Respuesta :
They are less brighter because of the lesser amount of heat in them. In fact, sunspots are identified as areas that don't subject to heat very much, and are shown as dark spots because it's not hot enough to glow the yellowish orange color we usually see
Hope this helped!
Thanks!
~Steve
The spots on the sun are cooler areas than the hot yellow areas because sunspots have less heat in them than the rest of the sun does.