With a diameter of 1,440 miles, Pluto is farthest from the sun. While major planets make roughly circular orbits, Pluto ...

The debate over Pluto’s planetary status has been ongoing since its reclassification as a “dwarf planet” in 2006 by the ...

On August 24, 2006, Pluto ceased to be considered a planet. A mixture of rock and ice located in the Kuiper Belt, a region of icy objects beyond the orbit of Neptune. This demotion ...

Pluto, therefore, is not the gravitationally dominant object in its neighborhood — and thus, not a planet, according to the new definition. But this framework drew immediate criticism.

According to the IAU, a dwarf planet is as related to a planet as an asteroid is -- not at all. This hard definition has been drawing criticism since the IAU demoted Pluto in a 9-8 vote in 2006.

On January 17, 2006 the New Horizons mission will launch for Pluto, the last unexplored planet of the solar system — or is it? Some scientists now claim that Pluto does not deserve its planetary ...

Planet X or not, Pluto existed. Smaller than the Moon, but inhabiting the realm of the giant planets, it defied our notions regarding the architecture of the Solar System.

Planet X or not, Pluto existed. Smaller than the Moon, but inhabiting the realm of the giant planets, it defied our notions regarding the architecture of the Solar System.

Two of the objects that at one point looked like they might become full-fledged planets will now join Pluto as dwarfs: the asteroid Ceres, which was a planet in the 1800s before it too got demoted ...

Pluto may have lost its status as a full-fledged planet in 2006, but that doesn't mean it's a joke of a world this April Fools' Day and the folks behind Pluto TV want to make that clear.

Pluto, once considered the ninth planet of our solar system, has been a topic of intrigue since its reclassification as a ...

The US state of Arizona has taken the unusual step of naming a state planet. Even more unusually, they have chosen Pluto – which is not a planet – as their representative in the solar system.