S (the synodic period) = 360 / (360/ P - 360/365.256) days. S (the synodic period) = 360 / (360/365.256 - 360/ P) days. A diagram showing the relationship between orbital size and synodic periods. As the planets move around the Sun they change their positions relative to each other.
Some geologists consider that mantle plumes are generated in the lower levels of the asthenosphere by the decay of concentrations of radioactive isotopes. However, many believe that they are generated at much deeper levels in the lower mantle, perhaps even at the boundary of the mantle with the outer core.
Convection Currents in Earth. In Earthâs mantle, large amounts of heat are transferred by convection currents, as shown in Figure 10. Heat from the core and the mantle itself causes convection currents in the mantle. Mantle Convection. d. Figure 10Mantle Convection Most geologists think that convection currents rise and sink through the mantle.