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

Since Pluto is surrounded by many other KBOs, it hasn't achieved gravitational dominance in its region. As a result, it doesn't fulfill criterion 3, meaning it can no longer be classified as a planet.

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

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.

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.

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.

Two of Pluto's midsize moons may be made of the guts of its largest moon, Charon, new research suggests.

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.

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 ...

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.

For decades people searched for X, the rumored 8th planet, until it was finally found by a Kansas farmboy. It turned out, however, it wasn't quite a planet.

The International Astronomical Union in Prague ruled today that the much-maligned Pluto no longer qualifies as a planet under historic new guidelines, thereby stripping Pluto of the planetary ...