Researchers at the California Institute of Technology (CalTech) in Pasadena say they now have “solid evidence” that there is a ninth planet — “Planet X” — about the size of Neptune lurking in the fringes of our solar system.
According to CalTech researchers Konstantin Batygin and Mike Brown, the new planet — which they call Planet 9 — has not been observed directly with a telescope, but latest mathematical calculations and computer models give convincing evidence that a gas giant about the size of Neptune and with a mass about ten times Earth, which completes an orbit of the Sun approximately every 15,000 years, lurks in the fringes of our solar system.
“We have found evidence that there’s a giant planet in the outer solar system,” Brown told Popular Science. “By ‘giant’ we mean the size of Neptune, and when we say ‘outer solar system’ we mean 10 to 20 times farther away than Pluto.”
Brown, whose discovery of Eris — a trans-Neptunian object about the size of Pluto — led to the realization that Pluto was not really a planet, but only one of several bodies in our solar system later reclassified as dwarf planets, explained that new planet is likely about 5,000 times the mass of Pluto.
Alluding to objections that followed reclassification of Pluto as a dwarf planet, Mike Brown (@PlutoKiller), said,”All those people who are mad that Pluto is no longer a planet can be thrilled to know that there is a real planet out there still to be found.”
According to the researchers’ calculations, the mysterious Planet X orbits our Sun far beyond Neptune and it takes it about 10,000 to 20,000 years to complete a single orbit of our Sun.
The closest approach (perihelion) of the hypothetical planet to our Sun is about 200 astronomical units (AUs), about seven times the closest approach of Neptune. The farthest distance of the hypothetical planet in its orbit (aphelion) around the Sun is estimated at about 600 to 1200 AUs, beyond the Kuiper belt.
The major evidence that the planet exists comes from observations of the pattern of alignment of six previously known astronomical bodies that follow an eccentric orbital path around our Sun beyond Neptune.
When the six bodies come closest to the Sun, they show a pattern of alignment of their orbits that could only be explained by the gravitational influence of another body in remote eccentric orbit, according to the researchers.
Explaining the alignment of the orbits of the six objects, Brown said, “You can think of them like different hands on the clock. They’re all moving at different rates in the same direction, and every once in a while you look up and they are all in the same spot.”
The scientists estimated that there is only 0.007 percent probability – or one in 15,000 chances – that the observed alignment is due to chance or coincidence. According to the researchers, only the gravitational influence of another massive body could explain the alignment of the elliptical orbits of the six objects.
The researchers believe that the planet may have been ejected from the inner to the fringes of our solar system about 4 billion to 4.5 billion years ago, where it settled into an elliptical orbit after its was slowed down in its escape trajectory by gas which existed around our solar system at the time.
“There would have been a gas nebula around the solar system at the time that would have slowed it down as it plowed through the gas, putting it into this eccentric orbit,” Brown said.
The researchers have reported their findings in a paper titled, “Evidence for a distant planet in our solar system,” published on Wednesday in the Astronomical Journal.
The researchers plan to use the 8.2-meter Subaru telescope in Hawaii to confirm their theoretical inferences. They expect to find the new planet within five years of search with the telescope.
They said they could have remained silent about their findings while conducting telescopic searches to confirm the existence of the planet. But they are making the evidence known because they would like other researchers to contribute to the search for the planet.
“We could have stayed quiet and quietly spent the next five years searching the skies ourselves and hoping to find it,” Brown said. “But I would rather somebody find it sooner, than me find it later.”
“I want to see it. I want to see what it looks like. I want to understand where it is, and I think this will help,” he added.
[Image via NASA/JPL-Caltech]