Introduction

All stars can, to a first approximation, be thought of as blackbodies. Blackbodies are objects which absorb and emit all wavelengths of light. However, depending on the temperature of the surface of the star, some wavelengths are emitted more strongly than others. For example, the Sun emits a lot of visible light and UV radiation and much less of gamma rays and radio waves.

To understand how to calculate the radiation produced by a star, we will begin at the turn of the 20th century.