# List of orbits

Various Earth orbits to scale; innermost, the red dotted line represents the orbit of the International Space Station (ISS); cyan represents low Earth orbit, yellow represents medium Earth orbit, and the black dashed line represents geosynchronous orbit. The green dash-dot line represents the orbit of Global Positioning System (GPS) satellites.

The following is a list of types of orbits:

## Eccentricity classifications

There are two types of orbits: closed (periodic) orbits, and open (escape) orbits. Circular and elliptical orbits are closed. Parabolic and hyperbolic orbits are open. Radial orbits can be either open or closed.

## Synchronicity classifications

• Synchronous orbit: An orbit whose period is a rational multiple of the average rotational period of the body being orbited and in the same direction of rotation as that body. This means the track of the satellite, as seen from the central body, will repeat exactly after a fixed number of orbits. In practice, only 1:1 ratio (geosynchronous) and 1:2 ratios (semi-synchronous) are common.
Geostationary orbit as seen from the north celestial pole. To an observer on the rotating Earth, the red and yellow satellites appear stationary in the sky above Singapore and Africa respectively.

## Orbits in galaxies or galaxy models

• Box orbit: An orbit in a triaxial elliptical galaxy that fills in a roughly box-shaped region.
• Pyramid orbit: An orbit near a massive black hole at the center of a triaxial galaxy. The orbit can be described as a Keplerian ellipse that precesses about the black hole in two orthogonal directions, due to torques from the triaxial galaxy.[7] The eccentricity of the ellipse reaches unity at the four corners of the pyramid, allowing the star on the orbit to come very close to the black hole.
• Tube orbit: An orbit near a massive black hole at the center of an axisymmetric galaxy. Similar to a pyramid orbit, except that one component of the orbital angular momentum is conserved; as a result, the eccentricity never reaches unity.[7]

## Pseudo-orbit classifications

A diagram showing the five Lagrangian points in a two-body system with one body far more massive than the other (e.g. the Sun and the Earth). In such a system, L3L5 are situated slightly outside of the secondary's orbit despite their appearance in this small scale diagram.