She was married to Uranus. The Earth is the biggest of all the terrestrial planets. A terrestrial planet is a dense planet found in the inner Solar System. Our planet is an oasis of life in an otherwise desolate universe. The Earth's temperature, weather, atmosphere and many other factors are just right to keep us alive.
Scientists use the Earth to study all the other planets.
Since no human has ever visited another planet, we have to use what we know about the Earth, and try to guess what the other planets must be like. This is called Comparative Planetology.