if there is a ninth planet out there, the new telescope at the Vera C. Rubin Observatory will find it. It is set to begin a 10-year survey of the night sky. Reflect: How do you think curiosity about the unknown can change the way people see and explore the world around them?
