But that still doesn’t make it obvious that we’ll be spotting the planet anytime soon.

That can be read in a new study which has yet to undergo peer review, but can already be viewed online. In the study, the scientists who presented the first clues to the existence of Planet X years ago state that the evidence for the mysterious planet’s existence is still robust. And they determine more accurately where this planet may be.

How it started

Several years ago, astronomers Mike Brown and Konstantin Batygin made a remarkable discovery. They encountered six Kuiper belt objects, all of which have elliptical orbits and follow the same direction in physical space. Bizarre coincidence? Almost impossible, Brown argued. “The probability that this is a coincidence is only 0.007 percent. In short, it can hardly be a coincidence. There must be something that determines the course of these objects.” But then what? The researchers examined various scenarios and came to a spectacular conclusion. Somewhere on the edge of the solar system, a hitherto unknown large planet is said to reside.

Big attention

The mysterious planet was soon referred to as Planet X. Countless media wrote about it and people worldwide marveled at the idea that such a large object could be hidden from us in our own solar system. “I honestly never thought that our calculations would capture the imagination of the general public so much,” Batygin tells Scientias.nl.

Follow-up research

Scientists also got caught up in Brown and Batygin’s calculations. And while some concluded that there must indeed be a ninth planet hidden in our solar system, others questioned the clustering of Kuiper belt objects put forward as evidence by Brown and Batygin. This clustering would not be the result of a mysterious planet, but of a so-called observer bias. “It’s actually a very simple concept,” Batygin explains. “In fact, the idea is that you can only discover celestial bodies in places where you look for them. So if you have a study that only looks at one part of the universe, it can lead to the discovery of a population of objects that appear to be clustered.”

Small chance

In a new study however, Brown and Batygin firmly undermine that perceived observer bias. “We simulated the combined observer bias of all studies in which distant Kuiper Belt objects were discovered and found that the probability that the clustering (which Brown and Batygin observed and appears to indicate the presence of a ninth planet) is a false alarm. is between 0.2 and 0.4 percent.” Thus, the evidence for Planet X’s existence is still robust.

Track

But Brown and Batygin take their new study one step further. They use the observations of the Kuiper Belt objects mentioned above to more accurately determine the properties and orbit of Planet X. Thus, based on all this data, the planet’s mass is determined to be about 6.2 Earth masses. In addition, there are indications that Planet X is venturing closer than previously thought. When the planet (in its elliptical orbit) is furthest from the sun, the distance between the sun and Planet X is 380 AU (1 AU is the distance between the Earth and the sun). And when the planet is closest to the sun, it is about 300 AU from our parent star. The inclination angle of the orbit – or the angle it makes relative to the Earth’s orbital plane – is estimated to be 16 degrees.

treasure map

And so, based on the available data, we have a much more accurate picture of Planet X’s possible orbit. Mike Brown jokingly reports that the research results in a ‘treasure map’. But that doesn’t mean the treasure – Planet X – is up for grabs. First of all, the researchers present not one orbit, but several orbits, one of which is slightly more plausible than the other. “So there is a wide range of possible orbits and even the less plausible orbits cannot be ruled out in any way,” Batygin warns. In addition, each orbit is basically a string of possible locations and we have no idea where the planet is right now. So while it can certainly be good news that Planet X is probably closer than thought and we now also have a slightly better defined search area, it is not obvious that we will also find the planet any time soon.

Vera C. Rubin Observatory

And yet, Batygin is very hopeful that Planet X will be found sometime in the next few years. For example, based on what we now know about the alleged planet, it could be detected by the under construction Vera C. Rubin Observatory in Chile. The observatory should see first light next year.

Science at its best

It is almost certain that the research of Brown and Batygin will be re-examined by other scientists in the meantime. Because that’s science at its best, says Batygin. “And that’s what makes it so much fun!”

Amid all the calculations and discussions, pending the actual detection of Planet X, there is of course always the possibility that the planet does not exist. It would undoubtedly be a bit of a shock for Brown and Batygin, but somehow the conclusion that Planet X is a mirage could also be very exciting. “If Planet X doesn’t exist, the number of open questions about the outer reaches of our solar system suddenly increases,” Batygin said. “And that in itself is very interesting. Because remember, the clustering of the orbits of Kuiper Belt objects is just one clue to Planet X’s existence. If Planet X isn’t there, what causes the perihelion of distant Kuiper Belt objects to shift? What is the source of the retrograde Centaurs? Without Planet X, all those questions remain unanswered. So in that sense it would be both disappointing and exciting if Planet X turns out not to exist.”