Pluto was once the ninth planet of our Solar System, but on August 24, 2006, that changed. The International Astronomical Union reclassified Pluto as a dwarf planet after introducing a new definition ...

For 76 years, generations of students learned that our solar system had nine planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto. Now, in 2026, some still can't get over ...

Twenty years after Pluto became a dwarf planet, people are still fighting over its status. Experts explain why the debate feels so personal.

Back in 2006, the International Astronomical Union determined that the definition of a planet is one where a body must “clear” its orbit. This means to be classed as a planet the object must be the ...

It was 20 years ago that our solar system lost a planet. Well, it didn't really go anywhere, but Pluto is no longer a planet because it's been reclassified. I'm sure you figured out in school that ...

Pluto was downgraded from a planet to a dwarf planet in 2006 by the International Astronomical Union. The main reason for Pluto's demotion is that it's not able to "clear its orbit of debris." Other ...

Twenty years after Pluto lost its planetary status, the debate continues as scientists still disagree over what defines a planet.