Scientists have discovered a vast donut-shaped structure hidden within Earth which could hold the secret to why life was able to form on our planet.

Plate tectonics give Earth its mountains, earthquakes, continental drift and maybe even helped give rise to life itself. But do other planets in the solar system have them too?

The world’s mass and size suggest it is either a large rocky planet, known as a super-Earth, or a small gas giant, called a sub-Neptune, in the process of formation. We think Earth took between ...