# Semi-Major Axis

The Semi-Major Axis of an object's elliptical orbit is the distance from the center of the ellipse to the most distant point in the orbit. In other words, the Semi-Major Axis is half the distance between the pericenter and apocenter of the orbit. Semi-Major Axis is a way to represent the size of an orbit; objects with a smaller Semi-Major Axis will orbit closer to their Orbital Parent than objects with a larger Semi-Major Axis.

The Semi-Major Axis of an object with a hyperbolic trajectory is negative.

Semi-Major Axis is one of the six orbital elements that described an object's orbit.

## Contents

## Property DetailsEdit

### LocationEdit

The Semi-Major Axis property is located in the Orbital Elements section of the Motion tab of an object's properties panel, if that object has an Orbital Parent.

### UnitsEdit

Semi-Major Axis can be viewed and edited using the following units:

- Milky Way Galaxy radius (milky way) = 5.5×10
^{4}light year - Parsec (parsec) = 3.08568025×10
^{16}m - Light-year (light year) = 9.46073047×10
^{15}m - Astronomical Unit (AU) = 1.495978707×10
^{11}m - Solar radius (sun) = 6.955×10
^{8}m - Lunar distance (lunar dist) = 3.844×10
^{8}m - Light-second (light sec) = 2.99792458×10
^{8}m - Jupiter radius (jupiter) = 6.9911×10
^{7}m - Earth radius (earth) = 6.37101×10
^{6}m - Moon radius (moon) = 1.7371×10
^{6}m - Kilometer (km) = 1000 m
- Meter (m) is the SI base unit for length
- Centimeter (cm) = 0.01 m
- Millimeter (mm) = 0.001 m