The elusive Planet Nine, which is theorized to be lurking somewhere in the outer reaches of the solar system, may not be a planet after all, a new study suggests. Instead, what we assumed to be a massive object could be evidence that gravity doesn’t work like we thought it does. But the new theory doesn’t sit well with everyone.
The Planet Nine hypothesis, first proposed in 2016, argues that the unusual orbits of objects in the Kuiper Belt beyond Neptune, which seem to be being pulled away from the sun, can be explained by the presence of an undiscovered ninth planet up to 10 times more massive than Earth. Astronomers have been looking for Planet Nine ever since. However, despite searching almost half of the night sky, they have so far come up empty-handed.
In the new study, published Sept. 22 in The Astronomical Journal, researchers proposed another explanation for the gravitational anomalies observed in the outer solar system — that there aren’t any anomalies. Instead, the team shows that the inconsistencies disappear completely when applying an alternative concept of gravity known as modified Newtonian dynamics (MOND).
Occam says “sure, bud”
If you consider only the case of “planet 9”, but the theory also does a great deal to simplify the question of dark matter. If I understand it correctly, this theory implies simply that there is an additional force which we have been lumping in with gravity so far.
I look forward to seeing some controlled experiments test this hypothesis.
The problem with mond is that it doesn’t agree with observations. The prime example is that galaxy merger currently in progress (forget the name). A particle based dark matter would pass through the merger while the gas would interact and slow down, and that’s exactly what we see. The behavior is incompatible with mond. There are other examples but that one is pretty damning.
Bullet cluster?