Minor Planets - A case study

Minor planet is a term used to refer to a celestial object – that is not a planet or comet – which orbits the Sun. Found in 1801 Ceres also known as a dwarf planet was the first minor planet discovered. The term minor planet has been in use since the 1800’s. Planetoids asteroids and minor planets have all been used interchangeably but the situation became even more confusing when the International Astronomical Union (IAU) committee reclassified minor planets and comets into the new categories of dwarf planets and small solar system bodies. At the same time the IAU created a new definition of what a planet is and Pluto was reclassified as a dwarf planet. Hydrostatic equilibrium – the ability to maintain a roughly spherical shape – is what separates dwarf planets from the more irregularly shaped small solar system bodies. The names become even more confusing because the IAU still recognizes the use of the term minor planets.