The major source of energy for Earth's ecosystems is the Sun. Solar energy drives the process of photosynthesis, where producers capture sunlight to convert carbon dioxide and water into glucose and oxygen, forming the basis of food chains. This energy flow supports primary producers, herbivores, and consequently higher trophic levels. The Sun's energy also influences climate patterns and seasonal changes, playing a critical role in maintaining the balance and productivity of various ecosystems. Its importance is underscored by its role in sustaining life on Earth.