Although Earth and the Sun are separated by 150 million km, they are inextricably linked by an energy flow that both sustains and imperils life. A 15.8-million-K nuclear furnace in the innermost one-third of the Sun is the source of this energy, which photons, particles, and fields disseminate throughout the solar system. Figure 1 depicts major components of the Sun–Earth system, and figure 2 summarizes the energy flow.
Radiative and convective processes transfer energy from the Sun’s core to its surface, a gaseous shell that radiates electromagnetic energy primarily at visible wavelengths. Solar photons reach Earth in eight minutes, where most are absorbed and reflected near the surface. This dominant energy flow from the Sun’s surface to Earth’s enables life by heating our planet, fueling photo-synthesis, and powering the interactions among oceans, land, and atmosphere that generate weather and climate. 1
Encapsulating Earth’s thin life-sustaining surface region is an...
