Pluto may no longer be a planet but scientists say the solar system may very well have its replacement after all.

As per Mashable, there is new data that implies the presence of a new and big planet -- nicknamed Planet Nine -- that also orbits the sun along with the eight other known planets, albeit once every 10,000-20,000 Earth years. Its size is somewhere in between that of Earth and Neptune.

"Throughout the galaxy, the most common type of planet is between the mass of the Earth and the mass of Neptune, and isn't it weird that we don't have this type of planet? And, it turns out, this is exactly what we have," the study's co-author, Mike Brown, told the news outlet.

As such, Brown said, the mysterious planet makes the solar system more similar to the other systems found in the galaxy.

Planet Nine's existence was determined through the observation of the movements of "dwarf planets," as well as other small objects circling the sun.

The researchers observed that the dwarf planets were affected by a gravitational force, which they deduced could be coming from a yet-unseen planet.

Right now, Brown and his co-author Konstantin Batygin have been unable to see Planet Nine directly yet. They are still in the process of proving its existence via telescopes, as per Fox News Latino.

Considering that Planet Nine is still a theory, there have been speculations over whether the scientists' claims had a solid foundation. Previous claims by other researchers about the existence of "Planet X" had met dismissals by some in the scientific community.

"If you say, 'We have evidence for Planet X,' almost any astronomer will say, 'This again? These guys are clearly crazy.' I would, too," Brown noted, according to AAAS Science. "Why is this different? This is different because this time we're right."

Some scientists not involved in the study have reportedly confirmed that Brown and Batygin's calculations are sound, which adds to the duo's confidence in their theory.

Incidentally, Brown is one of the key persons who declared Pluto as a dwarf planet rather than a full-fledged one.

Theories of the existence of a planet beyond Pluto emerged a few years ago, spurred by Brown and his colleagues' discovery of a 600-mile-wide icy formation 8 billion miles outside the Kuiper belt. It was later validated by Chadwick Trujillo and Carnegie Institution for Science's Scott S. Sheppard in 2014, as per The New York Times.

Last year, it was reported that there may be two planets beyond Pluto, based on the calculations from the Complutense University of Madrid (UCM, Spain) and the University of Cambridge (UK), according to EarthSky.org. This theory still needs further investigation.

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