The Sun is a hot star. He lives in outer space and he lives in space, specifically the center of our solar system. The Sun knows all about the solar system and every planet in it from "What Experiment Does Blue Want to Try?" the audio cassette Blue's Treasure Hunt PC and the audio CD Blue's Biggest Hits.
The Sun is yellow. He wears black star-shaped sunglasses. His mouth is red. He has a bright yellow glow.
In "Magenta Gets Glasses", he appears on the living room picture wearing different types of sunglasses. They are:
He also made a cameo appearance on the call reminder on the bulletin board in "The Legend of the Blue Puppy".