The number of planets that orbit the sun depends on what you mean by “planet,” and that’s not so easy to define ...

Charon is the largest moon of the dwarf planet Pluto, but calling it a moon ... Pluto has a mass of 1.3 x 10 22 kilograms and a diameter of 1,477 miles (2,377 kilometers), whereas Charon has ...

When we first began searching for planets around other stars, one of the surprising discoveries was that there are planets orbiting white dwarfs. The first exoplanets we ever discovered were white ...