Far from being flat and boring, Pluto seemed to be full of mountains, plains and maybe even "snow". By measuring the size of the shadows, we could estimate the height of these peaks at over 4,000m ...

What’s more, the glacier is pristine ... of 4.67 billion miles. That, plus Pluto’s small size—smaller than our moon—suggested ...

in diameter -- about one-fourth the size of the planet Pluto. The object is classified as a minor planet, like thousands of other asteroids and comets in our solar system. It is second in size ...

"Like Sedna, Gonggong also lacks surface methane," said Bettati. "Since Gonggong is similar in size to Sedna, we believe ...

A surprising chemical difference between Pluto and Sedna, another dwarf planet in the distant Kuiper Belt, is helping scientists nail down their respective masses, a new study reports. The Kuiper ...