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Issue 4.5

FEATURE

REALScience

Basic Planetary Motion

Issue: 4.5 (May/June 2006)
Author: JC Cruz
Author Bio: JC is a freelance engineering consultant currently residing in British Columbia. He develops custom OS X applications and teaches origami at the local district libraries.
Article Description: No description available.
Article Length (in bytes): 37,914
Starting Page Number: 21
Article Number: 4509
Resource File(s):

Download Icon 4509.zip Updated: 2013-03-11 19:07:59

Related Web Link(s):

http://nssdc.gsfc.nasa.gov/planetary/factsheet
http://en.wikipedia.org/wiki/Planetary_orbit
http://en.wikipedia.org/wiki/Two-body_problem
http://en.wikipedia.org/wiki/N-body_problem
http://en.wikipedia.org/wiki/Gravitational_constant
http://www.nineplanets.org
http://en.wikipedia.org/wiki/Ellipse

Excerpt of article text...

In my previous article, I covered the basic physics behind harmonic motion. I also introduced a new ODE algorithm, known as the Runge-Kutta Fourth Order (RK4), to replace the simple Euler's Method. I have shown the basic mathematics behind this new algorithm as well as some pertinent issues. I have also demonstrated how to use RK4 to simulate a prime example of harmonic motion, the simple pendulum.

Today, I will be discussing the basic physics behind planetary motion. I will cover some of the issues involved when simulating a planetary system. Later on, I will demonstrate how to use a vectorial version of RK4 to simulate a three-body system.

So pay attention, bright readers. This is going to be an interesting ride.

Basic Concepts

Astronomical Units of Measure

One notable aspect about planetary motion is that all data being processed are large in orders of magnitude. Masses are often in the order of at least a billion kilograms. The same is also true for other quantities such as velocities and positions.

...End of Excerpt. Please purchase the magazine to read the full article.