What is an astronomical unit (AU)? The average distance between Earth and the Sun. The current distance between any planet and the Sun. Any very large unit,such as a light-year. The average distance between any planet and the Sun. The current distance between Earth and the Sun.

The correct answer is: **The average distance between Earth and the Sun.**<br /><br />An astronomical unit (AU) is a unit of length, approximately the average distance from Earth to the Sun. It's a useful unit for measuring distances within our solar system. While the Earth-Sun distance varies slightly throughout the year due to Earth's elliptical orbit, the AU represents the average distance.<br />