Here's a breakdown:

* One astronomical unit (AU) is defined as the average distance between the Earth and the Sun.

* This distance is approximately 149.6 million kilometers (93 million miles).

* Using AU allows astronomers to express distances within our solar system in a more manageable way than using kilometers or miles.

For example:

* Mercury: 0.39 AU from the Sun

* Venus: 0.72 AU from the Sun

* Mars: 1.52 AU from the Sun

* Jupiter: 5.20 AU from the Sun

* Saturn: 9.58 AU from the Sun

* Uranus: 19.22 AU from the Sun

* Neptune: 30.07 AU from the Sun

It's important to note that AU is a relative unit of measurement. It's based on the Earth's average distance from the Sun, which means that the distance between the Earth and the Sun can actually vary slightly throughout the year due to Earth's elliptical orbit.