Ellipses are oval shapes.
In more technical terms, an ellipse is a plane curve that results from the intersection of a cone by a plane in a way that produces a closed curve.
All planets orbit the Sun in ellipses, not perfect circles.
This is because their trajectories are affected by the gravitational forces of not just the Sun, but each other as well.
Some ellipses are nearly flat, while others are almost circular.
A planet’s aphelion is the point in its elliptical orbit when it is farthest from the Sun; its perihelion is its closest point to the Sun.
A planet moves faster at its perihelion than at its aphelion.
When we mention the distance or speed of a planet’s orbit, we are referring to the average, unless otherwise specified.
Aphelion and perihelion are, respectively, a planetary orbit’s farthest and nearest points to the Sun.
All planets’ orbits are elliptical, like flattened circles, and the Sun is not in the exact center of any orbit.
When we say the Sun is the center of the solar system, we are not speaking in terms of precise location.