Does the Earth’s axis tilt change?

Scientists have discovered that in a time period of 40 000 years, the Earth’s axial tilt varies between 22.1 degrees and 24.5 degrees, due to climate change.

The axis is an unseeable line around which an object spins or rotates. These objects can range from a tiny particle, smaller than a single atom, to a star with the mass of a thousand suns. In both cases, an object’s axis runs through the centre of mass, also known as barycentre.

The centre of mass is a point where an outside force acting on the object acts as if the object were situated at just that point, where the object appears balanced. It is important to note that the Earth’s centre of mass varies, due to ocean tides shifting. However, it is enough to radically shift the planet’s axis.

© NASA/JPL-Caltech

The Earth’s axis is not perpendicular, as it has an axial tilt. The tilt is the angle between the planet’s orbital axis and rotational axis. The orbital axis is perpendicular to the ecliptic or orbital plane, which is the thin disk surrounding the Sun and extending to the edge of the solar system.

It is important to note that Earth’s axial tilt is approximately 23.5 degrees. Due to this tilt, the Sun shines on different latitudes at different angles throughout the year. Because of this, seasons occur every year. However, Earth’s axial tilt changes.

During a cycle that averages about 40 000 years, the tilt varies between 22.1 degrees and 24.5 degrees. Due to the tilt changes, the seasons as we know them can become more exaggerated. An increase in tilt means more severe seasons, which translates to warmer summers and colder winters, while a decrease in tilt means less severe seasons. Summers will thus be cooler and winters warmer.

There are many theories as to why the Earth’s axial tilt is changing. However, scientists believe that the tilt change is caused by climate change. It is believed that due to the ice glaciers melting, the earth contains more water, which leads to a change in the Earth’s axis. This change can have an effect on the Earth’s axial tilt.