Where do we begin? Where does the human body truly begin—and where does it end? Ninety-three million miles away, the Sun casts its golden light upon us. That light, born in the heart of a star, travels across space to touch our skin, triggering the creation of nutrients within us. It enters the leaves of green plants, which produce the oxygen we breathe. In turn, we exhale carbon dioxide—what the plants take in. The Sun heats our oceans, driving evaporation that becomes clo