EarthOrbit


General Description

This simulation illustrates the Copernican theory of Earth's orbit around the sun. The top window shows a view from outside the celestial sphere. The simulation shows the moving Earth along with its axis or rotation and the line of sight from Earth, through Sun, to the Celestial Sphere. The end of the arrow indicates where, on the Celestial Sphere, Sun appears to be located as seen from Earth. The tilt of Earth's rotational axis (relative to the ecliptic plane) is adjustable. The bottom window shows the view of a portion of the sky (near the ecliptic) as seen by an observer on Earth.

Note that this simulation also illustrates Copernicus' theory of the seasons, since the North pole of Earth alternately tilts toward or away from the sun as the Earth travels through its orbit. A menu allows the user to position the Earth for the solstices/equinoxes.

Finally, the simulation can illustrate one of the major problems for the Copernican system: the problem of parallax. If Earth orbits Sun then the celestial poles should trace out circles through the stars over the course of each year. The simulation will trace the motion of the celestial poles to illustrate this parallax effect, and by reducing the radius of Earth's orbit the user can see how Copernicus explained why no annual motion of the poles had ever been observed.


Orbit Frame


Sky View Window


Todd K. Timberlake (ttimberlake@berry.edu)