In spectral classification, stars are ordered from hottest to coolest, blue to red.

In spectral classification, stars are ordered from hottest to coolest, blue to red.

• A. True
• B. False
• C. It depends on the star
• D. Only for giants

Answer: (A)

Stars are classified by surface temperature, and that temperature determines their color. The spectral sequence runs from hottest to coolest, starting with O-type stars that appear blue and ending with the coolest M-type stars that appear red. This ordering—hottest to coolest, blue to red—matches how a star’s peak emission shifts with temperature: hotter stars peak at shorter wavelengths (blue/white light), while cooler stars peak at longer wavelengths (redder light). This relationship holds across luminosity classes, so giants and dwarfs share the same temperature-based sequence; the color and spectral type depend on temperature, not on size or brightness.

Stars are classified by surface temperature, and that temperature determines their color. The spectral sequence runs from hottest to coolest, starting with O-type stars that appear blue and ending with the coolest M-type stars that appear red. This ordering—hottest to coolest, blue to red—matches how a star’s peak emission shifts with temperature: hotter stars peak at shorter wavelengths (blue/white light), while cooler stars peak at longer wavelengths (redder light). This relationship holds across luminosity classes, so giants and dwarfs share the same temperature-based sequence; the color and spectral type depend on temperature, not on size or brightness.