World astronomers have declared that Pluto is no longer a major planet under new guidelines. It is now considered a "dwarf planet".
History From its discovery in 1930 until 2006, Pluto was counted as the Solar System's ninth planet. In the late 20th and early 21st centuries, however, many objects similar to Pluto were discovered in the outer solar system, notably Eris, which is 27% more massive than Pluto.
On August 24, 2006 the International Astronomical Union(IAU) defined the term "planet" for the first time. This definition excluded Pluto, which the IAU reclassified as a member of the new category called dwarf planets along with Eris and Ceres. So now Pluto is just the second-largest known dwarf planet in the Solar System (after Eris).
IAU Decision (August 24, 2006)
According to the International Astronomical Union's 2006 redefinition of planet, there are three main conditions for an object to be called a 'planet'.
1. The object must be in orbit around the Sun.
2. The object must be massive enough to be a sphere by its own gravitational force. More specifically, its own gravity should pull it into a shape of hydrostatic equilibrium.
3. It must have cleared the neighborhood around its orbit. Pluto fails to meet the third condition.
The IAU further resolved that Pluto be classified in the simultaneously created dwarf planet category, and that it act as prototype for a yet-to-be-named category of trans-Neptunian objects, in which it would be separately, but concurrently, classified. Prior to this decision several other definitions had been proposed, some of which might have ruled out planetary status for Earth or Mercury or may have classified several of the asteroids as planets. This version was democratically chosen in a successful attempt at avoiding these non-traditional results.
See related link for the IAU official reason.
Pluto is no longer a planet but there are dwarf planet Pluto is considered a dwarf planet
no Pluto is not a planet
Pluto is NOT a planet it is a dwarf planet
Pluto is not a planet
Pluto is not a planet its a dwarf planet
no Pluto the dog was not named after the planet Pluto.
There is a few facts about the planet Pluto. Pluto is the smallest planet and it is the coldest planet.
The planet Neptune is the closest Planet to Pluto. The dwarf planet Haumea is the closest dwarf planet to Pluto.
Pluto is a dwarf planet
Pluto is a planet!
Pluto is not a planet
dwarf planet Pluto
neptuneNeptune is the closest to Pluto. Uranus is the second closest planet to Pluto. Saturn is the third closest planet to Pluto. Jupiter is the forth closest planet to Pluto. Mars is the fifth closest planet to Pluto. Earth is the sixth closest planet to Pluto. Venus is the seventh closest planet to Pluto. Mercury is the most furthest away from Pluto. The Sun and the moon are not considered as planets. The planet Pluto is also not considered as a planet.