Pluto's planetary status debate continues 20 years after demotion

Two Decades of Debate

Twenty years ago, the International Astronomical Union (IAU) voted to reclassify Pluto from a major planet to a dwarf planet. This decision, made in August 2006, reduced the number of major planets in our solar system from nine to eight. The reclassification sparked immediate controversy among scientists and the public, a debate that continues to be polarized today.

Critiques of the IAU Definition

Philip Metzger, director of the Stephen W Hawking Centre for Microgravity Research and Education, criticizes the IAU's definition of a planet, stating it is not useful in science. Metzger is among several scientists and individuals who believe Pluto's demotion was a mistake, arguing that the definition created by the IAU is impractical for scientific application.

Public and Scientific Advocacy

Pluto's downgraded status has garnered affection from many, with some viewing it as an 'underdog.' Kevin Schindler, historian at the Lowell Observatory where Pluto was discovered, notes this sentiment. Laurel Kornfeld, an amateur astronomer, became an advocate on the day of the vote, expressing that the decision was wrong. The campaign to reinstate Pluto, characterized by passionate advocates and occasional protests, is largely concentrated in the United States, partly due to Pluto's discovery by an American astronomer.

Political and Scientific Context

The debate has recently acquired a populist dimension, with figures like Jared Isaacman, Trump's Nasa administrator, publicly supporting a re-evaluation of Pluto's status. The original IAU vote was prompted by the discovery of Eris, a celestial body in the Kuiper Belt similar in size to Pluto. The question arose: if Pluto was a planet, then Eris should also be one, or if Eris was not, then Pluto's status needed reconsideration.