Astronomers have found new arguments against the existence of the "ninth planet"

Astronomers have found new arguments against the existence of the "ninth planet"
Astronomers have found new arguments against the existence of the "ninth planet"

Computer simulations have confirmed an earlier hypothesis that explains the anomalies in the orbits of some trans-Neptunian objects not by the influence of a hypothetical planet, but by their own collective gravity.


Most bodies in the solar system move in stable and orderly orbits. However, a small group of distant trans-Neptunian objects stands out against this background. Their orbits do not experience the gravitational influence of Neptune itself, which makes them "detached" from the rest of the solar system. They are farther away than even the Kuiper Belt, which stretches roughly from the orbit of Neptune to Pluto, at a distance of 30 to 55 AU. (astronomical units equal to the average radius of the Earth's orbit). Their trajectories are elongated, and the orbital planes are inclined to the common plane of rotation of the Sun and planets.

The most significant of these objects is Sedna, which approaches the Sun by no more than 76 AU, and at a distant point goes to an impressive 937 AU. - more than five days. Well, the most famous explanation for the anomaly of their orbits connects it with the attraction of the still not discovered "ninth planet" of the solar system. However, it is not possible to find the elusive Planet X, so scientists are considering other hypotheses with equal attention.

For example, in 2018, Ann-Marie Madigan and her colleagues showed that the same effect can be created by the collective gravity of many trans-Neptunian objects themselves. In their motion, Sedna and other bodies from time to time come closer and interact, as a result of which they acquire their unusual, anomalous orbits. In a new article published in The Astronomical Journal, Anne-Marie Madigan and Alexander Zderic develop and refine this hypothesis.

With the help of a supercomputer, scientists were able to carry out large-scale modeling of the motion and gravitational interactions not only of small isolated trans-Neptunian objects, but also of neighboring massive planets. Having started their virtual rotation, astronomers soon noticed that the trajectories of small bodies really change and gradually come to the anomalous form that is observed in reality.

At the same time, the authors of the work note that for the implementation of such a scenario, the total mass of interacting objects should have been at least 20 Earth masses at the first stages. "In theory, this is possible," says Anne-Marie Madigan, "but it definitely contradicts the general idea." Perhaps the new observations will help find, if not the "ninth planet", then at least the missing trans-Neptunian objects.

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