Milankovitch Cycles, 3 important motions

Milankovitch cycles are the cyclical motions related to the Earth’s orbit. It was discovered by a Serbian Scientist named Milutin Milanković. According to the Milankovitch theory, there is variation in heat coming to the earth from the sun during different kinds of orbital phases. The Milankovitch Cycles also deal with changes in climatic patterns.

Image Source: Hannes Grobe

It has been observed there is a positive relationship between Milankovitch Cycles and Climate Change. As we have discussed in our previous article about Climate Change, it is not just about heating but about cooling too. The Climate has been changing since the formation of the earth. However, this time it has been caused due to industrialization.

The Milankowitch cycles.

Here are the three Milankovitch Cycles.

  • Eccentricity: The measure of the deviation from the earth’s axis from being a near circle to more elliptic and back.
  • Axial Tilt (Obliquity): A measure of tilt in the orientation of perpendicular point in the north pole and earth’s true axis of rotation.
  • Precession: The measure of wobble in Earth’s axial tilt

One: Eccentricity

Eccentricity is the measure of the deviation from being a circle. We know as per Kepler’s law that the orbit of the earth or other planets is not circular but more elliptic. It is caused due to the gravitational force of other planets. A circle has an eccentricity zero, it increases to turn more elliptic. Mathematically it is a deformation.

Depiction of ellipse.

Similarly, the Earth’s axis also changes from being near-circular to more elliptic. This too causes various changes in Earth’s Climate. This was one of the major observations of Milutin Milanković.

In the Milankovitch Cycle of Eccentricity, Earth takes around 100,000 years to complete the cycle for being least eccentric to the more and fro.

Two: Axial Tilt, the obliquity in Milankovitch Cycles

Axial Tilt or Obliquity is a measure of tilt in the orientation of perpendicular point in north pole and earth’s true axis of rotation. Basically, we know that Earth’s axis of rotation is not perfectly upright. It means the earth rotates around its own axis with a tilt. This obliquity varies from 22.1 degrees to 24.5 degrees and fro. As per NASA, currently, the axial tilt of Earth is 23.5 degrees.

Earth 640

The time period taken for this cycle is around 41,000 years. Milankovitch had observed that in between the last 1-3 million years, the Ice Age has been changing in a 41,000 years cycle.

Three: Precession

Precession is the measure of wobble in Earth’s axial tilt. It is also one of the Milankovitch Cycles. In a simpler manner, the pole star will change in the future. This happens because the axis on which the earth is rotating is pointed towards the pole star. The pointing moves in a cycle manner. It is just like moving your pointer finger in a cyclical manner showing some far object. However, in this case, the finger rotates. Isn’t it crazy?

Crazier is the fact that many climate change deniers have argued in the past that climate change is happening due to Milankovitch Cycles only. You can click here to read our article on how the Anthropocentric view has caused damage to the Earth in the name of climate change and sixth mass extinction.

climate change

Why the modern Climate Change is not because of the Milankovitch Cycles?

There have been various Climate Change deniers. However, 97% of the Scientists agree upon the fact that modern climate change is happening because of various factors. One being industrialization. You can click here to read about the impacts of Climate Change in India.

Let’s not accept in the myth of Climate Change denial and a thought that it is just an impact of these cycles.