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The orbit is cluttered—it's a dwarf. Where's the justice?
Pluto has once again drawn NASA into a dispute that astronomers have been unable to resolve since 2006. At a US Senate hearing, NASA Administrator Jared Isaacman supported the idea of reinstating Pluto's planet status and announced that NASA is preparing scientific materials for discussion with researchers. However, reinstating Pluto as a planet is not possible through presidential decree or agency action. Everything hinges on the definition of a planet, and astronomers still lack complete agreement on that.
Pluto was discovered in 1930, and for most of the 20th century, it was considered the ninth planet in the Solar System. School textbooks kept it simple: after Neptune came the small, distant Pluto. Then astronomers studied the outer Solar System more closely and found other icy bodies there, similar to Pluto in size, composition, and orbit. The old list no longer explained why Pluto should remain a planet while similar objects should not.
In 2006, the International Astronomical Union adopted a new definition of a planet. An object must orbit the Sun, have enough mass for its own gravity to shape it into a nearly spherical shape, and clear its orbital region of other bodies. Pluto meets the first two conditions, but fails the third: it orbits in the Kuiper Belt, where numerous icy bodies remain nearby. Following this, Pluto was reclassified as a dwarf planet.
The debate hasn't ended since then. Those who favor the former status believe Pluto is too complex a celestial body to be relegated to the background simply because of its orbit: it has an atmosphere, mountains, icy plains, traces of geological activity, and several moons. According to their logic, it's more important to look at the properties of the world itself, rather than how well it has cleared the space around its trajectory.
Opponents of Pluto's return respond differently. If the orbital criterion were removed, the number of planets in the Solar System would quickly increase. Beyond Neptune lie other large bodies, and some of them would also have to be included. Therefore, the Pluto question has long since transcended the realm of schoolboy nostalgia. Astronomers are debating not over sympathy for the small, icy world, but over the rules by which celestial bodies should be classified in general.
A new wave of discussion began after US President Donald Trump proposed returning Pluto to planet status by executive order. However, scientific classifications don't change that way. The International Astronomical Union approves the names of objects, as well as astronomical standards and definitions. A political statement may draw attention to the topic, but it doesn't change the status of a celestial body in professional astronomy.
Isaacman adopted a more cautious approach. He told senators that NASA is working on scientific papers and wants to present its position to experts for discussion. What new data the agency plans to present on Pluto remains unclear. NASA did not immediately provide further details when contacted by reporters.
At the same hearing, the NASA administrator also outlined other plans for the agency. The Nancy Grace Roman Space Telescope could launch a month ahead of its current schedule. The launch is currently expected in September, but Isaacman allowed for a delay to August. Roman is designed to study dark energy, exoplanets , and the large-scale structure of the Universe. For NASA, this telescope is also important as a tool for searching for worlds where signs of habitability could be sought in the future.
Roman won't act as a replacement for Hubble, but as an observatory with a much wider field of view. The telescope will be able to observe large swaths of the sky and collect statistics on a huge number of objects. This is especially important for exoplanet searches: scientists need to understand how often planets orbit different stars, what orbits they occupy, and where worlds with Earth-like conditions might be located.
Isaacman also confirmed plans for the Space Reactor-1 Freedom mission to Mars in 2028. The project is intended to be the first to test a nuclear fission reactor as a power source for an interplanetary spacecraft. For long-distance missions, this technology could offer greater potential than solar panels: the farther a spacecraft travels from the Sun, the less energy it receives from light.
But the hearing wasn't limited to Pluto, the telescope, and the Mars reactor. Senators congratulated NASA on the success of the Artemis II mission to the Moon and then moved on to the budget. Democrats asked Isaacman for his support for the Trump administration's proposal for the next fiscal year. The plan calls for a 46% cut in NASA's science program.
Pluto has once again drawn NASA into a dispute that astronomers have been unable to resolve since 2006. At a US Senate hearing, NASA Administrator Jared Isaacman supported the idea of reinstating Pluto's planet status and announced that NASA is preparing scientific materials for discussion with researchers. However, reinstating Pluto as a planet is not possible through presidential decree or agency action. Everything hinges on the definition of a planet, and astronomers still lack complete agreement on that.
Pluto was discovered in 1930, and for most of the 20th century, it was considered the ninth planet in the Solar System. School textbooks kept it simple: after Neptune came the small, distant Pluto. Then astronomers studied the outer Solar System more closely and found other icy bodies there, similar to Pluto in size, composition, and orbit. The old list no longer explained why Pluto should remain a planet while similar objects should not.
In 2006, the International Astronomical Union adopted a new definition of a planet. An object must orbit the Sun, have enough mass for its own gravity to shape it into a nearly spherical shape, and clear its orbital region of other bodies. Pluto meets the first two conditions, but fails the third: it orbits in the Kuiper Belt, where numerous icy bodies remain nearby. Following this, Pluto was reclassified as a dwarf planet.
The debate hasn't ended since then. Those who favor the former status believe Pluto is too complex a celestial body to be relegated to the background simply because of its orbit: it has an atmosphere, mountains, icy plains, traces of geological activity, and several moons. According to their logic, it's more important to look at the properties of the world itself, rather than how well it has cleared the space around its trajectory.
Opponents of Pluto's return respond differently. If the orbital criterion were removed, the number of planets in the Solar System would quickly increase. Beyond Neptune lie other large bodies, and some of them would also have to be included. Therefore, the Pluto question has long since transcended the realm of schoolboy nostalgia. Astronomers are debating not over sympathy for the small, icy world, but over the rules by which celestial bodies should be classified in general.
A new wave of discussion began after US President Donald Trump proposed returning Pluto to planet status by executive order. However, scientific classifications don't change that way. The International Astronomical Union approves the names of objects, as well as astronomical standards and definitions. A political statement may draw attention to the topic, but it doesn't change the status of a celestial body in professional astronomy.
Isaacman adopted a more cautious approach. He told senators that NASA is working on scientific papers and wants to present its position to experts for discussion. What new data the agency plans to present on Pluto remains unclear. NASA did not immediately provide further details when contacted by reporters.
At the same hearing, the NASA administrator also outlined other plans for the agency. The Nancy Grace Roman Space Telescope could launch a month ahead of its current schedule. The launch is currently expected in September, but Isaacman allowed for a delay to August. Roman is designed to study dark energy, exoplanets , and the large-scale structure of the Universe. For NASA, this telescope is also important as a tool for searching for worlds where signs of habitability could be sought in the future.
Roman won't act as a replacement for Hubble, but as an observatory with a much wider field of view. The telescope will be able to observe large swaths of the sky and collect statistics on a huge number of objects. This is especially important for exoplanet searches: scientists need to understand how often planets orbit different stars, what orbits they occupy, and where worlds with Earth-like conditions might be located.
Isaacman also confirmed plans for the Space Reactor-1 Freedom mission to Mars in 2028. The project is intended to be the first to test a nuclear fission reactor as a power source for an interplanetary spacecraft. For long-distance missions, this technology could offer greater potential than solar panels: the farther a spacecraft travels from the Sun, the less energy it receives from light.
But the hearing wasn't limited to Pluto, the telescope, and the Mars reactor. Senators congratulated NASA on the success of the Artemis II mission to the Moon and then moved on to the budget. Democrats asked Isaacman for his support for the Trump administration's proposal for the next fiscal year. The plan calls for a 46% cut in NASA's science program.
