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 ...

While this research has failed to spot the fifth force, it does offer more evidence of how precise observations can reveal what's hidden in the Universe – and how asteroids can play an important ...

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 ...