Here's why:

* Color and Temperature: A star's color is directly related to its surface temperature.

* Blue Stars: Blue stars emit a lot of energy in the blue and ultraviolet parts of the electromagnetic spectrum, indicating very high temperatures.

* Red Stars: Red stars, on the other hand, emit most of their energy in the red and infrared parts of the spectrum, indicating much cooler temperatures.

Think of it like this: A piece of metal heated in a fire will first glow red, then orange, then yellow, and finally white-hot as it gets hotter. Stars follow a similar pattern, though they are far more complex.