PPT Slide
We plot spectra as graphs: graphs showing precisely how much power the thing we are looking at emits at each precise wavelength.
Spectra are incredibly useful. Luckily, all chemicals emit and absorb light at certain very specific wavelengths. A typical spectrum (like this spectrum of gas spiraling into a black hole) can be used to identify the composition of the gas.
To an expert (like me), every bump and wiggle in a spectrum like this tells a story of what the gas is made of, how it’s moving, and how hot it is.
Strength of light at this wavelength