Planet Nine could be a Super-Earth orbiting at 400 astronomical units

It has been a long-running debate amongst the astronomers whether our solar system consists of a ninth planet. Known as "Planet Nine," a team of researcher from Caltech has claimed that an unseen planet exists in the solar system based on the movement of other objects.

In their latest papers, the astronomers have discussed the existence of the Planet Nine. In support of their argument, the team has presented the orbits of Kuiper Belt Objects that appear to be circling an unseen planet. The new paper shows the observations that the clustering of Kuiper Belt Objects is well supported, making the team's case stronger.

"Though this analysis does not say anything directly about whether Planet Nine is there, it does indicate that the hypothesis rests upon a solid foundation," Mike Brown, professor of planetary astronomy at Caltech said.

The astronomers also believe that the Planet Nine could be five times the mass of Earth, making it similar to a super-Earth which is bigger than our planet but much smaller than Jupiter.

They also believe that the unseen planet could be closer than previously assumed. The paper suggests that the planet orbits at a distance of around 400 Astronomical units (AU), the distance between the Sun and the Earth.

"At five Earth masses, Planet Nine is likely to be very reminiscent of a typical extrasolar super-Earth," Konstantin Batygin, co-author of the paper, said in a statement. "It is the solar system's missing link of planet formation. Over the last decade, surveys of extrasolar planets have revealed that similar-sized planets are very common around other sun-like stars. Planet Nine is going to be the closest thing we will find to a window into the properties of a typical planet of our galaxy."