GEF

Unit 4   |  The Global Ecosystem 89 Essential Concept Earth’s systems are connected and interdependent. 4.1  Our Planet in Context Let’s head to outer space and then work our way back to Earth. The universe can be defined as the sum of everything that exists, including space and matter. When astrophysicist Neil deGrasse Tyson was asked if the vastness of the universe makes him feel hopelessly small, he responded, “No, it makes me feel big because we are made of the same basic elements as our galaxy.” One important element for life is carbon formed from explod- ing stars. Carbon easily combines with other elements creating organic molecules . These molecules are the building blocks of all life, including humans. We are, literally, stardust. Tyson explains that we are both in the universe and the universe is in us: “We are all connected to each other biologically, to the Earth chemically, and to the rest of the universe atomically.” Carbon and water are the building blocks of life. ELEMENT A pure chemical substance containing one type of atom. MOLECULES Groups of two or more atoms held together by chemical bonds.