Answer:
One major change that has happened to Earth over the past 4.6 billion years is the development of the atmosphere. Over time, the atmosphere has gone through several stages of development, including the formation of an oxygen-rich atmosphere, the development of the ozone layer, and the evolution of life. Initially, the atmosphere was composed of simple gases like hydrogen and helium, but as the Earth cooled, heavier molecules such as nitrogen and carbon dioxide were added. As life evolved, photosynthetic organisms began to produce oxygen, which increased the amount of oxygen in the atmosphere. This allowed for the formation of the ozone layer, a protective shield that blocks out harmful UV radiation from the Sun. The presence of the ozone layer allowed for the development of complex life forms on Earth. The driving force behind the development of the atmosphere was the energy from the Sun, which provided the energy needed for the formation of the atmosphere and the evolution of life.