{"id":556352,"date":"2026-05-05T15:56:05","date_gmt":"2026-05-05T15:56:05","guid":{"rendered":"https:\/\/winklersart.com\/?p=556352"},"modified":"2026-05-05T15:56:05","modified_gmt":"2026-05-05T15:56:05","slug":"could-pluto-once-again-be-considered-a-planet-new-remarks-from-nasas-administrator-highlight-an-enduring-debate-among-scientists","status":"publish","type":"post","link":"https:\/\/winklersart.com\/?p=556352","title":{"rendered":"Could Pluto Once Again Be Considered a Planet? New Remarks From NASA’s Administrator Highlight an Enduring Debate Among Scientists"},"content":{"rendered":"
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Two decades ago, the International Astronomical Union\u2014which defines and names celestial bodies\u2014redefined the criteria for being a planet, putting Pluto into the new category of dwarf planet<\/h2>\n
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Margherita Bassi<\/p>\n

| Daily Correspondent<\/span><\/p>\n

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Pluto was considered the solar system’s ninth planet for more than 70 years.
\n NASA \/ JHU-APL \/ SwRI<\/span>
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For decades, scientists and the general public have argued over the astronomical status of beloved dwarf planet Pluto. In the latest salvo, NASA Administrator Jared Isaacman said that he was \u201cvery much in the camp of \u2018make Pluto a planet again,\u2019\u201d during a Senate hearing on April 28.<\/p>\n

Isaacman\u2019s statement highlights the longstanding debate over Pluto\u2019s classification. His remarks were made during a hearing over the Trump Administration\u2019s proposed budget cuts to NASA.<\/p>\n

Pluto was discovered by American astronomer Clyde Tombaugh in 1930 at an observatory in Flagstaff, Arizona. Tombaugh, born in Illinois and raised in Kansas in a farming family, had a childhood fascination with space and was about to embark on career building telescopes when a magazine article about Mars alerted him to the scientists working at Lowell Observatory in Flagstaff. Within months after arriving, according to the Observatory, Tombaugh took over the search for \u201cPlanet X\u201d and found Pluto by examining photographic plates with a machine called a blink comparator.<\/p>\n

For more than 70 years, it was considered the solar system\u2019s ninth, most distant planet. In 2006, however, the International Astronomical Union (IAU)\u2014which defines and names celestial bodies\u2014announced a new definition for \u201cplanet\u201d that saw Pluto booted from the classification.<\/p>\n

\u201cI would say we are doing some papers right now on, I think, a position that we would love to escalate through the scientific community to revisit this discussion and ensure that Clyde Tombaugh gets the credit he received once and rightfully deserves to receive again,\u201d Isaacman said during the hearing.<\/p>\n

Davide Castelvecchi at Nature <\/em>reports that it\u2019s unclear which papers he was referencing, and NASA did not respond to the outlet\u2019s request for clarification. In a March interview with the Daily Mail\u2019s Charlie Spiering, Isaacman cited Pluto\u2019s uniquely American origins, saying, \u201cI think we owe it to everyone from Kansas and all their great contributions to astronomy and aerospace to rightfully restore that discovery to a planet.\u201d<\/p>\n

According to the IAU\u2019s 2006 decision, a celestial body must fulfill three criteria to be considered a planet: orbit the sun, have enough mass and gravity to pull itself into a round shape and clear the area surrounding its orbit from other debris.<\/p>\n

Pluto doesn\u2019t meet the last requirement, therefore putting it into the category of dwarf planet, a new class the organization established in 2006. Part of the ruling stemmed from the 2005 discovery of Eris, an astronomical body with more mass than Pluto, once poised to become the solar system\u2019s tenth planet. With the updated guidance, Eris was also dubbed a dwarf planet.<\/p>\n

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Did you know? NASA\u2019s Pluto flyby mission<\/p>\n

Earlier in 2006\u2014before the demotion\u2014NASA launched the New Horizons spacecraft to fly by Pluto. It reached the distant celestial body nearly ten years later and collected a trove of data about the icy world. It\u2019s the only probe ever to study the dwarf planet, and it\u2019s now hurtling toward interstellar space.<\/p>\n<\/p><\/div>\n<\/div>\n

The change was meant to reflect a modern understanding of planetary systems, but the IAU\u2019s decision was\u2014and still is\u2014contentious.<\/p>\n

\u201cMany of us feel that the word \u2018planet\u2019 should be defined by the intrinsic properties of a body, not by its dynamical environment,\u201d David Grinspoon, an astrobiologist at the Planetary Science Institute, tells Nature<\/em>. \u201cIf, suddenly, the Earth was surrounded by a swarm of small objects\u2014as it was for the first several hundred million years of its existence\u2014would it no longer be a planet? This seems silly.\u201d<\/p>\n

The definition of a planet could also be considered problematic in ways unrelated to Pluto. For example, the criterion of orbiting the sun\u2014which refers to just our solar system\u2019s star\u2014means the only official planets in the universe are Earth and its seven neighbors. All the others are technically exoplanets.<\/p>\n

\u201cIt\u2019s a sloppy definition,\u201d said Philip Metzger, a planetary scientist at the University of Central Florida, in a 2018 statement. \u201cThey didn\u2019t say what they meant by clearing their orbit. If you take that literally, then there are no planets, because no planet clears its orbit.\u201d<\/p>\n

Metzger led a review of scientific literature published over the past 200 years and found just one publication that included the orbit-clearing requirement when categorizing planets. He and his co-authors argue that the new definition is not supported by past research.<\/p>\n

In 2024, three planetary scientists proposed making the definition of \u201cplanet\u201d more quantifiable, arguing that a body is a planet if it orbits one or more stars, stellar remnants or brown dwarfs and has a mass between 1023<\/sup> kilograms, enough to clear its orbit of debris, and 2.5 x 1028<\/sup> kilograms, or 13 times the mass of Jupiter. Notably, Pluto is still not massive enough to meet these criteria.<\/p>\n

\u201cI believe that the decision taken [by the IAU] was the correct one,\u201d Catherine Cesarsky, an astronomer and IAU president from 2006 to 2009, told Science News\u2019 Lisa Grossman in 2021. \u201cPluto is very different from the eight solar system planets, and it would have been very difficult to keep changing the number of solar system planets as more massive [objects beyond Neptune] were being discovered.\u201d<\/p>\n