Many Factors Combine to Allow Life on Earth

As we look at planet Earth and the factors that enabled us to be here, we quickly realize that our planet is very special. Here’s a short list: the long-term existence of a protective and oxygen-rich atmosphere; Earth’s axial tilt, stabilized by a single large moon; the ozone layer and the magnetic field, which jointly protect surface creatures from lethal cosmic radiation; plate tectonics, which regulates the levels of carbon dioxide and keeps the global temperature stable; the fact that...