Journey beyond Neptune to uncover the frozen, mysterious worlds that challenge everything we thought we knew about the solar ...

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 ...

When you buy through links on our articles, Future and its syndication partners may earn a commission. An illustration of confirmed dwarf planets and their moons. From left to right: Pluto (with ...

Pluto, discovered in 1930, was once considered the ninth planet in our solar system. In 2006, the International Astronomical Union reclassified Pluto as a dwarf planet because it doesn't meet all the ...

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, ...

The historic Lowell Observatory announced this week that it will drastically reduce internally funded research and shrink its ...

(Correction: An earlier version of this story misstated how far Pluto is from the sun. The correct number is 3.7 billion miles.) What was discovered in Flagstaff, Arizona, and killed off in Prague? If ...

Is a sun a star or a planet? While science now agrees the sun is a star, new telescopes may soon challenge how we define ...