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

However, this year a powerful new telescope is coming online that could prove once and for all that there really is a ninth planet in our Solar System. The same year that Pluto was ignominiously ...

All seven of the other planets in our solar system are about to become visible at once in a great planetary alignment – ...

Plate tectonics give Earth its mountains, earthquakes, continental drift and maybe even helped give rise to life itself. But ...