Cosmos. cosmology, cosmo, I'm out of ideas. Core Corona Chromosphere
Solar
the word sun has three letters in it but contains no wordsunshineSundaysundaesunblocksuntansunglassessunburnsunbeamsunflowersundresssunburstsundersundialsundownsunupsunfishsundrysundriessunlesssunkensunlightsunnysunlampsungsunrisesunsetsunroofsunshade
Summer
solar
bolle
The adjective used to describe a noun as of or related to the sun is solar.
Sunflowers
kaleidoscopic
Hawian sun glasses
Sundae, sunbow, sunder, sundew, sundog, sundry, sunken, sunket, sunnah, sunned, sunning, sunset, suntan.
solar system, earth, sun