Why is a star considered a good $\mathrm{blackbody}$ radiator?

• A. Because it absorbs and emits all wavelengths of electromagnetic radiation efficiently, closely following the $\mathrm{blackbody}$ radiation curve.
• B. Because it only emits visible light and reflects most other wavelengths.
• C. Because it is completely transparent to all forms of radiation.
• D. Because it emits radiation only at a single wavelength determined by its $\mathrm{mass}$.

Answer: (A)

Verified step by step guidance

1. Understand the concept of a blackbody: A blackbody is an idealized physical object that absorbs all incident electromagnetic radiation, regardless of wavelength or angle, and emits radiation with a characteristic spectrum that depends only on its temperature.
2. Recognize that stars, including our Sun, have dense, hot plasma surfaces that absorb nearly all incoming radiation, making them excellent absorbers across a wide range of wavelengths.
3. Note that stars emit radiation across a continuous spectrum that closely matches the theoretical blackbody radiation curve, which depends on their surface temperature, not on their mass or any single wavelength.
4. Understand that the emission is not limited to visible light but spans a broad range of electromagnetic wavelengths, including infrared and ultraviolet, consistent with blackbody radiation behavior.
5. Conclude that because stars both absorb and emit radiation efficiently across all wavelengths and their emission spectrum follows the blackbody radiation curve, they are considered good blackbody radiators.