Here's why:

* Astronomical Unit (AU): This is the average distance between the Earth and the Sun. It's about 93 million miles (150 million kilometers).

* Light-Year: This is the distance light travels in one year. Light travels at an incredible speed (approximately 186,282 miles per second or 299,792 kilometers per second).

In comparison:

* One light-year is equal to about 63,241 astronomical units.

Think of it this way: You could fit about 63,000 of the Earth-Sun distances into one light-year!