Imagine a healthy planet with healthy humans living on it: the world has embarked on a path to clean energy, clean air and fresh water; we are feeding ourselves without compromising land or sea ...

Our planet orbits 93 million miles (150,000 km) away from the sun. This puts Earth in a so-called "Goldilocks zone," where the temperature is just right for liquid water to exist on the surface.

When Earth first formed, it was too hot to retain ice. This means all the water on our planet must have originated from extraterrestrial sources. Studies of ancient terrestrial rocks suggest ...