As the sign says, this model of the planet Neptune is part of the world's longest Virtual Solar System Drive. The Drive has models of the planets reduced to a scale of 1:38 million, with the distance to placements along the road scaled similarly - "The Sun" is at the Siding Spring Astronomical Observatory. If you'd care to see more detail (or even take the drive, which extends 200km in different directions), the information is here. www.2tinytravellers.com/post/solarsystemdrive .
Along the way you'll even see fences, so Happy Fence Friday everyone.