A light-year is the distance that light travels in a vacuum in one year. It's a unit of astronomical distance.

500,000,000 centimeters is equal to 5,000 kilometers, which is about the distance across the United States.

This is because a light-year is an incredibly vast distance, and 500,000,000 centimeters is a relatively tiny distance in comparison.

This conversion is mainly used to illustrate the immense scale of space and to provide context for astronomical distances when starting with very small, everyday measurements.