# Luminosity

Stars, galaxies and other objects emit energy in the form of radiation. It is measured in joules per second, which are equal to watts. A watt is one unit of power. Just as a light bulb is measured in watts, the Sun can also be measured in watts. The sun gives off 3.846×1026 W. This amount of power is known as 1 sol, the symbol for which is ${\displaystyle L_{\odot }}$.