The Size of the Solar System
We are making a scale solar system, where 40 AU  the distance from the Sun to Pluto  is the equivalent of 100 yards. That means the Sun will be on the 0yard line, and Pluto is at the 100yard line.
Thus, if we want to convert AU distances in our solar system to yard distances on our football field, we multiply by 100 yards, then divide by 40 AU.
Example:
Let's say we want to find out how large the orbit of Earth is on our football field. Earth is, by definition, 1 AU from the sun. We plug this into our formula:
Earth's yard line

=

(1 AU)

X

100 yards
40 AU

=

2.5 yards
