Just exactly what is Pluto now? Excuse my ignorance I'm not really into astronomy.
The International Astronomical Union (IAU) decided on 3 classifications of bodies orbiting the Sun on Aug 24, 2006:
Planets (also called major planets): This is a celestial body that: (a) is in orbit around the Sun; (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a nearly round shape (due to a hydrostatic equilibrium); and (c) has cleared the neighborhood around its orbit. There are 8 of these in the solar system: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.
Dwarf planets: This is a celestial body that: (a) is in orbit around the Sun; and (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a nearly round shape (due to a hydrostatic equilibrium); but (c) has not cleared the neighborhood around its orbit; and (d) is not a satellite of another planet. As defined, the solar system has probably has at least one dwarf planet in the main asteroid belt (Ceres), Edgeworth-Kuiper Belt (Pluto and Eris); and Oort Cloud (possibly Sedna). In addition, the "dwarf planet" Pluto is recognized as a prototype of a new class of trans-Neptunian objects also called "Kuiper-belt objects."
Smaller Solar System Bodies: This category collectively refers to all other celestial bodies orbiting the Sun (proper name: Sol) including asteroids (also called minor planets), comets, meteoroids, and satellites of the major/dwarf planets.
Pluto's demotion from major planet classification is not the first time this has happened to such smaller bodies in the solar system. When the first asteroids were discovered, they were called planets (Ceres was the first discovered in 1801). However as more and more of these objects were discovered (in orbit about the Sun between the orbits of Jupiter and Mars), it was realized that a new classification should be given to these smaller objects. After that (in the 1840s), these object were called minor planets or asteroids.
By the way, professional astronomers only use the names of objects in the sky as voted and agreed upon by the IAU. One cannot buy a name for a star and expect that name to be recognized by professional (and amatuer) astronomers. Buyer beware!
