Comet Orbits!
The orbit depends on the value of the total energy E. If E is negative, the body is bound to the Sun and the orbit is an ellipse. If E is positive, the body is not bound to the Sun, starting with zero velocity at infinity, and the orbit is a parabola. Consider the following equation:
R = q (1+e) /(1+ e cos@)
R = distance from the focus containing the sun
q = perihelion distance
@ = angle measured from perihelion
e = eccentricity
By specifying the eccentricity (e), we can determine a particular conic shape and the total energy (E) See table below:
| SHAPES | ENERGY | ECCENTRICITY |
| Ellipse | E< 0 | e< 1 |
| Parabola | E = 0 | e = 1 |
| Hyperbola | E>0 | e > 1 |
For an elliptical orbit, the PERIHELION distance q is given by:
q = A (1-e)
The APHELION distance q is given by:
q = A (1+e)
Notes:
Perigee: When a satellite traces out an orbit about the center of the earth, its closest point is called the perigee. The apogee is the opposite.
Perihelion and Aphelion: They refer to the orbits around the sun
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Orbits are paths or trajectories of an object through space. A force of attraction or repulsion from a second object (i.e. a planet) will usually cause the path to curve. Usually, one object will revolve around another such as the planetary orbits of the Earth around the Sun or an electron around an atom's nucleus.
