Astronomers have potentially identified a candidate for the elusive Planet Nine by analyzing archival infrared data from NASA's IRAS mission (1983) and Japan's AKARI satellite (2006-2007). The study, published in April 2025, highlights a faint, slow-moving object that could be the long-theorized planet lurking in the outer reaches of our solar system.
The research team, led by Terry Long Phan, focused on comparing data from the two infrared surveys, separated by 23 years, to pinpoint faint objects exhibiting the slow movement expected of a distant planet. Their analysis of AKARI's Far-Infrared Monthly Unconfirmed Source List (AKARI-MUSL) revealed a promising candidate, aligning with predicted brightness and distance parameters for Planet Nine, estimated to be between 500 and 700 AU (Astronomical Units) from the Sun, with a mass of 7 to 17 times that of Earth.
While this discovery marks a significant step, further observations are crucial to confirm the object's orbit and nature. Astronomers propose using instruments like the Dark Energy Camera (DECam) for follow-up studies. Confirming Planet Nine would revolutionize our understanding of the solar system's architecture and planetary formation models, potentially explaining the unusual clustering of trans-Neptunian objects and adding a "super-Earth" type planet, common in other star systems, to our own.