Question

What is the shape of the Earth's orbit?

Answer 1

Elliptical Revolution

Explanation:

Earth revolves in an almost circular path around the sun called an elliptical revolution. (It would be a perfectly circular revolution, but nothing is perfect eg rocks hitting earth and the gravity of other planets, so that's why its orbit around the sun is an oval aka ellipsis.)

Answer 2

The Earth's is in an elliptical orbit around the Sun.

Explanation:

Johannes Kepler defined his three laws of planetary motion based on observations of the orbit of Mars. His three laws are:

1. Planets orbits are ellipses with the Sun at one of the foci.
2. The line joining the Sun and the planet sweeps out equal areas during equal time intervals.
3. The square of the orbital period is proportional to the cube of the semi major axis distance.

The Earth's orbit is very nearly circular. The elliptical eccentricity is only 0.0167.

In reality, the elliptical model is too idealistic. The Earth's orbit is constantly changing shape due to the gravitational effects of the other planets.

One quite noticable effect is the time of perihelion. Perihelion is supposed to occur on 3 January at present. In reality it varies from year to year and can occur on 2, 3 or 4 January depending on the positions of the other planets.