Venus: Moment of Inertia and Length of Day

Earth-based radar observations in 2006–2019 enable the first measurement of the spin precession rate and moment of inertia of Venus. The observations also show that the spin period of the solid planet changes by tens of minutes. The length-of-day variations are due to variations in atmospheric angular momentum transferred to the solid planet.



University of California, Los Angeles


Jean-Luc Margot