* Light from a star is a continuous spectrum: This means it contains light of all colors (wavelengths).
* Atoms in a star's atmosphere absorb specific wavelengths: Each element has a unique set of energy levels. When light from the star's core passes through its atmosphere, electrons in the atoms can absorb energy at specific wavelengths, causing them to jump to higher energy levels.
* These absorbed wavelengths appear as dark lines in the spectrum: The absorbed wavelengths are missing from the light that reaches us, creating dark lines against the continuous spectrum.
Think of it like this:
Imagine shining white light through a prism. You see all the colors of the rainbow. Now, imagine shining that white light through a cloud of gas. Certain colors will be absorbed by the gas, leaving dark gaps in the rainbow.
These absorption lines are like fingerprints for the elements:
* Each element has a unique set of absorption lines.
* By analyzing the dark lines in a star's spectrum, we can determine the composition of its atmosphere.
In summary, the dark lines in a star's spectrum are caused by the absorption of specific wavelengths of light by atoms in its atmosphere.
