The sun is considered as the major source of energy because it provides light and heat, which are essential for life on Earth. The sun's energy is harnessed through solar panels, which convert the sun's energy into electricity. This electricity can be used to power homes and businesses, reducing our reliance on fossil fuels and other non-renewable sources of energy. The sun also plays a role in the Earth's climate, as it provides the energy that drives the water cycle, which in turn affects weather patterns. Overall, the sun is a critical source of energy that is essential for life on Earth.