Before 2006, people believed that there were nine planets in the solar system. That year, the astronomical community made a controversial decision to reduce the number of officially recognized planets to eight—Pluto was excluded. According to "Nature", recently, NASA Administrator Jared Isaacman stated at a hearing in the U.S. Senate that he firmly supports the restoration of Pluto's deprived planet status, and said that NASA is "currently writing documents and preparing to promote a re-examination of this issue in the scientific community."

Isaacman’s remarks sparked debate among researchers, with some supporting the proposal and others firmly opposed.

“The question of whether we should call Pluto a planet distracts from the real scientific issues,” said Amanda Hendrix, a researcher at the U.S. Planetary Science Institute.

What really angered some astronomers was that Isaacman expressed support for the administration’s proposal to cut NASA’s science budget in half at this hearing. Coupled with budget cuts at the National Science Foundation, many astronomers feel the research field is under siege. “It’s crazy to ‘make Pluto a planet again’ while ruining the careers of those of us who study Pluto,” planetary scientist Adeene Denton wrote on social media.

David Grinspoon, an astrobiologist at the Planetary Science Institute, is one of those who has opposed Pluto's downgrade from the beginning until now. He advocated reopening the discussion, but believed that NASA's involvement in the matter could be counterproductive because this should be a decision made at the international level. What kind of celestial body is considered a planet? The real authority to explain what kind of celestial body is a planet lies with the International Astronomical Union (IAU). This agency is responsible for establishing official astronomical terminology.

“Even though I would ultimately like to see a better definition that is widely accepted, it’s not up to NASA to announce it,” Grinspoon said.

The original rationale for reclassifying Pluto was the discovery of other similarly sized objects in the solar system. Some objects, such as Eris, which was discovered in 2004, are more massive than Pluto and are at least as qualified as Pluto to be called planets. It is estimated that there may be hundreds or even thousands of Pluto-sized objects in the solar system, although in many cases the properties of these objects are unknown.

In 2006, after a fierce debate, the IAU believed that in order for a celestial body to become a planet, it must meet three conditions: maintaining an approximately spherical shape in hydrostatic equilibrium; orbiting the sun; and clearing celestial bodies in the vicinity of the orbit. Pluto failed to meet the third condition and was classified as a "dwarf planet."

"Many of us believe that the word 'planet' should be defined in terms of the intrinsic properties of the celestial body itself, rather than its dynamic environment. If the Earth was suddenly surrounded by a group of small celestial bodies, as it was for its first few hundred million years, would it cease to be a planet? That seems absurd," Grinspoon said.

Kelsi Singer, project scientist for NASA's New Horizons spacecraft, said the initial debate served no purpose other than unproductive distractions. "New Horizons" has provided a lot of information for mankind to understand Pluto.

Singer believes that forcing people to take sides "creates unnecessary tension within the scientific community." She added that there are still some in the planetary science community who feel strongly that Pluto should be called a planet. "NASA makes a statement that has a big impact."