Translation:I read a book about the sun, the moon and the stars.
Yes, there are some terrible English translations that are accepted in Duolingo, but this does not make "I read a book about Sun, Moon, and stars" any more correct. The sun in our solar system is always "the sun" and the moon going around Earth is always "the moon." However, one could omit "the" from "stars".
I would not normally capitalize "the Sun" and "the Moon" as they appear here: https://style.mla.org/capitalizing-earth-sun-moon/
I'm in experimental physics and we're trying to measure what's in the core of the sun to see its composition :) sorry dont have Twitter... Or any other social network actually O.o (is Reddit one? :D)
If you want i can give you some other contact and then delete the comment not to spam + privacy :)