https://dictionary.cambridge.org/dictionary/english/everything-under-the-sun https://dictionary.cambridge.org/dictionary/english/everythi... https://forum.word

https://dictionary.cambridge.org/dictionary/english/everything-under-the-sun https://dictionary.cambridge.org/dictionary/english/everythi... https://forum.wordreference.com/threads/playing-in-under-the-sun.1443759/ https://forum.wordreference.com/threads/playing-in-under-the... https://www.quora.com/Given-that-Sun-is-a-name-of-a-star-and-all-proper-nouns-should-be-capitalized-why-is-Sun-written-as-sun https://www.quora.com/Given-that-Sun-is-a-name-of-a-star-and... Just did some random googling, and a lot of people seem to disagree with you.