There have been many “Tenth planet discovered”-type headlines in the media recently. The “planet” in question, spied by NASA-funded researchers, has been unofficially named Sedna after the Inuit goddess of the sea. It is almost twice as far from the sun as Pluto and about two-thirds of its diameter.
Déja-vu anyone? Similarly ill-informed headlines were bandied around in 2002, with the discovery of Quaoar, another distant body orbiting the sun. Several other small bodies have been found and astronomers expect to find more, possibly one even larger than Pluto. Whether or not such objects can be called planets isn’t important, it just depends how you define the term. But if anything, Pluto’s status as a planet is beginning to look increasingly hard to justify. Perhaps it is just the closest of many small, distant iceballs.