New Horizons / NASA
Image of Pluto sent by New Horizons in July 2015.
“Make Pluto a planet again”: NASA may reopen debate about the status of the “ugly duckling” of the Solar System — the only one discovered by an American.
The discussion about the status of , removed from the list of planets in the Solar System almost two decades ago, gained strength again after Jared Isaacmanhead of NASA, admitted that the North American space agency may revisit the topic.
The decision is far from consensual: the scientific community remains deeply divided over the classification of the small icy world, recalls .
Pluto was discovered on February 18, 1930 by American astronomer Clyde Tombaugh, at the Lowell Observatory in Arizona. For 76 years it was recognized as the ninth planet in the Solar System, the smallest and most distant. But, in 2006, the International Astronomical Union redefined the criteria for a celestial body to be considered a planet.
According to this definition, a planet must orbit the Sun, be approximately spherical in shape and be dominant in its orbit. Pluto meets the first two requirements but fails the thirdas it shares its orbital region with other icy bodies in the Kuiper Belt. Therefore, it was reclassified as dwarf planet.
The decision was controversial from the start. For many, Pluto’s exclusion seemed arbitrary, especially because planets like Earth and Jupiter also share orbital zones with asteroids.
Among the main defenders of restoring planet status is Alan Sternplanetary scientist and central figure of the New Horizons mission. Stern has been critical of the International Astronomical Union’s vote, arguing that science should not be decided by suffrage. The passage of the New Horizons probe by Pluto, in July 2015, reinforced the campaign: the images revealed a geologically complex world, with mountains, nitrogen glaciers and unexpectedly varied landscapes.
Still, the discovery was not enough to change the official classification. Now, Isaacman stated before a North American Senate committee that he would very much like to make Pluto a planet again and indicated that NASA is preparing work on the topic.
