Back in 2006, a science organization changed the classification of Pluto as a planet, sparking a debate in both the astronomical community and pop culture. More than 15 years later, a new paper is reigniting that debate.

The International Astronomical Union is responsible for classifying and naming celestial bodies. By changing the definition of planet back in 2006, the organization essentially downgraded Pluto from planet to dwarf planet.

Florida Space Institute planetary scientist Philip Metzger co-authored a new paper taking a fresh look at the decision — and he’s urging the IAU to reconsider its definition.

The story of the IAU’s decision reads like a political thriller and dates back more than 100 years of planetary history. Metzger joins the show to talk about the secrecy, intrigue and historical context of Pluto’s planethood and why the IAU’s decision matters to science.

This episode was produced with assistance from WMFE intern Beatriz Oliveira.