Pluto, once considered the ninth planet of our solar system, has been a topic of intrigue since its reclassification as a ...

Astronomers propose a new hypothetical planet, Planet Y, beyond Neptune, based on observed orbital anomalies in the Kuiper ...

With a diameter of 1,440 miles, Pluto is farthest from the sun. While major planets make roughly circular orbits, Pluto ...

On Aug. 24, 2006, the International Astronomical Union (IAU) decided that Pluto wasn't a planet anymore. Instead, Pluto is ...

Though Pluto has formally been considered a dwarf planet for almost two decades, it still has many lessons left for planetary scientists — including hints about how the solar system formed.

On July 14, 2015, NASA's New Horizons spacecraft arrived at Pluto for the first time. The craft flew within 7,700 miles of the planet and is sending back reams of data and the highest resolution ...