Planet nine mystery deepens as new discovery challenges hidden planet theory
Key takeaways
- Is there a massive undiscovered planet on the outer reaches of the Solar System?
- Their theory relates to the Kuiper Belt, a giant belt of dwarf planets, asteroids and other matter that lies beyond Neptune (and includes Pluto).
- This would be comparable to what happens with our own Moon.
Why this matters: new research or scientific developments with potential real-world impact.
Is there a massive undiscovered planet on the outer reaches of the Solar System? The idea has been around since before the discovery of Pluto in the 1930s. Labelled as planet X, prominent astronomers had put it forward as an explanation for Uranus s orbit, which drifts from the path of orbital motion that physics would expect it to follow. The gravitational pull of an undiscovered planet, several times larger than Earth, was seen as a possible reason for the discrepancy.
That mystery was ultimately explained by a recalculation of Neptune s mass in the 1990s, but then a new theory of a potential planet nine was put forward in 2016 by astronomers Konstantin Batygin and Mike Brown at Caltech (the California Institute of Technology).
Their theory relates to the Kuiper Belt, a giant belt of dwarf planets, asteroids and other matter that lies beyond Neptune (and includes Pluto). Many Kuiper Belt objects – also referred to as trans-Neptunian objects – have been discovered orbiting the Sun, but like Uranus they don t do so in a continuous expected direction. Batygin and Brown argued that something with a large gravitational pull must be affecting their orbit, and proposed planet nine as a potential explanation.