Scientists Think an Earth-Like Planet May Be Hiding in Our Solar System

The behavior of trans-Neptunian objects indicates (according to current physical laws, i.e. Gravitation/General Relativity) the presence of a hidden world. This celestial object would be no greater than 3 times the mass of the Earth and no farther than 500 astronomical units ( 7,5 x 10¹⁰ km) from the Sun.