The primary source of energy for life on Earth is the Sun. Solar energy is harnessed by plants through the process of photosynthesis, where they convert sunlight into chemical energy stored in glucose. This energy forms the base of the food chain and supports nearly all life forms on the planet. Herbivores consume plants to obtain energy, while carnivores eat herbivores and other animals, creating a complex web of energy flow. Without solar energy, life as we know it would not be sustainable, highlighting the crucial role of the Sun in Earth's ecosystems.