The electromagnetic spectrum includes a range of all types of light , not just what we can see. So, the electromagnetic spectrum is the term scientists use to describe the entire range of light that exists. Our eyes see visible lightThe electromagnetic waves your eyes detect – visible light – oscillate between 400 and 790 terahertz (THz). The coolest part of the electromagnetic spectrumAstronomers use the entire electromagnetic spectrum to observe a variety of things. Most stars emit visible lightThe majority of stars emit most of their electromagnetic energy as visible light, the tiny portion of the spectrum to which our eyes are sensitive.