The Milankovitch Cycle
Earth revolves around the sun in a roughly circular orbit. But roughly every 200,000 years, its orbit becomes more eccentric from gravitational interactions.
It’s close to circular now. But like a pendulum, eccentricity will swing back the other way.
It’s because Venus is so close and Jupiter is so large that gravity affects its orbit.
In the eyes of Milankovitch, there’s been a noticeable trend in climate, temperature and seasons due to this cycle.