Two astronomers – Konstantin Batygin and Mike Brown – believe they have found evidence for a ninth planet in our own Solar System. Since the “demotion” of Pluto the official planet count is eight and all recent discovered planets are exoplanets.
What is the argument for the existence for a ninth planet in our Solar System? Batygin and Brown have studied the orbits of the so-called Kuiper belt objects, which include Pluto, Sedna and Makemake. With a computer simulation they found that the current orbits are best explained by the existence of another planet.
This postulated planet has, according to Batygin and Brown, a mass of ten times that of Earth and is located twenty times further away than Neptune – at about 56 billion miles or 600 AU. In comparison Uranus has a mass of 15 Earths and Neptune of 17.
Of course, the fact that a computer simulation indicates the existence of Planet IX, is on its own not sufficient to say it actually exists. Hence Batygin and Brown have begun to actually observe this planet. They know the rough orbit of this planet but not were its current location is. (You can compare this by having a map, but not knowing a particular person is in the mapped area.)
It is important to note that this simulation can only give insight in the orbit and mass of Planet IX, but nothing about its composition – though I guess it’s an ice giant like Uranus and Neptune. Nor does we now whether this planet has moons. However, I do not think we will find life there, let alone intelligent life, it is too cold.
Assuming Planet IX does exist, will it be relevant for space colonization? Not this century, I suspect. But in the long run it might be a step between the colonization of our Solar System and interstellar travel.