Perihelion

Definition

Perihelion is the point in the orbit of a planet, asteroid, or comet at which it is closest to the Sun. It contrasts with aphelion, where the object is farthest from the Sun.

5 Must Know Facts For Your Next Test

1. The perihelion distance can be calculated using calculus-based orbital mechanics equations.
2. At perihelion, an object has its highest orbital speed according to Kepler's laws of planetary motion.
3. The concept of perihelion plays a role in deriving certain integrals related to orbital dynamics.
4. In calculus, understanding elliptical orbits like those involving perihelion may require integration techniques.
5. The date and time of perihelion can shift slightly each year due to gravitational interactions and perturbations.

Review Questions

• Explain how the concept of perihelion relates to Kepler's laws of planetary motion.
• Describe how you would use integration to find distances in elliptical orbits involving perihelion.
• Why does an object's speed increase as it approaches perihelion?

Related terms

Aphelion: The point in the orbit of an object where it is farthest from the Sun.

Elliptical Orbit: An oval-shaped path followed by objects around a central body, described mathematically by ellipses.

Kepler's Laws: Three scientific laws describing the motion of planets around the Sun.