Here's why:

* The Sun's Atmosphere: The Sun's outer layer, called the photosphere, emits a continuous spectrum of light, containing all wavelengths (colors).

* Elements in the Photosphere: This photosphere contains various elements like hydrogen, helium, sodium, and more.

* Absorption: When light from the hotter interior of the Sun passes through the photosphere, electrons in these elements absorb specific wavelengths of light. This absorption happens when an electron jumps to a higher energy level.

* Dark Lines: These absorbed wavelengths are missing from the continuous spectrum, creating dark lines that we call Fraunhofer lines.

In summary: Fraunhofer lines are dark lines in the solar spectrum, caused by the absorption of specific wavelengths of light by elements in the Sun's photosphere.