Apoapsis

Definition

Apoapsis is the point in the orbit of an object where it is farthest from the focus, typically a star or planet. In conic sections, it represents one of the key points that describe the shape and size of the orbit.

5 Must Know Facts For Your Next Test

1. Apoapsis occurs in elliptical orbits and is contrasted with periapsis, where the object is closest to the focus.
2. In polar coordinates, apoapsis can be calculated using specific formulas involving eccentricity and semi-major axis.
3. The distance to apoapsis in an elliptical orbit is given by $a(1+e)$, where $a$ is the semi-major axis and $e$ is the eccentricity.
4. Apoapsis can vary depending on whether the central body (focus) is a star, planet, or other massive object.
5. Understanding apoapsis helps in solving problems related to orbital mechanics and satellite trajectories.

Review Questions

• What is apoapsis and how does it relate to periapsis?
• How do you calculate the distance to apoapsis in an elliptical orbit?
• Why is understanding apoapsis important for solving problems involving orbital mechanics?

Related terms

Periapsis: The point in an orbit where the object is closest to the focus.

Eccentricity: A measure of how much an orbit deviates from being circular; denoted as $e$.

Semi-major Axis: The longest diameter of an ellipse, half of which defines its size; denoted as $a$.