How can spectra tell us what things are made of?

Stars and planets are too far away for a human to touch, yet we know what they are made of. Spectra make this possible! Let’s investigate how.

Atoms and Spectra

Atoms can interact with light in different ways. So far, we have explored how atoms emit light at specific wavelengths, as with hydrogen in the top panel.

The spectrum in the bottom panel results from a different type of interaction between atoms and light.

Spectrum Tool. Examine these two spectra.

  1. What do the hydrogen emission spectrum and the comparison spectrum have in common? In what ways are they different?

Spectrum Notebook. Write your answers in the Atoms and Spectra section.

Source 1:
Atoms and Molecules — Hydrogen Emission
Brightness
Full-intensity spectrum backgroundTransparency increases or decreases based on chart intensity, hiding or revealing the background
Left axis ticks
Spectrum intensity vs wavelength chart
Bottom axis ticks
Wavelength (Microns)
Source 2:
Atoms and Molecules — Comparison Spectrum
Brightness
Full-intensity spectrum backgroundTransparency increases or decreases based on chart intensity, hiding or revealing the background
Left axis ticks
Spectrum intensity vs wavelength chart
Bottom axis ticks
Wavelength (Microns)
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