What date was Pluto not a planet?

Answer 1

The short answer is that the decision was ultimately made by the International Astronomical Union, or IAU.

The longer answer is that nobody actually ever decided Pluto wasn't a planet. You see, before August 24th, 2006, there was no official definition of what is and is not a planet. As more differences were noted between Pluto and the other eight planets in our solar system, the need for an official definition became more pressing. Eventually the IAU met and formulated a definition upon which they could all agree. This definition excluded "planets" with characteristics like Pluto has, thus changing its classification from planet to dwarf planet.

Answer 2

In 2006 the International Astronomical Union decided Pluto wasn't a planet after all. The object was named a "dwarf planet" because it doesn't clear the path of all the surrounding objects in its orbit but is also not a satellite of another object.

Answer 3

"The enigmatic, icy world spotted in 1930 has been given the official moniker of 134340 Pluto. It has been lumped among 136,562 asteroids and other small bodies by the Minor Planet Centre (MPC), which is part of the Paris-headquartered International Astronomical Union (IAU)."

This is a link to the good explanation I got that from.
http://www.abc.net.au/news/newsitems/200609/s1740456.htm

Answer 4

In 2006, the International Astronomical Unit (IAU) put up criteria, a definition, for the term 'planet.' Pluto is now considered a dwarf planet because it does not meet all the criteria coined by the IAU.

1. is in orbit around the Sun,
2. has sufficient mass to assume hydrostatic equilibrium (a nearly round shape), and
3. has "cleared the neighbourhood" around its orbit.

Answer 5

The International Astronomical Union (IAU) in Prague, Czech Republic, in August 2006 stated that, in the Solar System, a planet is a celestial body which:

1. is in orbit around the Sun,
   
2. has sufficient mass to assume hydrostatic equilibrium (a nearly round shape), and
   
3. has "cleared the neighborhood" around its orbit.
   

Answer 6

Pluto was reclassified as a dwarf planet on August 24, 2006 by the International Astronomical Union.

Answer 7

About 2 years ago... They said it was just a star

Answer 8

Early last year, or the late year before that.

Answer 9

The International Astronomical Union declared in 2006 that Pluto should be reclassified as a dwarf planet.

Answer 10

In the year 2006.