Scientists don't actually use AUs (Astronomical Units) to measure distances within the solar system. They use AUs to measure distances between stars and other celestial objects outside the solar system.

Here's why:

* AU is defined as the average distance between the Earth and the Sun. This makes it a convenient unit for measuring distances within our solar system.

* Distances within the solar system are relatively small. Using kilometers or miles would result in very large and unwieldy numbers.

* AUs are easy to visualize. We can relate distances within the solar system to the familiar distance between Earth and the Sun.

For example:

* Mars is about 1.5 AUs from the Sun.

* Jupiter is about 5.2 AUs from the Sun.

However, when dealing with distances between stars and galaxies, AUs become too small. For these larger distances, scientists use other units:

* Light-years: The distance light travels in one year.

* Parsecs: A unit based on parallax, a technique used to measure distances to stars.

So, while AUs are a practical and intuitive unit for measuring distances within the solar system, they are not used for measuring distances between stars and other celestial objects outside our solar system.