Size alone doesn't bestow planethood. Moons of Jupiter and Saturn are wider than Mercury, and Pluto is smaller than Earth's moon. For years, astronomers tried to define a planet by shape ...

According to the new study, Sputnik Planitia was formed due to a collision with a planetary body, roughly twice the size of Switzerland from east to west, that likely crashed into Pluto at a ...

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 ...

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 ...

In contrast, Pluto's moon Charon has an estimated diameter of 744 miles (1,200 km). But the object could be smaller if it reflects more light than anticipated. One alternative measurement places ...