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 ...

Instead, a model about 10 times more likely at matching our current solar system began with five giants, including a now lost world comparable in mass to Uranus and Neptune.

(See if there is a giant hidden planet in our solar system.) One idea that had been floating around (so to speak) among planetary scientists, however, was the idea of the long-lost fifth giant ...

According to the 2011 model, the lost planet was an ice giant, made of elements such as carbon and oxygen, and similar in mass and composition to Uranus and Neptune, the ice giants in the Solar ...

They hypothesize that our solar system formed inside a massive space bubble, which was produced by a star 40 to 50 times the size of our sun. The research was published today in Astrophysical Journal.

The gas giant's core had already grown to be 20 times more massive than Earth just 1 million years after the sun formed, a new study suggests. "Jupiter is the oldest planet of the solar system ...

The original Nice model actually works better with five gas giant inner planets, but in those calculations, one of those planets is ejected out into interstellar space to become a rogue planet.

Evidence from the fragments of a destroyed asteroid suggests that the shift in the positions of the giant planets in our Solar System billions of years ago happened between 60-100 million years ...

Instead, a model about 10 times more likely at matching our current solar system began with five giants, including a now lost world comparable in mass to Uranus and Neptune.

A fifth giant planet was kicked out of the early solar system, according to computer simulations by a US-based planetary scientist. The sacrifice of this gas giant paved the way for the stable ...

Instead, a model about 10 times more likely at matching our current solar system began with five giants, including a now lost world comparable in mass to Uranus and Neptune.