The solar system may actually hold ten or 11 planets, according to a new study which poses questions for the researchers who detected evidence of "Planet Nine" earlier this year.
In January, Konstantin Batygin and Mike Brown from the California Institute of Technology (Caltech) claimed there was an icy world far beyond the dwarf planet of Pluto and believed to be up to four times as large and ten times as massive as Earth.
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Now those orbits have led scientists from Cambridge University and Spain to believe there could also be a Planet Ten and even Eleven, reports the Daily Telegraph.
Sverre Aarseth, from the Institute of Astronomy at Cambridge, and Spanish astronomers Carlos and Raul de la Fuente Marcos say the orbit of Planet Nine does not match up with the orbits of the Kuiper belt objects and so there has to be more large planets influencing them.
"We believe that in addition to a Planet Nine, there could also be a Planet Ten and even more," said Carlos de la Fuente Marcos.
However, not everyone is convinced by the findings.
"I think it's way too early to start speculating about a second planet but, in general, I am confused by their results," Caltech's Brown told the Daily Mail.
"We have a nearly identical analysis which shows nearly the opposite result. It is not obvious to me why they would get such a different answer."