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How to Describe an Orbit
There are six Classical Orbital Elements (see next section) that are necessary to tell us all
we need to know about an orbit and a satellite's place in it. These elements help us
describe:
- Orbit Size
- Orbit Shape
- Orbit Orientation
- Orbit Location
Elliptical Geometry
- An ellipse looks like an oval, or squashed circle.
- The longest line drawn from one end of the ellipse (through the center) to the other
side is called the major axis.
- Every ellipse has two foci (F and F'), and the distances between each focus
and the center of the ellipse are equal (c). For a circle, the two foci lie on top of each other.
- The point on the semi-major axis closest to the Earth is called perigee,
while
the point on this axis farthest from the Earth is called apogee.
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