Astronomers who suspect a hidden planet called "Planet X" or "Planet Nine" affect the comings and goings of icy objects beyond Neptune. We think we could soon look at this mysterious and distant world.
In a 92-page article to be published in Physics Reports, a team of Caltech researchers reviews evidence of Planet X's existence and describes a world closer and smaller than previously thought.
Almost a decade after poor Pluto was demoted from the ninth planet to dwarf planets, an intriguing article was published by one of the astronomers "killers of Pluto" and his alumni. The hypothesis suggested a larger, invisible even further on the edge of our solar system.
"In essence, three years ago, we knew that the orbits of objects far removed from the Kuiper belt were clustered," said Konstantin Batygin, the junior half of the duo, in an email on Tuesday. "And we were able to demonstrate with the help of computer simulations that the only reasonable reason for this reunion was the existence of Planet Nine."
The idea is that the distant objects mentioned by Batygin are influenced by the gravitational pull of a large planet orbiting somewhere in the outer field of the solar system.
Batygin of CalTech, his former mentor, Michael Brown (aka "PlutoKiller"on social media) and their colleagues, Fred Brown and Juliette Becker of the University of Michigan have an update to offer us, and if their theory is water resistant, it would radically redefine our vision of our solar system.
"Our new efforts, both theoretical and numerical, suggest that in the original article we overestimate the parameters of Planet Nine," said Batygin.
The new analysis paints a portrait of a planet whose mass is five times that of the Earth and located at about 400 astronomical units (AU). For comparison, Pluto is only about 40 AU from us. The authors also conclude that the invisible planet will likely be a super-rocky Earth rather than a gas giant. But the outlook for habitability is of course very low, just as the sun would be at such a distance.
"Although this analysis does not say anything directly about Planet Nine's presence, it nonetheless indicates that the hypothesis rests on a solid foundation," said Brown, professor of global astronomy at Caltech.
The paper also seeks to answer some of the criticisms of Planet Nine 's hypothesis and other explanations for the strangeness observed in the Kuiper belt. For example, Batygin and his colleagues are not convinced by a competing theory that a massive disk of debris beyond Neptune could explain the strange orbits of distant objects of the Kuiper belt and a super -Invisible land.
"The strongest argument in favor of Planet Nine is that all independent data sources can all be explained by a proposed new planet having the same properties." In other words, there are many reasons to believe that Planet Nine is real, not only, "said co-author Fred Adams.
If planet X exists and fits the terms of this last document, it will also be a key missing element of our solar system.
As the catalog of known exoplanets around other stars has rapidly developed over the last decade, it has become increasingly clear that our system is actually quite unusual. Indeed, the rocky highlands seem to be very common elsewhere, but they do not exist in our solar system.
"Planet Nine will be the closest thing we can find in a window to the properties of a typical planet in our galaxy," said Batygin.
But he admits that all speculation around Planet X will remain unchanged until someone finally discovers it.
"The prospect of seeing real Planet Nine images is absolutely electrifying," he says. "Although the astronomical discovery of Planet Nine is a daunting challenge, I am very optimistic that we will be imagining it over the next decade."