Planet Nine Back in Play as Scientists Spot Mysterious Object Beyond Pluto

A recent study has identified a potential candidate for the hypothesized Planet Nine, a massive celestial body believed to exist in the distant reaches of our solar system. The research, led by Terry Long Phan and colleagues, utilized data from two far-infrared all-sky surveys—NASA’s Infrared Astronomical Satellite (IRAS) from 1983 and Japan’s AKARI satellite from 2006—to search for slow-moving objects beyond Neptune.

Infrared Surveys Reveal a Slow-Moving Object

By comparing the IRAS and AKARI datasets, separated by 23 years, the team aimed to detect objects exhibiting minimal movement over time, indicative of distant planetary bodies. They focused on identifying sources with angular separations between 42 and 69.6 arcminutes, corresponding to objects located approximately 500 to 700 astronomical units (AU) from the Sun. This range aligns with theoretical predictions for Planet Nine’s distance and mass, estimated between 7 and 17 times that of Earth .

The researchers initially identified 13 candidate pairs showing the expected motion. After thorough analysis, including visual inspection of the infrared images, one candidate stood out. This object was detected in the IRAS data but not in the corresponding AKARI position 23 years later, and vice versa, suggesting it had moved slowly across the sky during that period.

Characteristics Consistent with Planet Nine Hypotheses

The infrared signature of the candidate, particularly at wavelengths of 65 and 90 microns, indicates a temperature between 28 and 53 Kelvin. Such thermal characteristics are consistent with models of a distant ice giant similar to Uranus or Neptune but situated far beyond Pluto’s orbit . The object’s estimated mass and distance further support its candidacy as Planet Nine.

To ensure the reliability of their findings, the team accounted for potential background noise and artifacts. They excluded sources within ten degrees of the galactic plane and twenty degrees of the galactic center due to high contamination risks from infrared cirrus and dense star fields. Flux consistency tests eliminated any detections that did not match the expected emission levels for a cold planet, and visual inspection of the raw sky maps ruled out spurious detections or scan-induced anomalies .

Next Steps in Confirming the Discovery

While the findings are promising, the researchers emphasize that additional observations are necessary to confirm the object’s nature and determine its precise orbit. They suggest follow-up studies using instruments capable of detecting faint, slow-moving objects, such as the Dark Energy Camera (DECam), which can observe such targets within an hour of exposure .

The identification of this candidate marks a significant step in the ongoing search for Planet Nine, a quest that began in earnest in 2016 when astronomers observed unusual clustering in the orbits of trans-Neptunian objects. If confirmed, this discovery would not only validate years of theoretical work but also enhance our understanding of the solar system’s structure and formation.