Earth rotation: an example to teach rigid body motion and environmental monitoring - a fallout of the exploitation of LARES satellite data

The use of satellite laser ranging in combination with other space geodetic techniques allows us to determine Earth's motion with unprecedented accuracy, which is not as simple as usually described in basic textbooks. Besides rotation and revolution there is a wobble of the rotation axis that can be derived by the torque free case in rigid body dynamics. The presence of gravitational perturbations complicates the motion and considering Earth as non-rigid introduces even more variations in the basic Earth motion theory. What is interesting is that also the mass redistribution of air and water on the planet can affect the motion of Earth's rotational axis. Thanks to the millimetre accuracy achievable today, it is possible to correlate very small anomalous rotational axis displacements with global environmental changes such the change in ice melting. The paper will show the experimental motion of the Earth rotation axis and interpret it with the use of the Euler rigid body equations of motion, outlining also the effects of the gravitational perturbations of other bodies in the solar system and of the global climate changes on the Earth rotational axis.