Terms
Period
-
The period of an orbit, usually denoted T, is the total time taken for an
object to complete one full revolution on its orbit.
Kepler's First Law
-
The planets orbit the sun in ellipses, with the sun at one focus.
Kepler's Second Law
-
The radius of a planet sweeps out a constant area per unit time.
Kepler's Third Law
-
where
T is the period,
G is the gravitational constant, and
M is the mass
of the sun.
Eccentricity
-
The eccentricity is a measure of the elongation of an ellipse. It is defined
as:
where
a and
b are the semimajor and semiminor axis lengths respectively.
Aphelion
-
The point of a planet's furthest distance from the sun on its orbit.
Perihelion
-
Is the point of a planet's closest approach to the sun.
Apogee
-
For an earth orbit, the furthest distance from the earth.
Perigee
-
For an earth orbit, the closest distance to the earth.
