User blog comment:LondonDauntlessCorvair963/Cool Facts About Random Stuff/@comment-5111283-20131230174328/@comment-4052371-20140101015834

According to Wikipedia, one of the main characteristics of a dwarf planet is that it has not yet become large enough to become the dominant astronomical object in its orbital region. Pluto's surrounded by a lot of Kuiper objects, some of which are about as large as it.