%0 Journal Article
%T The Moon Meets All Requirements of the IAU Definition for ¡°Planet¡±
%A David G. Russell
%J International Journal of Astronomy and Astrophysics
%P 291-302
%@ 2161-4725
%D 2017
%I Scientific Research Publishing
%R 10.4236/ijaa.2017.74024
%X The Earth-Moon system has often been characterized as having some characteristics of a ¡°double planet¡± system. It is demonstrated that while the orbital barycenter of the Earth-Moon pair lies inside the radius of the Earth, the Moon does meet all three requirements of the IAU definition for ¡°planet¡± and therefore the Moon can correctly be identified as the Solar System¡¯s 9<sup>th</sup> planet. In order to avoid confusion by this development it is necessary to add definitions for ¡°double planet¡±, ¡°double dwarf planet¡±, ¡°satellite planet¡±, and ¡°satellite¡± to complement the International Astronomical Union definitions for ¡°planet¡± and ¡°dwarf planet¡±. The Earth-Moon system meets the requirements of a ¡°double planet¡± system while the Pluto-Charon system meets the requirements of a ¡°double dwarf planet¡± system. In order to extrapolate sub-stellar taxonomy to exoplanetary systems, general formation mechanisms (star-like gas collapse in molecular clouds vs. proto-planetary disk formation) should be included in the definitions for the various classes of sub-stellar mass bodies.
%K Moon
%K Earth
%K Planet
%K Dwarf Planet
%K Double Planet
%K Satellite
%K Rogue Planet
%K Brown Dwarf
%U http://www.scirp.org/journal/PaperInformation.aspx?PaperID=81133