This tells of the envy of the Moon wanting to have a chance to be the Sun for one day. The sun is harsh though and will only agree to swap if the Moon agrees to make the swap permanent. The Moon has one night to make the decision. Paying extra attention to everything that takes place in the night, the Moon of course realizes that nighttime has many charms, and in the end decides not to swap.
Normally I cut children's books some slack, and let them get away with more than I would a book written for older children or adult audiences, but this one didn't impress me at all. The first problem is that the Moon was a 'he' when the Moon has typically and traditionally been associated with femininity and goddesses. The sun's gender wasn't made clear, so conceivably it could have been female, but I couldn't help but wonder why the Moon was masculinized here.
On top of that, the story suggests how stupid the Moon is - having failed to notice all that beauty which 'he' notices on that one night; the observations lead to the Moon resolving to stay. What bothered me about this was that it suggests that a person should be content to 'stay in one's station in life' and never strive or hope for more. I don't think this is good advice to pass on to children.
Admittedly, this would have been worse had the Moon been given a female gender which would then suggest that the masculine sun was dictating what the feminine Moon should do: stay below that glass ceiling as it were, because it couldn't handle a tough day job. I don't have any idea if the author saw it that way, but it still doesn't change the point about ambition. Too much ambition, or ruthless or blind ambition is a bad thing, but healthy ambition - a desire to improve one's station and an aim be the best one can be at something is a good thing, and this book seemed intent upon slapping that down.
I think this same story could have been much better written: for example as a joint decision by the two to swap for a day/night, and then by mutual agreement decide to return to their original stations, having learned they are both happier where they were. I just did not like the way it was handled here. For this reason, I cannot commend this one as a worthy read.