How accurate is it? It seems that a lot of locations were picked because of them being in museums and other significant places. I guess if it was really accurate they would end up in more inconvenient spots.
Earth's distance from the Sun varies by +/-~2% at its current eccentricity, and the eccentricity isn't constant. So at a distance of ~7.5 km (1:20 mil of Earth's average orbit) you've got a ring about 300 m wide around the Sun to find a museum in.
Other planets further away give you larger rings to search in; you could place Jupiter in a ring ~4 km wide ~39 km away, and it would be within the range of its orbit around the Sun.
That said, while the task is easier than you might think (since there isn't One True Position for each planet), I don't know how well they did.
