A new research, published on August 10, 2015, suggests a cluster of icy bodies located in the same areas as Pluto, might prove our early Solar System was inhabited by a fifth giant planet. During Neptune's migration, 4 billion years ago, the ice giant might have jumped into it's current orbit and scattered a cluster of it's satellites into the outer solar system, the Kuiper belt.
A cluster of about thousand icy rocks, the so-called "kernel" of the Kuiper belt, is an old mystery for astronomers. The rocks hover close to one another and never change it's moving direction from the same orbital plane as the planets, unlike other icy bodies that constitute the belt.
Previous research suggested the objects bound this way could have formed during a violent collision of bigger parent bodies. However, it turned out the collisional families would have to be stretched along the Kuiper belt, which proved the proposition invalid.
