About the project

A city-scale model of the solar system you can walk.

Most solar-system models cheat. They shrink the planets but keep them close together, because honest distances are enormous. SolarSystem.city does the opposite: it keeps the scale honest and lets the city carry the distance. Pick a real object in your city to stand in for the sun, and every planet's size and orbit follow from real astronomy — never invented.

The sun object

Every adventure is anchored to a single real-world landmark that plays the role of the sun — in New York, it's The Sphere (the Koenig Sphere) in Liberty Park. Its real diameter sets the scale for the entire system. Once the sun's size is fixed, the size of every planet and the distance to every orbit are fully determined.

How the scale works

The math is a single ratio. If the sun is rendered at a few metres across instead of its true 1.39 million kilometres, that ratio is the scale factor:

scale_factor = real_sun_diameter / sun_object_diameter

Every other number divides by that same factor. A planet's rendered size is its real diameter divided by the scale factor; its distance from the sun object is its real orbital distance divided by the scale factor. Nothing is fudged to fit — if Neptune ends up kilometres away, then that's how far you walk.

One deck, every city

The cards carry no city information at all. A card is two things: a QR entry point and a printed border that the AR view uses as an image target to lock real-world scale. Which city you're in is resolved at runtime from your location, so the same physical deck produces a different true-scale walk in every supported city.

No accounts, no tracking

There are no logins and no personal data. Your progress through an adventure lives only in your browser's local storage. Clear it and you start fresh.