The Issue is NOT Just Planetary Status
I recently got into a fascinating late-evening computer chat with someone who is really incensed that Pluto is no longer a planet. He seemed pretty upset about it, and although not a planetary scientist, seemed cognizant of the IAU’s role in the supposed “demotion” of Pluto a few years ago. Since we just passed the anniversary of that silly vote that led to all the commotion, and in light of my conversational partner’s concerns about this distant world, I thought it a good time to talk about Pluto again.
Essentially, there are two issues: the definition of planet (and where Pluto fits) and the IAU vote. People get upset about the second issue without understanding the scientific implications of the first. And, whether or not the IAU voted the way it did, there was and is still a healthy conversation going on in the planetary science community about just how we define solar system objects, particularly planets.
In less than a year, we’ll know more about Pluto than at any other time in human history. The New Horizons spacecraft will have just completed a successful flyby of Pluto, looked at Charon (its companion), and its moons (and maybe will have found a few more!). It will be exciting, and as Alan Stern (PI of the New Horizons mission put it on a recent NASA press conference), ” A year from now, we’ll write the textbooks on Pluto.”