How does the emission spectrum tell how hot a star is?

The emission spectrum of a star reveals the wavelengths of light emitted by its gases, which are influenced by temperature. Hotter stars emit light at shorter wavelengths, often appearing blue or white, while cooler stars emit light at longer wavelengths, appearing red or orange. By analyzing the spectral lines, astronomers can determine the star's temperature, as the intensity and distribution of these lines shift according to thermal radiation laws, specifically Wien's Law. Thus, the emission spectrum serves as a fingerprint for understanding a star's thermal properties.