Here's why:

* Blackbody Radiation: The sun acts like a blackbody radiator, meaning it emits light across a continuous range of wavelengths due to the thermal motion of its atoms.

* Fraunhofer Lines: However, the sun's spectrum is not perfectly continuous. There are thousands of dark lines called Fraunhofer lines that appear at specific wavelengths. These lines are caused by the absorption of certain wavelengths by elements in the sun's atmosphere.

In summary:

* The sun's spectrum is dominated by a continuous range of wavelengths due to blackbody radiation.

* The presence of Fraunhofer lines indicates that the spectrum is not perfectly continuous, but rather has subtle interruptions.

Therefore, while technically not perfectly continuous, the sun's spectrum is often considered continuous for most practical purposes.