By Lacy Barnett

​What is an astronomical unit (AU)?

An astronomical unit (AU) is a unit of distance used to measure space within our solar system.

Definition:
1 Astronomical Unit (1 AU) is the average distance between the Earth and the Sun, which is about 150 million kilometers (93 million miles).

Purpose:
Astronomical units make it easier to describe large distances between objects in space. Instead of saying “579 million kilometers,” we can say “3.87 AU.”

Examples:

• Earth is 1 AU from the Sun.

• Mars is about 1.5 AU from the Sun.

• Jupiter is about 5.2 AU from the Sun.

So, an AU helps astronomers compare distances in the solar system using a simple, standard measurement.

​Venus is 0.72 AU from the sun. What distance is Venus from the sun in Enrique’s scale model?

​Mars is 1.5 AU from the sun. What distance is Mars from the sun in Enrique’s scale model?