Once the quirky underdog of our solar system, Pluto held planetary status until 2006, when it got a cosmic demotion that still stings space fans. Discovered in 1930, Pluto was the ninth planet for ...

The debate over Pluto’s planetary status has been ongoing since its reclassification as a “dwarf planet” in 2006 by the International Astronomical Union (IAU). Recent discussions and new scientific ...

Before Pluto was discovered, it was predicted. Astronomers had observed that massive objects can affect the orbits of their neighbors and, after seeing deviations in the orbits of Uranus and Neptune, ...

Pluto, discovered 90 years ago on Feb. 18, 1930, was long considered the solar system's ninth planet. Although small, it orbits the sun and has the spherical shape required to be considered a planet.

Astronomers have identified a small but significant possibility that a Neptune-sized planet is quietly orbiting within the distant Oort cloud, the icy boundary of our solar system. According to recent ...

No longer a planet but not forgotten, Pluto’s colors, captured by NASA almost 10 years ago, continue to dazzle among the collection of colorful celestial objects only seen in the solar system. Since ...

The director of the American Museum of Natural History's Hayden Planetarium and author of The Pluto Files, Neil deGrasse Tyson, talks about the... Astrophysicist Tyson On 'Pluto Files' The director of ...

Earth has a newly-discovered neighbor in the solar system. But the heavenly body – possibly a dwarf planet à la Pluto – isn't a frequent visitor. Located beyond Neptune, its extreme orbit ...