As thermonuclear fusion proceeds in its core, the Sun loses mass at a rate of 3.64 X 109 kg/s. During the 5 000-yr period of recorded history, by how much has the length of the year changed due to the loss of mass from the Sun? Suggestions: Assume the Earth’s orbit is circular. No external torque acts on the Earth–Sun system, so its angular momentum is conserved. If x is small compared to 1, then (1 + x) n is nearly equal to 1 + nx.