The New Horizons spacecraft will travel more than 3 billion miles (5 billion kilometers) on its journey to Pluto, its largest moon, Charon, and the Kuiper Belt beyond. This web site uses the Maine Solar System Model to help us to understand the distances and time involved on this journey.
A nice feature of the Maine Solar System Model is the placement of the Earth model one mile from the Sun. The actual distance from the Sun to Earth is about 93 million miles. That puts the scale of the distances of the Solar System to the distances of the Maine Solar System Model as 93 million to 1.
This distance from the Sun to the Earth is one astronomical unit (AU).
The Pluto-Charon model is placed at Houlton, Maine, 40 miles from the Sun in Presque Isle, because Pluto's orbit averages about 40 AU from the Sun. Pluto will be about 31 AU from Earth when New Horizons arrives because the planet’s orbit is highly elliptical (or oval shaped). This means that the New Horizons spacecraft must travel 31 AU to reach the ninth planet.
The model Sun is in Folsom Hall at The University of Maine at Presque Isle.