Orbital Behaviour – A Level Environmental Science AQA Revision

Earth revolves around the Sun in an elliptical (oval-shaped) orbit with the Sun at one focus point.
The time it takes to complete one full orbit is approximately 365.25 days, which is the length of a year.
The tilt of Earth’s axis and its orbital eccentricity are two major factors affecting the planet’s climate and thus the conditions for life.

Earth’s axis is tilted at an angle of about 23.5 degrees relative to its orbital plane.
This tilt is responsible for the changing seasons as the Earth orbits the Sun, with different parts of the Earth receiving varying amounts of sunlight throughout the year.
During the summer solstice, the tilt of Earth’s axis is oriented towards the Sun, resulting in longer daylight hours and higher solar radiation, while during the winter solstice, the tilt is away from the Sun, leading to shorter daylight hours and reduced solar radiation.

The eccentricity of Earth’s orbit describes its departure from a perfect circle. Its value varies over time due to gravitational interactions with other planets, with values ranging from nearly 0 to about 0.06.
When the eccentricity is higher (the orbit is more elliptical), there are larger seasonal temperature variations and thus more extreme weather conditions.
These variations in Earth’s orbit are described by Milankovitch cycles, which have had profound impacts on Earth’s long-term climate and have been linked to the timing of ice ages.

Stable orbital behaviour enables Earth to maintain a relatively stable climate suitable for life.
Earth’s orbital parameters ensure it remains within the Sun’s habitable zone, where conditions are right for liquid water to exist, which is a key requirement for life.
Significant changes in orbital behaviour could lead to drastic climate change, threatening biodiversity and disrupting ecosystems.

Understanding Earth’s orbital behaviour is also important for climate modelling and prediction.
By tracing back the variations of Earth’s orbit, scientists can understand past climate changes and predict future climate trends.
Specifically, knowledge of Milankovitch cycles can help predict long-term changes in Earth’s climate, contributing to our understanding of climate change.