The Plane of the Kuiper Belt

We present a robust method for measuring the effective plane of the Kuiper belt. The derived plane has an inclination with respect to the ecliptic of 1 86 and an ascending node of 81 6, with a 1 σ error in pole position of the plane of 0 37. The plane of the Kuiper belt is inconsistent with the invariable plane, the plane of Jupiter, and the plane of Neptune at the greater than 3 σ level. Using linear secular perturbation theory, we show that the plane of the Kuiper belt is expected to oscillate about the position of the invariable plane with a period of 1.9 million years and an amplitude of 1 2. The present predicted position of the plane of the Kuiper belt has an inclination with respect to the ecliptic of 1 74 and an ascending node of 86 7, within 0 20 of our measured position.