Planetary scientist Paul Byrne believes Pluto should be called a planet
Twenty years after the International Astronomical Union’s decision to reclassify Pluto as a dwarf planet, Washington University in St. Louis planetary scientist Paul Byrne believes it should be called a planet. In his view, this definition should also apply to other dwarf planets — Ceres, Eris, Makemake and Haumea, Space.com reports.
The 2006 decision
The International Astronomical Union adopted a new definition of a planet in August 2006. It requires a celestial body to be nearly spherical under its own gravity, orbit the Sun, and clear the neighborhood of its orbit of other objects.
Pluto does not meet the third criterion: its orbit intersects with Neptune’s orbit, and other Kuiper Belt objects move nearby. The debate over Pluto’s status intensified after the 2005 discovery of Eris, a body comparable in size to Pluto and located farther from the Sun. During the union’s meeting, various options were considered, some of which envisaged recognizing up to 14 planets in the Solar System, but Pluto was ultimately classified as a dwarf planet.
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Paul Byrne’s approach
Byrne proposes primarily assessing the geophysical properties of celestial bodies. In his view, objects whose gravity has given them a spherical shape and caused internal differentiation of matter may have planetary processes, including the formation of an atmosphere, volcanism, changes in terrain, or a magnetic field. Under this approach, Pluto has grounds to be considered a planet.
The New Horizons mission, which reached Pluto in 2015, showed that it is a complex world with active nitrogen glaciers and a large heart-shaped structure on its surface. At the same time, Byrne acknowledges that the dispute largely concerns terminology. Models of Solar System formation allow for the existence of hundreds of as-yet undiscovered bodies similar to Pluto and Eris in the scattered disc and the Oort Cloud.
