The IAU today made history demoting Pluto from a major planet to
the less prestigious class of dwarf planet.
Here is an excerpt from an article on yahoo.

For now, membership will be restricted to the eight "classical"
planets in the solar system: Mercury, Venus, Earth, Mars, Jupiter,
Saturn, Uranus and Neptune.

Much-maligned Pluto doesn't make the grade under the new rules for a
planet: "a celestial body that is in orbit around the sun, has
sufficient mass for its self-gravity to overcome rigid body forces
so that it assumes a ... nearly round shape, and has cleared the
neighborhood around its orbit."

Pluto is automatically disqualified because its oblong orbit
overlaps with Neptune's.

Instead, it will be reclassified in a new category of "dwarf
planets," similar to what long have been termed "minor planets." The
definition also lays out a third class of lesser objects that orbit
the sun — "small solar system bodies," a term that will apply to
numerous asteroids, comets and other natural satellites.