Pluto

Pluto is a planet in the solar system, and is studied in Divination and Astronomy classes. Professor Trelawney owned an orrery that displayed all nine planets, including Pluto. It was her belief that Pluto could disrupt everyday life, which she taught to her students.

In the Department of Mysteries, there is a room full of planets. During the Battle of the Department of Mysteries, Luna Lovegood blew up the Pluto replica in this room to distract the Death Eaters pursuing them.

Behind the scenes

 * The International Astronomical Union changed the definition of "planet" in 2006, creating the new classification of "dwarf planet" to apply to objects that orbit the sun and have enough mass to assume a roundish shape, but are part of a region filled with many small objects like the asteroid belt or the Kuiper belt. Pluto, which is in the Kuiper belt, was thus demoted from a planet to a dwarf planet. However, Pluto would have been considered a planet in the Harry Potter series, which are largely set in the 1990s. It is also possible that the IAU redefinition never occurred in Harry's universe (or that the wizarding community simply wished to disregard it, as they did with the process of metrication) and that Pluto would still be classified a planet in the epilogue, the only part of the series set after 2006 (or 1998 for that matter).
 * Pluto is named after the Roman god of wealth and death, whose Greek aspect Hades was portrayed by Ralph Fiennes (Lord Voldemort) in the 2010 fantasy film Clash of the Titans and its 2012 sequel.

Appearances

 * Harry Potter and the Goblet of Fire
 * Harry Potter and the Order of the Phoenix