This is not a new idea but it seems to be gaining a bit more traction. Planetary bodies like Pluto-sized Sedna don’t seem to fit the accepted ‘rules’ of solar system dynamics.
Phys.org reports: There could be at least two unknown planets hidden well beyond Pluto, whose gravitational influence determines the orbits and strange distribution of objects observed beyond Neptune. This has been revealed by numerical calculations made by researchers at the Complutense University of Madrid and the University of Cambridge. If confirmed, this hypothesis would revolutionise solar system models.
Astronomers have spent decades debating whether some dark trans-Plutonian planet remains to be discovered within the solar system. According to the calculations of scientists at the Complutense University of Madrid (UCM, Spain) and the University of Cambridge (United Kingdom) not only one, but at least two planets must exist to explain the orbital behaviour of extreme trans-Neptunian objects (ETNO).
The most accepted theory establishes that the orbits of these objects, which travel beyond Neptune, should be distributed randomly, and by an observational bias, their paths must fulfil a series of characteristics: have a semi-major axis with a value close to 150 AU (astronomical units or times the distance between the Earth and the Sun), an inclination of almost 0° and an argument or angle of perihelion (closest point of the orbit to our Sun) also close to 0° or 180°.
Yet what is observed in a dozen of these bodies is quite different: the values of the semi-major axis are very disperse (between 150 AU and 525 AU), the average inclination of their orbit is around 20° and argument of Perihelion -31°, without appearing in any case close to 180°.
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