Thermal convection in planetary bodies represents a chaotic dynamical system, which can be mathematically described by a set of nonlinear equations. We have studied classical Boussinesq approximation of thermal convection with no inertial forces. Even for a low Rayleigh number (105) the convection is chaotic and the wavelet analysis of temperature, kinetic energy and surface heat flow time series demonstrates that wavelet spectra are able to yield an insight into the multiscale temporal dynamics of the convecting systems. ¿ 2001 American Geophysical Union