Who you calling a dwarf? Pluto flyby reopens debate about its 'planet' status

Passion still flare on both sides, with some saying it should never have been a planet to begin with while others call the dwarf planet designation 'vindictive'

Pluto lost its title as our ninth planet nearly a decade ago, not long after Nasa launched a 3bn-mile mission to the celestial body that reached its destination this week, and not nearly enough time for passions to cool over its demotion.

Nasa's historic New Horizons mission to Pluto has revived those passions, if not the official debate, between scientists who can't agree about the definition of a planet. In 2006 the International Astronomical Union took up the question, and a handful of voters decided the issue. Pluto was reclassified from one of the nine planets to a new category, the dwarf planet, based on its size and the discovery of similar bodies in its neighborhood that Pluto's gravity does not dominate.