The International Astronomical Union (IAU) defined a dwarf planet in 2006 as a celestial body that orbits the Sun, is round in shape, but has not cleared its orbital neighborhood of objects of ...

Everything you know about Pluto is probably wrong. Just ask a kid. Kids are much more up-to-date with knowledge about space and dinosaurs and other cool stuff we grown-ups haven’t read about in … well ...

Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto. Many Americans grew up with this as the definitive planetary lineup and created clever mnemonic devices to memorize them in ...

Pluto has long been one of the most debated celestial bodies in our solar system. Once classified as the ninth planet, it was redefined in 2006 as a dwarf planet, a decision that still sparks ...

When the International Astronomical Union (IAU) demoted Pluto from a planet to a dwarf planet in 2006, it surprised a lot of people, including some scientists. Even many years later, some astronomers ...

This story is part of Short Wave's series Space Camp about all the weird, wonderful things happening in the universe. Check out the rest of the series. If you were born in the last century you might ...

The controversy endures over Pluto's true status, but the solar system underdog continues to capture hearts across the globe. When you purchase through links on our site, we may earn an affiliate ...

Astronomers recently discovered two more moons orbiting Pluto in addition to its already-discovered moon, Charon. Madeleine Brand talks with Ira Flatow, host of NPR's Talk of the Nation Science Friday ...

Editor’s note: A version of this story originally appeared in Astronomy’s 2007 special issue 50 Greatest Mysteries of the Universe. For a more recent discussion of Pluto’s planethood, see “An ...