A new study rekindles hope of locating the enigmatic celestial body that could complete the solar system.
Ever since Pluto lost its title as the ninth planet in 2006, astronomers have been searching for a worthy successor. The idea of a “Planet Nine” officially emerged in 2016, when scientists Konstantin Batygin and Mike Brown suggested that the unusual orbits of several trans-Neptunian objects — bodies beyond Neptune — could be caused by a large, distant, yet unseen planet orbiting the edge of the solar system.
Now, that search has just taken a significant leap forward.
A study led by Terry Long Phan and made available on the scientific repository arXiv may have revealed the first real clue to the existence of such a planet. Using data from two far-infrared surveys conducted 23 years apart — IRAS (1983) and AKARI (2006) — the team compared thousands of slow-moving light sources in the sky. The goal was to find something that behaved like a distant, massive planet, with an orbit so long that it would take thousands of years to complete one full orbit around the Sun.
After rigorous filtering and visual inspection, astronomers identified a pair of sources with characteristics consistent with what is expected of Planet Nine: slow motion, correct position, and lack of detection in the same region of the sky at both times. This suggests a real object moving between 500 and 700 astronomical units (AU) from the Sun — that is, 500 to 700 times the distance from Earth to the Sun — with a mass between 7 and 17 times that of Earth.
Despite the enthusiasm, the researchers themselves acknowledge that the current data is not sufficient to confirm whether the object is really Planet Nine. New observations, especially with more powerful instruments such as the DECam camera in Chile, will be essential to map its orbit and prove its existence.
If confirmed, Planet Nine would not only change the course of school textbooks, but it would also open a new window into our understanding of the formation and structure of the solar system. Science doesn’t have all the answers yet — but it’s getting closer to figuring out whether we’re really “missing” a giant planet lurking in the darkness of space.
About the image:
Artist's impression of the proposed Planet Nine in distant orbit around the sun.
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