A new paper discusses the possible existence of an unseen planet in the outer solar system, the so-called "Planet X" or ...

Sedna has been cited as possible evidence for ... Computer simulations of the gravitational interactions of solar system bodies suggest that a hypothetical Earth-like planet explains all of ...

Sedna's odd orbit was not a one-off. It's these extreme trans-Neptunian journeys that have astronomers stumped. Based on what ...