The newfound exoplanet, called Kepler-139f, is a gigantic world roughly twice the mass of Neptune and 35 times the mass of ...

A telescope has discovered a new world on the edge of the Milky Way – potentially confirming the ‘Planet X’ theory. Beyond ...

The Fifth Planet sounds like a great name for a sci-fi movie -- perhaps a sequel to the 1997 movie "The Fifth Element." But the fifth planet may be real; a hypothesized giant world that was flung ...

About 500 light years away, the fifth planet orbiting a small dim star called Kepler-186 has caught scientists' eyes as being not only roughly Earth-sized, but also within what's called the ...

Statistically, some of the most successful dynamical evolution simulations have initially included a hypothetical fifth giant planet, of ice giant mass, which gets ejected by a gas giant during ...

Hypothetical Planet 9 accounts for the movement of several trans-Neptunian comets, asteroids, and dwarf planets, but scientists can't find it.

Because the hypothetical Planet 9 only receives a fraction of its energy from the sun, it might be easier to pick up in the infrared band as an emissive object rather than looking for the light it ...