International Astronomical Union
By: Emily Del Zotto
About the IAU
- Founded in 1919
- 11447 members in the IAU
- 96 countries participate in research
- Mission is to promote and safeguard the science of astronomy in all the aspects through international cooperation.
- How the IAU views the solar system changed in 1992 on August 30th.
- The view changed after the discovery of the objects orbiting beyond Neptune in what is often referred to as the transneptunian region.
- Planet, dwarf planet, and SSSBs (small solar system bodies) are all officially new definitions of the IAU.
- The IAUs view of the universe continues to evolve with changes made by observations, measurements, and theory.
Inferior planets - inside Earth’s orbit
Superior planets - outside Earth’s orbit
Inner planets - inside the asteroid belt
Outer planets - outside the asteroid belt
Gas giants - sharing the gaseous structure (like Jupiter)
Why is pluto not a planet?
Dwarf Planets and Small solar system bodies
It was agreed that planets and dwarf planets are two distinct classes of objects. Dwarf planets are planetary mass objects orbiting the Sun that are massive enough to be rounded by their own gravity, but are not planets or satellites. Unlike planets, these bodies have not cleared the neighborhood around their orbits, and their paths sometimes cross with other, often similar, objects.