How special is the solar system? The history of astronomy has mostly been a one-way journey from a worldview in which our solar system is orderly (and divine) to a view in which we are not special. Our solar system’s planets, once thought to dance in god-ordained perfect circles in a “music of the spheres,” deviate from circular orbits. Johannes Kepler, who demonstrated the non-circular orbits of the planets, tried to restore a sense of heavenliness by latching onto a new pattern for their orbits based on Plato’s mathematical solids—but that notion was discredited many years later with the discovery of Uranus.

So when, on a sunny afternoon in California last year, I discovered a set of patterns that seem to rule planetary systems other than our own, I was skeptical. Were these patterns real, or were they an illusion? And if real, what did they mean about our solar system’s place in the cosmos?

In addition to our solar system, we now know of over 400 multi-planet systems, thanks largely to the Kepler Mission. Kepler is a NASA spacecraft (named after the 17th century German astronomer) that was launched in 2009 for the sole purpose of discovering exoplanets—worlds orbiting other stars. It finds those exoplanets by continuously measuring the brightnesses of about 100,000 stars and waiting for the starlight from any of them dim ever so slightly due to the shadow of a planet in transit. The transit of each planet is unique, allowing the discovery of multiple planets orbiting the same star.