Pluto
Pluto is the dwarf planet whose 2006 demotion from full planetary status sparked a lasting online fandom, protest sites, and the verb 'plutoed.' The 2015 New Horizons flyby revived it as an internet-wide sympathy meme when close-up photos revealed a heart-shaped, dog-face-like surface.
Overview
Pluto is a small icy body in the Kuiper Belt that was reclassified as a dwarf planet in 2006, a decision that sparked an unusually loud online reaction2. Widespread description of the move as a demotion led to online petitions and a new coined verb, 'to pluto,' which the American Dialect Society named 2006 Word of the Year with the definition 'to demote or devalue someone or something'1.
The Pluto meme picked up a second wave in July 2015 when the New Horizons probe returned the first close-up photos of the dwarf planet, showing a reddish surface with a heart-shaped region that many said looked like the Disney cartoon dog Pluto, spawning Photoshop edits and sympathy captions on Twitter, Tumblr, and Reddit3.