What are the key characteristics of Earth's orbit around the Sun?

Earth's orbit around the Sun is elliptical, nearly circular, and takes approximately 365.25 days to complete.

Earth's orbit around the Sun, also known as its revolution, is not a perfect circle but an ellipse, a shape that is slightly elongated. This elliptical shape means that the Earth's distance from the Sun varies throughout the year. The closest point, called perihelion, occurs around January 3rd when Earth is about 147 million kilometres away from the Sun. The farthest point, known as aphelion, happens around July 4th when Earth is about 152 million kilometres away from the Sun.

The orbit is nearly circular, with an eccentricity of about 0.017. Eccentricity measures the deviation of the orbit from a perfect circle, with 0 being a perfect circle and 1 being a straight line. This low eccentricity means that Earth's orbit is almost circular, but not quite.

The time it takes for the Earth to complete one full orbit around the Sun is called a year. This is approximately 365.25 days. This extra quarter of a day is why we have a leap year every four years, to keep our calendar in sync with the Earth's revolutions.

The Earth's orbit is also inclined at an angle of about 23.5 degrees relative to its orbit. This tilt, combined with the Earth's revolution around the Sun, is what causes the changing seasons. When the tilt is towards the Sun, it's summer for that hemisphere. When it's away, it's winter.

Lastly, the Earth's orbit is affected by the gravitational pull of other planets, primarily Jupiter and Venus. These gravitational forces cause the Earth's orbit to change slightly over thousands of years, a phenomenon known as Milankovitch cycles. These cycles are believed to contribute to the Earth's long-term climate changes, including ice ages.