Add Yahoo as a preferred source to see more of our stories on Google. On January 5, 2005, astronomers at NASA discovered Eris, the second-largest dwarf planet in the solar system. Eris is just ...

Pluto will complete its first orbit since 1930 in 2178, a historic 248-year space journey that spans generations of humans.

Scientists who argue for Pluto to be classified as a planet are getting more ammo for a debate that has raged over the last 15 years. A team of researchers published a study in the scientific journal ...

Why does Pluto's orbit take so long? Pluto's orbit is not like those of the eight major planets, which are relatively circular. Instead, it is highly elliptical and tilted. At tim ...

Add Yahoo as a preferred source to see more of our stories on Google. When you buy through links on our articles, Future and its syndication partners may earn a commission. Credit: NASA/Johns Hopkins ...

Pluto has not completed a single orbit since its 1930 discovery. With a 248-year journey around the Sun, the dwarf planet ...

Hundreds of people who love the little planet that was dissed, gather every year in the Arizona town where Pluto was ...

(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 ...

The science community may be ecstatic over the discovery of a ninth planet, but the former planet "Pluto" had a totally different reaction. Hours after scientists announced there's solid evidence of ...

It's going on two years since the International Astronomical Union rewrote its definition of a planet and busted Pluto down to something it called a "dwarf planet." But it's not a done deal, says Mark ...

Pluto may no longer be classified as a planet, but in Flagstaff, its legacy still shines. Scientists, artists and community ...