The sentence you provided is grammatically incorrect and logically flawed. Here's why and how to fix it:

Problems:

* "The moon the most brilliant object in sky" - This is missing a verb and proper structure.

* "more sky" - This phrase doesn't make sense in this context.

Correct and Logical Comparison:

The moon is not the most brilliant object in the sky. The sun is far brighter. Here's a corrected and logical sentence:

* The sun is the most brilliant object in the sky, but the moon is often the most prominent at night.

Explanation:

This sentence clarifies that the sun is the brightest, but the moon's visibility at night makes it appear prominent.