Orbital Inclination If you’d take the orbits of all eight planets, and average them, you’d create what we call the (Laplace’s) invariable plane. Jupiter is roughly like placed on this plane. However, Earth is ‘tilted’ or inclined from the invariable plane. Earth has an inclination of 1.57°; however, not all planets do. Also, the inclination changes over time in cycles of 100 000 years. The inclination can be as much as 3°. Higher Inclination implies a higher obliquity (see Fig. 1.12). Originally, this factor was not part of Milanković’s theory. It is however added to the Milankovitch Cycles, as it impacts the amount of insolation and follows the well-known
Fig. 1.11 – Inclination.
100 000 year pattern.
Fig. 1.12 – Earth’s orbital inclination as seen from the side.
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