1. Light: The sun is our primary source of light, making life on Earth possible. Plants use sunlight for photosynthesis, the process that creates energy for them (and ultimately for us). Sunlight also helps regulate our biological clocks and affects our moods.

2. Heat: The sun's energy warms the Earth, creating the temperatures necessary for liquid water and a diverse range of ecosystems. Without the sun's heat, Earth would be a frozen wasteland.

3. Energy: Sunlight is the ultimate source of energy for most life on Earth. Plants capture sunlight and convert it into chemical energy through photosynthesis. This energy is then passed on through food chains to all other living organisms.