How is the blue giant star the hottest star if the color is blue you thought blue is a cold color?

Answer 1

It all has to do with wavelengths of energy. The wavelengths that we absorb and sense as heat tend to be the longer wavelengths just below the visable spectrum, i.e infrared. The visible wavelengths of energy that we see as light cover a range we perceive as the spectrum. The longest wavelengths the eye can detect are red, the shortest blue to violet. The hotter something is the faster its molecules vibrate and the shorter the wavelengths of energy it gives off. Once the frequency enters the visible range the item appears to glow. It would start with red-hot. As it gets hotter it might give off energy across the visible spectrum and become white hot. If it gets really hot it starts going beyond the visible spectrum and the only thing you could see would be the blue wavelengths. You can't see the higher wavelenthgs just like you can't hear the high pitch of a dog whistle. We tend to associate warm with things in the red to yellow end of the spectrum, like fire or a redhot Poker because that is what we are used. Things that are blue tend to be just giving off blue light -- short, high-energy wavelengths but in small quantity. So we think of things that are blue as being cold. We never experience true blue heat because if you were standing next to something glowing blue-hot you would be burnt to a crisp. So the blue stars' are giving off a lot more enregy and in higher wavelengths than our cooler yellow sun, but luckily they are far enough away that they are just a cool-blue dot in the night sky.

Answer 2

The color of a star does not represent its temperature in the same way as it does for common objects like fire. Blue giant stars appear blue due to their extremely high temperatures, which can reach tens of thousands of degrees Celsius. Blue light has a higher energy level than red light, hence the perception of blue being "hot".