sun
Give an example of how matter cycles. While matter cycles round and round in the Earth System, ENERGY FLOWS through the Earth System. The vast majority of Earths energy comes from the sun, flows into the Earths System, and flows out of the Earths System into space. If all the energy that comes to Earth from the sun were to stay on Earth, the Earth would melt away. But the energy that comes to Earth from the sun does not stay. Eventually it radiates back out to space as heat. We know this because the average temperature of the Earth has remained relatively constant. If the energy from the sun were to stay on Earth, the Earths average temperature would rise. Some of the suns energy is reflected by the atmosphere, some is absorbed by the Earth and re-radiated as heat, some evaporates water and powers the water cycle, some is captured by plants and used to make sugars, and some powers the wind but eventually ALL of the energy that comes to the Earth from the sun leaves the Earth and flows into space. For this reason we say that energy flows through the Earth System.