Chandler Wobble
A small periodic nutation wobble of Earth's rotational axis relative to its solid crust with a period of ~433 days.
Governing formula
Period T ≈ 433 days, Amplitude ~ 3–15 meters
SI unit
Arcseconds or Meters at Surface
In depth
Discovered by Seth Carlo Chandler in 1891. Arises from Earth not being a perfectly rigid sphere. Excitation is maintained by fluctuating ocean bottom pressures and atmospheric surface pressure variations.
Examples in the real world
Astronomical observatories making polar motion corrections to keep precise Earth orientation frames.