Here's why:

* Color and Wavelength: The color of light is determined by its wavelength. Red light has the longest wavelength visible to the human eye, while blue light has the shortest.

* Star Temperature: The temperature of a star is directly related to the wavelengths of light it emits. Hotter stars emit more blue light, while cooler stars emit more red light.

* Red Stars: Red stars are relatively cool compared to other stars. Their surface temperatures are typically around 3,500 Kelvin or less.

So, because red stars are cooler, they emit more light in the longer, red wavelengths of the electromagnetic spectrum.