The notion that only eight planets exist in our solar system is common knowledge, but evidence uncovered by a California based astronomer suggests there may exist a ninth planet, affecting the orbit of objects in space.
On Jan. 25, Michael Brown, astronomy professor from the California Institute of Technology (Caltech), gave a speech in the Rudder Forum at Texas A&M entitled “Planet Nine from Outer Space” as a part of the physics department’s Distinguished Lecture Series.
In January of 2016, Brown and fellow Caltech astronomer Konstantin Batygin proposed the existence of “Planet Nine,” a hypothetical major planet between the size of Earth and Neptune.
“[After the discovery of Pluto], other astronomers continued to make predictions [about new planets] until about 1992,” Brown said. “When I was in grad school, a paper [was published] that said ‘There are no new planets out there’ … in addition to this, in 1992, it was determined there was a bunch of stuff out there around Pluto.”
While there wasn’t a planet discovered in that area, Brown said the behavior of certain objects in space suggested there was something out there.
“When an object in the Kuiper belt orbits Neptune, sometimes it hits it and scatters,” Brown said. “So it scatters, but eventually it comes back to orbiting Neptune … and eventually it hits Neptune again, and scatters out even further away, towards the Sun.”
According to Brown, some of these objects did not behave according to the conventional model of gravity, which meant there was an object exerting its own gravitational force on the scattered objects.
“It was discovered that some of these objects clustered together,” Brown said. “But the argument that it was a planet [making them cluster] doesn’t work.”
Brown said he and Batygin began to work on explaining the cluster, writing equations on the board and tossing ideas about what could have caused the abnormal cluster. Everything came back to an object large enough to exert a gravitational force the size of a planet.
Brown and Batygin proposed that the existence of Planet Nine could explain the abnormal orbits observed of trans-Neptunian objects (TNOs), or any minor planets that orbit the sun beyond Neptune. The TNOs in question exist beyond the Kuiper belt, approximately 50 astronomical units (AU), or roughly four billion, six hundred and fifty million miles away from the sun.
“It would have taken an eccentric planet to cause this,” Brown said. “In that hypothesis, [our work] tells us there is a planet keeping all these objects in orbit. Like a mother planet keeping them in line.”
Despite feeling confident in their work, Brown said he needed more to confirm their hypothesis.
“To make sure we weren’t being stupid, we ran simulations about what the hypothetical planet could do,” Brown said. “At first, we were not convinced that we were actually right because [the simulations didn’t show exactly what they hypothesized]. And then, we realized it actually does make sense.”
Brown said the objects in question were shown to cross the orbit of Pluto, despite the fact that Pluto doesn’t come close enough to Neptune to pull the objects into its orbits. This showed that they had the position of the planet wrong, not the idea that the planet exists, according to Brown. However, they still couldn’t propose their hypotheses.
“Everyone who has ever stood up and said ‘I think there’s a new planet out there’ has been wrong,” Brown said. “So we sat down and said ‘What else do we know?’ … But it turns out there are these five objects perpendicular to the planet … which look like wings to Planet Nine, exactly where they were predicted to be.”
Brown said that was the moment when he realized his hypothesis had legs to it.
“Our jaws hit the ground,” Brown said. “This had become a legitimate prediction. There is a planet out there.”
Tests showing that the behavior of the objects in the Kuiper belt were not statistical anomalies or due to observational bias, but due to the existence of Planet Nine were then conducted , according to Brown.
“The data showed the chances that these were due to bias or anything else came out to 0.0001 percent,” Brown said. “So while there is always the chance that it’s not due to Planet Nine, it likely is.”
Due to the results of recent data, Brown said he and his fellow researchers now have a specific area to search for Planet Nine and some characteristics of what the planet could be like, including brightness and mass.
“Planet Nine is likely 10 times the mass of the Earth, the most common mass for any other known planet,” Brown said.
Brown said the technology available at Caltech will help tremendously in his search for Planet Nine, which he believes is near the constellation of Orion.
“I believe in the next few years we will find it,” Brown said. “We are surveying the region it is most likely in … I would say there is a 10 percent chance [we have the wrong area], but I am optimistic we would find it in the next year.”
The lecture was attended by professors, faculty and students alike, including Elad Dermer, electrical engineering sophomore, and Saul Barraza, computer engineering sophomore.
“I read about the lecture in an email,” Dermer said. “I thought it seemed interesting so I came.”
Barraza said Dermer told him about the lecture a mere 20 minutes before it was slated to begin, and deciding to join Dermer.
Both said they enjoyed the lecture, which answered several questions they about about the topic.
“It’s a subject you hear a lot about in the news,” Dermer said. “And to actually be able to come to campus and hear about it, that’s very cool.”
Barraza said that while astronomy is not his field of study, he found himself very entranced by Brown’s presentation and explanations.
“I had never seen anything like the maps he showed,” Barraza said. “All the statistical analysis stuff, it was all just really cool to see. Honestly, what was probably my favorite thing was the simulations he showed.”