For decades, our solar system was thought to have nine planets, with Pluto considered the smallest and farthest. But in 2006, Pluto was officially reclassified as a dwarf planet by the International ...

On August 24, 2006, our solar system lost a planet. It wasn't by cataclysmic destruction, but rather by the vote of the International Astronomical Union, which declared that Pluto, considered the ...

Alfredo has a PhD in Astrophysics and a Master's in Quantum Fields and Fundamental Forces from Imperial College London.View full profile Alfredo has a PhD in Astrophysics and a Master's in Quantum ...

Scientists think there may be a ninth planet hiding in the distant reaches of the solar system — and a new telescope could finally prove its existence. | Credit: Nicholas Forder for Live Science Deep ...

A fresh study of the Kuiper Belt’s structure has revived that far-out question, pointing to a possible Earth-sized ...

A giant planet similar to Uranus or Neptune may orbit the sun in the solar system's outer reaches. "Planet Nine" is shown here in an artist's impression that includes hypothetical lightning on the ...

A newly discovered warp in the outer Solar System may have been created by a small, rocky world, much closer to the Sun than ...

Arizona Governor Katie Hobbs signed a law making Pluto the state's official planet. That's even though an international group of scientists stripped Pluto of its planetary status back in 2006, ...

As the world marvels at the first-ever close-up images of Pluto beamed to Earth, it is a reminder of a sharp global division: those with nine-planet childhoods vs. those now growing up in a solar ...

When I was a kid, there were nine planets. Now we know of thousands! But that includes exoplanets, alien worlds that orbit alien suns. Only eight planets call our solar system home. Or there might ...