Two astronomers in Japan have recently published a study in the Astronomical Journal, uncovering possible evidence of an Earth-like planet, referred to as “Planet Nine,” in the outer solar system behind Neptune. The astronomers, Patryk Sofia Lykawka of Japan’s Kindai University and Takashi Ito of Japan’s National Astronomical Observatory, revealed that the Kuiper Belt—a doughnut-shaped ring of icy objects encircling the Sun beyond the orbit of Neptune—may contain a massive Earth-like planet.
The scientists predict that Planet Nine would have a mass between 1.5 and 3 times that of Earth and would be located at 500 astronomical units (AU) from the Sun with an orbit inclination of 30 degrees. They believe that the discovery of this planet could provide valuable insights into the fundamental properties of the Kuiper Belt, including the existence of trans-Neptunian objects (TNOs) on peculiar orbits.
In their study, the researchers suggest that a primordial planetary body could survive in the distant Kuiper Belt as a Kuiper Belt planet (KBP). They emphasize the importance of obtaining more detailed knowledge of the orbital structure in the Kuiper Belt to confirm or rule out the existence of a hypothetical planet in the outer solar system and gain insights into planet formation and dynamical evolution in the trans-Jovian region.
Astronomers have been studying the potential existence of a ninth planet since 2016, as it could explain the peculiar orbits of several Kuiper Belt Objects. Caltech researchers found evidence of a planet with a highly elongated orbit in the outer solar system, approximately 10 times the mass of Earth and orbiting about 20 times farther from the Sun on average than Neptune. It is estimated that this planet takes between 10,000 and 20,000 years to complete one orbit around the Sun. Although it has not been directly observed, its existence has been inferred through mathematical modeling and computer simulations.
Mike Brown, one of the researchers, stated that the putative ninth planet, which is 5,000 times bigger than Pluto, should be considered a true planet due to its size. He described it as a “real ninth planet” and emphasized the significance of its discovery, as only two true planets have been discovered since ancient times. The search for Planet Nine continues, exciting scientists about the possibilities that lie within our own solar system.