Suggestions of a ninth planet in our Solar System have been rumbling on for years now.
Some astronomers argue that the clustering and orbital tilt of a group of trans-Neptunian objects indicate gravitational shepherding by an unknown planet.
Suggestions of a ninth planet in our Solar System have been rumbling on for years now.
Some astronomers argue that the clustering and orbital tilt of a group of trans-Neptunian objects indicate gravitational shepherding by an unknown planet.