The Astrophysics Spectator

January 5, 2005

This issue of The Astrophysics Spectator continues the discussion of last issue on Keplerian orbits with the addition of a single page: a page containing an orbital simulator. The orbital simulator we present is a Java applet, so this page only works with browsers that are Java enabled. This is the first of many simulators that will be incorporated into these pages over the coming years.

The program has three pre-defined setups: a setup that shows the orbits of the five inner planets, a setup that shows five planets with the same semimajor axis but different eccentricities, and a setup that shows five planets with harmonic relationships between their periods.

But the simulator is more than an animation of pre-defined orbits: the parameters of the orbits can be varied by the reader, allowing him to examine a broad range of models.

The simulator is physically limited to the orbits of low mass planets in the Solar System. As a consequence, each planet travel on closed elliptical orbits that are independent of the mass of the planet's mass. In coming months I plan to add additional simulator pages for binary star systems, stars orbiting in the galactic plane, and bodies resonantly interacting with a planet as they move around the Sun.

New Simulator Page

Keplerian Orbit Simulator. This simulator page is part of the “ Gravitational Physics path.” Its body contains a simulator that shows how planets move around the Sun with time. The semimajor axis, eccentricity, and perihelion angle for an orbit can be varied by the reader. (continue)