Final answer:
The hottest stars are blue or blue-white, indicating their high temperature, as they emit most of their energy at shorter wavelengths, while the coolest stars are red, emitting at longer wavelengths.
Step-by-step explanation:
Physicist Max Planck made significant contributions to our understanding of how objects, such as stars, emit light. Using the relationship known as Wien's Law, we know that the color of visible light emitted by a star is an indicator of its temperature. The hottest stars tend to appear blue or blue-white because they emit most of their energy at shorter wavelengths, which are associated with higher temperatures.
Conversely, the coolest stars often appear red because they emit light at longer wavelengths, indicative of lower temperatures. Since the amount of energy emitted at various wavelengths changes with temperature, the color of a star can be used as a sort of cosmic thermometer. While red might be associated with warmth in art and everyday symbols like faucet controls, in the realm of astrophysics, blue represents the hotter temperatures of stars.