It should come as no surprise that the amount of sunlight reaching our planet influences our climate. Serbian mathematician and astronomer Milutin Milankovitch theorized that fluctuations in Earth’s climate are caused by changes in the amount of sunlight the planet receives, and that these changes follow specific cycles. Milankovitch calculated these cycles over the last 600,000 years and suggested they are responsible for ice ages and subsequent warmer interglacial periods. Geologists examining sediment layers in areas that were once ancient ocean beds confirmed the existence of Milankovitch cycles.
The amount of sunlight reaching Earth depends on three parameters that change over long time scales: the tilt of Earth’s axis, the eccentricity of its orbit, and the precession (wobble) of its axis. Because of the tilt of Earth’s axis, we experience seasons. Earth’s orbit is nearly circular but slightly elliptical, so its distance from the Sun varies. The precession of Earth’s axis is a slight wobble over time, similar to the wobbling of a spinning top.
Earth’s orbit is more circular than those of any other planet in our solar system. Because of this, the length of our seasons is approximately equal, but over long periods, these can change. The tilt of our planet’s axis is 23.4°, but it has varied in past ages from 22.1° to 24.5°. The precession of Earth’s axis also shifts over extended timescales. All three factors influence Earth’s climate because they alter the amount of sunlight reaching its surface.
The climate changes driven by these three factors are known as Milankovitch Cycles. The mathematician/astronomer calculated these cycles, and geologists have confirmed his calculations through examination of sediment layers from ancient ocean beds. The last Ice Age occurred about 20,000 years ago, when woolly mammoths roamed on ice sheets covering much of North America, Europe, and Asia. Over the past 10,000 years, the climate has remained remarkably stable, enabling the development of advanced civilizations.
As scientists study exoplanets beyond our solar system, they seek to determine their Milankovitch cycles because these cycles are another critical factor in assessing whether a planet can support advanced life. Mars has Milankovitch cycles that are far more extreme than Earth’s, which limits its potential to sustain life. Without the stabilizing influence of our relatively large Moon, Earth’s axis could oscillate up to 30°, leading to severe climate fluctuations. The more we learn about our unique planet, the more evident it becomes that God has finely tuned it to meet all our needs.
— Roland Earnst © 2026
Reference: space.com