What eccentricity value results in a circular orbit?
The Correct Answer and Explanation is:
The eccentricity value that results in a circular orbit is 0.
Eccentricity is a measure of how much an orbit deviates from being a perfect circle. It is a value between 0 and 1 for elliptical orbits, where:
- Eccentricity = 0 corresponds to a circular orbit.
- 0 < eccentricity < 1 corresponds to an elliptical orbit, with the orbit becoming more elongated as the eccentricity increases.
- Eccentricity = 1 corresponds to a parabolic trajectory, which is not a bound orbit.
- Eccentricity > 1 indicates a hyperbolic trajectory, meaning the object is not bound to the body it’s orbiting and will escape.
In a circular orbit, the distance between the orbiting object and the central body remains constant at all points along the orbit. This is a special case of elliptical orbits, where both foci of the ellipse coincide at the center of the central body, and the eccentricity is zero.
To put it simply, an eccentricity of zero means that the distance between the orbiting body and the center of the orbit doesn’t change—it’s always the same, forming a circle. For planets or satellites orbiting a star or planet, this circular orbit occurs when the gravitational forces acting on the object are perfectly balanced by its velocity, preventing it from moving away or spiraling inward.
An example is Earth’s orbit, which is very close to being circular, but technically, it has a very small eccentricity of about 0.0167, meaning it’s slightly elliptical, though for most purposes, we consider it almost circular.
