Here's why:

* Constellations are groups of stars that form patterns in the sky. These patterns are purely an illusion created by our perspective on Earth. The stars in a constellation are not actually close to each other in space, they just appear to be close because they are in the same line of sight from our vantage point.

* Constellations do not separate the sky into definite sections. While they are used to divide the sky into areas for mapping and identification, there are no strict boundaries between them.

* Constellations have been given names. These names are often based on the patterns they appear to form, and they have been used for centuries by various cultures around the world.

In summary:

* Constellations are groupings of stars that form patterns.

* They are not defined by definite boundaries.

* They are named to aid in identification.

Instead of saying "separates the sky into definite sections", you could say "are used to divide the sky into areas for mapping and identification" or "form a framework for organizing the night sky".