Hello. In most texts I have read, EM radiation is depicted as sinusoidal in shape. I understand why this would be the case, as the oscillating fields are often the product of circular generators or alternating current, but is this always the case? For example, is the light we receive from stars sinusoidal as well? If so, why? Same with other sources of natural E&M, like atomic transitions that produce color. I'm sure there is a very simple answer, but please help me understand this. Thank you.