Warning: the performance of this simulation may vary from one system to another. Please see the description of the Extra Options Menu below for information on how to achieve the best performance on your computer.

Celestial Globe


General Description

This program simulates the Two Sphere Universe theory of the Ancient Greeks. This theory supposes the stars to be fixed on the suface of a Celestial Sphere, with the spherical Earth at the center of this sphere. The simulation shows the motion of Sun and stars in this model, as well as the horizon plane for an observer on the spherical Earth. Two views are shown: one from outside the Celestial Sphere, and the other from the point of view of an observer on Earth looking up. Most of the characteristics of the simulation can be adjusted, including the latitude of the observer, the time of day, the time of year, the period of Sun's motion, the tilt of Earth's rotational axis relative to the ecliptic plane,and the eccentricity of Earth's orbit. You can also change the calendar year (the default is 2000 AD) to see the precession of the equinoxes.

The program simulates the motion of the true Sun which does not move through the stars at a uniform rate because of Earth's elliptical orbit. A menu option changes the simulation to use a Sun that moves uniformly along the ecliptic.


Celestial Globe Frame


Sky View Frame


Controls


Additional Controls

Note that these controls are hidden by default. Select "Display Additional Controls" from the Extra Options menu in the Celestial Globe frame to see these controls.

Version History


Todd K. Timberlake (ttimberlake@berry.edu)