To the naked eye, the stars in the night sky all look very similar, the main difference between them being that some are brighter than others. But if you look more carefully, you’ll see that stars come in different colours. Most of them look white, but some are distinctly red in colour, while others are blue. A star’s colour tells us about its temperature and mass, and blue stars are the hottest and most massive of all.
Any star that has three or more times the mass of our Sun will tend to look blue to our eyes. That’s irrespective of other factors such as chemical composition; blue stars, yellow stars and