Orbital Mechanics 101

A while ago, I made a video about common terms used in orbital mechanics. 

Now, I know...KSP is a game.  Well, yeah, it is but..  It uses a physics engine and for the most part, your creations behave as they should.  Newtonian physics, a basic aerodynamic profile as well as mass, gravity and atmospheric resistance.  All these add up to a pretty realistic simulation.  For all intents and purposes, let's just say KSP is real enough that all the little equations and conversions work in KSP just like in real life.  Somethings are scaled for the sake of playability, but in essese, functional.  

Moving right along, you will no doubt hear terms like apokee or perisapsis, Hohmann transfers, at. al.

Here is just a little guide as to what they mean so when you are watching a video you can understand what they are talking about.

(click to expand)

apokee / apoapsis - farthest point in an orbit from the central body in an elliptical orbit

ascending / descending node - point at which an object passes the north/south (or south/north) planes in an orbit

eccentricity (eccentric orbit) - a measure of how circular (or not) an orbital path is.  0 eccentricity is a circular orbit were 0-1 is a highly elliptical orbit and greater than 1 is a hyperbola

geostationary / Kerbalstationary - orbit at which the satellite orbits at the same phase as the planets rotation (meaning the satellite is always in the same spot in the sky from the ground)

Inclination - the angle of the orbit in relation to the equatorial plane of the central body

perigee / periapsis - closest point in an orbit

polar orbit - orbit with a 90 degree inclination and passes the south and north poles in 1 orbital phase

prograde - pointing in the direction of movement

prograde orbit - orbiting in the same direction as the orbital body

semi-major axis - distance from the apoapsis to the orbital body in an elliptical orbit

semi-minor axis - distance from the closest part of the orbit to the orbital body in an elliptical order

Hohmann transfer - a elliptical orbit used to transfer between two circular orbits in a the same orbital plane

Transfer - changing orbits from 1 orbital body to another e.g. Kerbin > Mun

Hope this helps someone and as always, fly safe-ish