Scientists have discovered a potential dwarf planet, 2017 OF201, inhabiting the outer reaches of our solar system. The object is about 435 miles (700 km) wide and takes roughly 25,000 years to orbit the sun. Located at a distance of 90.5 astronomical units from the sun, it’s one of the most distant visible objects in the solar system.
Led by astrophysicist Sihao Cheng, researchers identified the object using telescopes in Chile and Hawaii over a seven-year period. The discovery has sparked interest in the possibility of other similar objects existing beyond 150 astronomical units from the sun. These objects are too far away to be detectable currently.
The object’s size is estimated to be smaller than Ceres, but larger than Pluto. Its mass is about 20,000 times smaller than Earth’s and 50 times smaller than Pluto’s. The composition of 2017 OF201 is unknown, but likely similar to other icy bodies.
Cheng noted that the discovery has implications for hypotheses involving the potential existence of a ninth planet in our solar system, dubbed Planet X or Planet Nine. The object’s unusual orbit does not follow the pattern exhibited by other known trans-Neptunian objects, which tend to cluster together. This challenges the hypothesis that such clustering is caused by the gravity of a yet-to-be discovered planet.
The International Astronomical Union defines a dwarf planet as an object that orbits the sun and is mostly round but has not cleared its orbit of other objects. The discovery of 2017 OF201 will be scrutinized in upcoming studies, with Cheng’s team contributing to its open-access research site arXiv.
Source: https://www.reuters.com/science/possible-new-dwarf-planet-spotted-near-edge-solar-system-2025-05-30