The Sun is the most prominent feature in our solar system.

The Sun has been active for 4.6 million years and has enough fuel to go on for another five million years or so. Energy is created deep within the core of the Sun and some is projected as Sunlight. Sunlight is Earth’s primary source of energy.

The solar constant is the amount of power that the Sun deposits per unit area that is directly exposed to sunlight. The solar constant is equal to approximately 1368 watts per square meter at a distance of one AU from the Sun (that is, on or near Earth).

Sunlight on the surface of Earth is attenuated by the Earth’s atmosphere and this means that not all power arrives at the surface - closer to 1,000 watts per square meter actually arrives on areas of the surface directly exposed in clear conditions when the Sun is near the zenith. This energy can be harnessed via variety of natural and synthetic processes – photosynthesis by plants captures the energy of sunlight and converts it to chemical form (oxygen and reduced carbon compounds), while direct heating or electrical conversion by solar cells are used by solar power equipment to generate electricity or to do other useful work. The energy stored in petroleum and other fossil fuels was originally converted from sunlight photosynthesis in the distant past.