The controversy over whether Pluto is a planet has flared anew thanks to NASA Administrator Jim Bridenstine. The dust-up also involves a guitarist for “Queen,” who happens to have a Ph.D in astrophysics, and Alan Stern, the greatest living expert on the former ninth planet.
He committed what some considered science heresy while touring an engineering science building at the University of Colorado at Boulder, saying, “Just so you know, in my view, Pluto is a planet. You can write that the NASA administrator declared Pluto a planet once again. I’m sticking by that — it’s the way I learned it and I’m committed to it.”
Bridenstine is on to something that has bothered many people, including scientists, ever since Pluto was demoted to a “dwarf planet.”
While some witnesses think that Bridenstine was having some fun, the statement triggered some in the media. One story declared in its headline, “Trump’s NASA chief, who has no scientific background, says Pluto is a planet.”
The headline was an attempt to revive an old controversy surrounding Bridenstine from his confirmation hearings. Bridenstine is a Navy veteran whose academic training is in business and economics. He is not an engineer, scientist, or even a former astronaut. Thus, many in the media think he should stay in his lane. The scientific community has got this.
The problem is that when the International Astronomical Union downgraded Pluto as a planet, the action seemed arbitrary and presumptuous. In 2006, the IAU noted that the Kuiper Belt contains many thousands of objects, some of which are of similar size to Pluto. The question arose whether those new objects were also planets or whether the definition of a planet needed reclassification. The IAU choose the latter course.
The IAU developed a new definition of a planet. It is “A celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighborhood around its orbit.”
Since Pluto did not meet the third criteria it was suddenly not a planet any longer. Between 1930, when Clyde Tombaugh first discovered Pluto, and 2006, the solar system had nine planets. After 2006, eight planets are in orbit around the Sun.
Understandably, the new definition did not sit well with many in the scientific community. Who gave the IAU the authority to sweep away over 75 years of consensus about the proper classification of Pluto?
Dr. Alan Stern, a planetary scientist at the Southwest Research Institute in Boulder, Colorado is the chief among the Pluto as a planet advocates. Stern is the principle investigator of NASA’s New Horizons mission that flew by Pluto in 2015 and is currently exploring the Kuiper Belt. He is the greatest living expert on Pluto.
Stern dismisses the third criteria of the definition of a planet offered by the IAU. He suggests a more astrophysical definition. “According to this definition, a planet is a substellar object that has never undergone nuclear fusion and is rounded by its own gravity, regardless of its orbital parameters.” The Stern definition would expand the number of planets in the solar system from the current eight to roughly 100.
Stern could also bring the findings of the New Horizon to ram home his point. Rather than being an inert rock, like virtually every object in the Kuiper Belt. Pluto is a strange world with nitrogen ice glaciers and huge mountains supported by bedrock made of water ice. Some scientists even think that Pluto has a subsurface ocean, similar to those that reside beneath the surfaces of Europa, a moon of Jupiter, and Enceladus, a moon of Saturn.
Brian May joined in the reheated controversy in support of the position taken by Stern and Bridenstine. May is a guitarist for the band Queen. He also holds a Ph.D in astrophysics. May offered a “geographic” (astrographic?) definition of a planet on an Instagram post. “We can easily choose to make Pluto the outer edge of the classical planet zone, in which case we’ll end up with 9 planets and an ever-increasing number of Kuiper Belt Objects great and small, as they are discovered. Anybody like my definition ? It would have saved a lot of trouble 10 years ago !!”
The reason why this controversy matters, besides questions of ego and tradition, is that the way science classifies things matters. Whether Pluto is a planet or a “dwarf planet” will define how scientists treat it from now on.
Mark Whittington (@MarkWhittington) is the author of Why is It So Hard to Go Back to the Moon? and The Moon, Mars and Beyond. He also operates his own blog, Curmudgeons Corner.
The views and opinions expressed in this commentary are those of the author and do not reflect the official position of The Daily Caller.