Stars display different colors because of their surface temperatures, a relationship astronomers have understood for over a century. The hottest stars burn intensely blue or white, with surface temperatures exceeding 10,000 Kelvin. Medium-temperature stars like our Sun appear yellow or white, radiating around 5,500 Kelvin. The coolest stars glow orange or deep red, with temperatures below 3,500 Kelvin.
This color-temperature connection stems from basic physics. All hot objects emit electromagnetic radiation across a spectrum of wavelengths. Hotter objects radiate more energy at shorter wavelengths, which our eyes perceive as blue light. Cooler objects shift their peak radiation toward longer wavelengths, appearing orange or red.
Astronomers classify stars using spectral types based on these colors and temperatures. The mnemonic "Oh Be A Fine Girl Kiss Me" helps recall the sequence from hottest to coolest: O, B, A, F, G, K, M. Our Sun belongs to the G-class, which places it in the middle range of stellar temperatures.
A star's color also reveals its composition and age. Young, massive stars burn hotter and appear blue. Older stars gradually cool and redden over billions of years. Red dwarfs, the coolest and most common stars, burn slowly and can live for trillions of years, far longer than the current age of the universe.
When observing the night sky, factors beyond temperature affect apparent color. Earth's atmosphere scatters light and can distort colors, particularly for stars near the horizon. Dust between stars and Earth also reddens starlight. Additionally, human eyes perceive colors differently under low light conditions, making some colors harder to detect.
Understanding stellar colors provides astronomers with a rapid way to estimate a star's fundamental properties without detailed spectroscopic analysis. This simple