One fleeting glimpse beyond Pluto hints at a hidden outer-solar-system population
Astronomers identified 2017 OF201, a ~700-km dwarf-planet candidate in a 24,000–25,000-year orbit, currently about 90 AU from the Sun with a perihelion near 45 AU and an aphelion near 1,600 AU. It was discovered by linking faint archival observations across two decades, meaning it is visible for only about 0.5% of its orbit. This narrow window implies there could be hundreds more similar bodies hidden in the outer solar system, highlighting census biases that only count objects bright near perihelion. While 2017 OF201 is not proof of Planet Nine, the work constrains models and shows how archival data can reveal distant worlds long after observations were made. The object's size is inferred from brightness assuming an albedo and may be rounded; its exact shape awaits future data.