Power of Sun

  • The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields.It has a diameter of about 1,392,000 km, about 109 times that of Earth, and its mass (about 2×1030 kilograms, 330,000 times that of Earth) accounts for about 99.86% of the total mass of the Solar System. Chemically, about three quarters of the Sun’s mass consists of hydrogen, while the rest is mostly helium.

    The remainder – about 1.69%, which nonetheless equals 5,628 times the mass of Earth – consists of heavier elements, including oxygen, carbon, neon and iron, among others.

    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 1,368 W/m2 (watts per square meter) at a distance of one astronomical unit (AU) from the Sun (that is, on or near Earth). Sunlight on the surface of Earth is attenuated by the Earth’s atmosphere so that less power arrives at the surface – closer to 1,000 W/m2 in clear conditions when the Sun is near the zenith.

    Solar energy can be harnessed by a 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, sometimes employing concentrating solar power – that it is measured in suns. The energy stored in petroleum and other fossil fuels was originally converted from sunlight by photosynthesis in the distant past.