What is the main source of energy for Earth?

The Sun is the main source of energy for Earth as it provides the light and warmth necessary for life on the planet. Its energy drives photosynthesis in plants, which is fundamental for food production within ecosystems. Additionally, the Sun's energy influences weather patterns and climate, contributing to the various systems and processes that support life.

While the Earth's core is responsible for geothermal heat, this energy source is relatively small compared to the energy received from the Sun. The Moon does influence certain Earth processes such as tides but does not provide energy in the same way the Sun does. Geothermal vents also contribute some heat to specific ecosystems, particularly in ocean depths, but again, this is a fraction of the energy supplied by the Sun. Hence, the Sun's role as the primary energy source is essential for sustaining life and maintaining the environmental systems on Earth.