Pluto Is Back!

Fans of the d-d-dwarf planet (yes, it’s still hard to say) Pluto can rejoice at the news of a small victory for the formerly ninth planet of our solar system.

In 2006, the International Astronomical Union issued its new definition of a planet and Pluto failed the third test – “clearing the neighborhood around its orbit” by becoming the dominant gravitational force in the area. After being reclassified as a d-d-dwarf planet, Pluto suffered the further indignity of being designated the second-largest of these behind the newly-discovered tenth planet wannabe, Eris.

Pluto supporters did not give up. In 2010, measurements taken during a stellar occultation showed Eris has a diameter of 2,326 km, much closer to the size of Pluto than first thought. Now, a report in the latest edition of the journal Icarus reveals that methane gas analysis of Pluto puts its diameter at 2368 km, moving it ahead of Eris as the largest d-d-dwarf planet and returning champion of the Edgeworth-Kuiper belt.

Eris supporters (all three of you) point out that the size battle with Pluto won’t be settled until July 2015, when the New Horizons spacecraft of NASA’s Pluto-Kuiper Belt mission passes Pluto and takes an accurate measurement.

In the meantime, let’s all say it together: Pluto rocks!