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.

Wavelength (nm)

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

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