- Astro-Taxonomy: Sizing up the Planets - Provides a formal definition of a planet, information on planetary classification and cosmogony.
- Definition of Planet - Wikipedia - Article describes the history and present controversy surrounding the word and its applicability to various objects.
- International Outer Planet Watch - A program to study the time variability of the outer planets.
- Planet Facts - Provides photographs and information about each planet in the solar system.
- Planets Formation - Article from a book by Angel Fernando Vitoria.
- Welcome to the Planets - Images from NASA's planetary exploration program.
