# Luminosity

In astronomy, the total amount of energy emitted by a star or other astronomical object is its luminosity. It is measured in joules per second, which are watts. A watt is one unit of power. Just as a light bulb is measured in watts, so too is the Sun. The sun gives off 3.846×1026 W. This number is known as 1 sol, the symbol for which is $L_\odot$.