The definition of a planet has three requirements: first, it is in orbit around the sun; second, it has enough mass to make its surface reach a hydrostatic equilibrium shape (nearly spherical); and finally, it has been cleared. area near its orbit. Only eight planets discovered before 1900 met these requirements.

Relative to the deficiencies in the voting procedures, the most unacceptable thing among the scientists participating in the petition is the new planet definition. Regarding the second article of the definition of planet, the petitioning astronomers believe that the new definition uses dynamics rather than the characteristics of the material itself. This characteristic is a necessary condition for determining whether it can become a planet. And this result will affect the definition of other systems in astronomy, such as stars, galaxies, nebulae and even asteroids. Because dynamics are not the decisive factor in the definition of these systems.

According to the third requirement of the new planet definition, the earth may also be expelled.

These astronomers pointed out that if the third article of the new definition is followed, then planets like the Earth and Jupiter will not meet the definition and will also be "expelled". The third new definition says that a planet must have enough gravity to clear the area around its orbit. If we follow this definition, there are many asteroids between the orbits of Earth, Saturn, and Jupiter, so they cannot be considered to "clear the area near the orbit."

In addition to the astronomers who signed the petition, Williams University astronomer Jay Pasakoff, who participated in the voting meeting, also still insists that Pluto is a planet. He said: "The spirit of this meeting is to regulate future scientific discoveries and behaviors, but it should not be a denial of the past."

Many astronomers said that what they hope is to add new planets, Rather than ruling out Pluto.

Planet