- Gravity Rules: The Nature of Planethood - Article discussing possible definitions that qualify objects, such as Pluto and Sedna in the Kuiper Belt, as being planets or not.
- Is Pluto a Giant Comet? - Discusses related discoveries and excerpts.
- Pluto - Argues that Pluto is the most important Kuiper Belt object, not the least important planet, based on its orbit and other properties. From astronomer Dave Jewitt, who studies comets and other primitive solar system bodies.
- What is a Planet - Reviews newly-discovered objects that stretch the definition of the term, including massive superjupiters, free-floating planets, and other exoplanets. Suggests a definition based on the way an object is formed. From astronomer Gibor Basri.
Media publications
- Astronomer Upset at New Planet Proposal - Washington Post article describes Michael Brown's disagreement with a proposal to expand the definition of a planet to include, among others, his own discovery. (Published 2006-08-19 00:00:00)
- CBS News: Pluto: Planet Or Junk Snowball? - Outlines the history of the debate. (Published 2005-02-14 00:00:00)
- IAU Resolutions 5&6 - The International Astronomical Union's definition of a planet in the Solar System and ruling on the classification of Pluto. (Published 2006-08-24 00:00:00)
- Much ado about Pluto - News release from NASA affirming Pluto's planetary status. (Published 1999-02-17 00:00:00)
- National Geographic News: Pluto: Planet or Comet? - Discusses Pluto's similarity to other Kuiper Belt objects, and introduces a 5-way classification scheme for solar system objects to break down the lumping together of dissimilar planets. (Published 2001-02-23 00:00:00)
- PBS NewsHour: Pluto Debate - Reports regarding the controversy over Pluto's classification, focusing on pop culture influences and newsworthiness. (Published 2007-01-31 00:00:00)
- SciZone - Ontario Science Centre: Pluto: Planet or Not? - Brief nontechnical introduction to Pluto and similar objects such as Sedna and Quaoar, and a summary of the features that make Pluto different than the other planets. Includes a capsule summary of the arguments for and against calling Pluto a planet. (Published 2004-04-01 00:00:00)
- When Is a Planet Not a Planet? - Articles discusses the debate whether Pluto should be included among the planets. [Atlantic Monthly] (Published 1998-02-01 00:00:00)