The Forbidden Orbits

The asteroid belt looks like a uniform ring of debris. But it isn't — Jupiter's gravity has carved invisible channels through it, forbidding certain orbits from existing. The challenge is making this invisible structure visible, and explaining why it exists.

In 1866, Daniel Kirkwood noticed that asteroids weren't uniformly distributed. At certain orbital distances — where an asteroid would orbit the Sun exactly 3 times for every 1 Jupiter orbit, or 5 times for every 2 — almost no asteroids exist. These orbital resonances make trajectories chaotic over millions of years, gradually ejecting asteroids from those zones.

The gaps are named after Kirkwood, and they're one of the clearest examples of how gravitational resonance shapes the solar system. The same physics creates gaps in Saturn's rings and explains why certain exoplanets have stable orbits while others don't.

We plot 100,000 real asteroids from the Minor Planet Center's orbital database, first in their spatial positions around the Sun, then reorganised into a histogram by orbital distance. The transition between views is the explanatory moment: a dense ring becomes a landscape of peaks and valleys, revealing structure carved by gravity over billions of years.

Each asteroid is rendered as an individual particle using WebGL2. The same data is shown in different arrangements — the transition itself is the explanation.