Question

What decision did the international astronomical union make in august 2006

Answer 1

The IAU members gathered at the 2006 General Assembly agreed that a "planet" is defined as 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 hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit. This means that the Solar System consists of eight "planets" Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. A new distinct class of objects called "dwarf planets" was also decided. It was agreed that "planets" and "dwarf planets" are two distinct classes of objects. The first members of the "dwarf planet" category are Ceres, Pluto and 2003 UB

Answer 2

Answer: The international astronomical union formulated a new definition of what it means to be a planet and declassified Pluto as a planet in august 2006.

Explanation: Hi, on 24 August 2006, Pluto was declassified as a planet by The International Astronomical Union following a vote at their General Assembly in Prague. It was given the status instead as a 'dwarf planet', on account of its small size - smaller than the Moon - and highly elliptical tilted orbit which overlaps with that of Neptune.

The IAU formulated a new definition of what it means to be a planet.  

A planet 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 hydrostatic equilibrium (nearly round) shape, and

(c) has cleared the neighbourhood around its orbit.