In physics and astronomy, an orbit is the gravitationally curved trajectory of an object, such as the trajectory of a planet around a star or a natural satellite around a planet. 


Normally, orbit refers to a regularly repeating trajectory, although it may also refer to a non-repeating trajectory. 

To a close approximation, planets and satellites follow elliptic orbits, with the center of mass being orbited at a focal point of the ellipse, as described by Kepler's laws of planetary motion.

For most situations, orbital motion is adequately approximated by Newtonian aka classical mechanics , which explains gravity as a force obeying an inverse-square law.

But there are exceptions

However, Albert Einstein's general theory of relativity, which accounts for gravity as due to curvature of spacetime, with orbits following geodesics, provides a more accurate calculation and understanding of the exact mechanics of orbital motion. This is especially important when dealing with very massive and dense astronomical objects and how it affects objects orbiting them. 

Typical orbits are:

  • Circular orbit ( pretty rare)
  • Elliptical orbit
  • Parabolic orbits
  • Hyperbolic orbits

The grey is a circular orbit, the red circle is an elliptical orbit. The green is a parabolic orbit(or path) and the blue is a hyperbolic path

Adapted from: Wikipedia contributors. (2020, August 25). Orbit. In Wikipedia, The Free Encyclopedia. Retrieved 03:44, September 1, 2020, from https://en.wikipedia.org/w/index.php?title=Orbit&oldid=974841771