What causes the colours of stars?

The colours of stars depend on their surface temperature, with hotter stars appearing blue and cooler stars appearing red. Blue stars, like Rigel, are the hottest, with temperatures exceeding 30,000 K. Red stars, like Betelgeuse, are cooler, with temperatures below 3,500 K. Yellow stars, like the Sun, fall in between. These colours are determined by the star’s blackbody radiation and help astronomers understand a star’s age, size, and composition.