Colour and temperature of the stars 🥵 A star's color provides a direct measurement of its surface temperature; the hottest stars shine blue, while the coolest are dull orange or red. The sun has a surface temperature of 5,500 K, typical for a yellow star. Red stars are cooler than the sun, with surface temperatures of 3,500 K for a bright red star and 2,500 K for a dark red star. The hottest stars are blue, with their surface temperatures falling anywhere between 10,000 K and 50,000 K. Video –