Emission nebulae appear red because they are associated with cool red giant stars.

Question

Quizplus · Accepted Answer

Emission nebulae appear red because of the presence of ionized hydrogen atoms, which emit red light when they release energy. The color of the associated stars does not necessarily affect the color of the nebulae. Emission nebulae appear red because they are composed of ionized hydrogen gas that emits light at a specific wavelength, known as the H-alpha line, which appears as red. The color of the associated stars does not have a significant effect on the color of the nebula.

Emission Nebulae Appear Red Because They Are Associated with Cool