Alternative Solar Systems

Sorry, you need Java to view this simulation


1) This applet allows you to examine and compare the early solar system models of Ptolemy, Copernicus, and Brahe. For each model, the "View from Above" panel displays a view of the entire solar system (as was known in Tycho Brahe's time).The "View from Earth" panel displays the planets' positions against the background constellations of the zodiac as predicted by the model (solid circles) and as actually observed (open circles). Click on the "Model" button to cycle through the three models.

2) For each model, you can view the orbits (white lines), planetary paths, or just the planets (plus the Sun and Moon), by clicking the "Paths" button.

3) The "Reset Time" button resets the model to UT 2000 Jan 1 12:00:00. The models have been adjusted to be as accurate as possible at that time (given the uncertainies in resolution).

4) Use checkboxes (Seconds, Minutes, etc) to choose time interval. "Days" works best for animation. Use slidebar at right to control simulation speed. There are 7 speeds, 3 forward (right), 3 reverse (left) and one neutral (center), although depending on your computer speed, there may be no difference between the two faster speeds. The bar is initially set at the slowest forward speed. Use "Reset Time" to return to present.

5) Careful examination will reveal that the "View from Above" and "View from Earth" panels do not exactly agree. The View from Earth is the more accurate view. The View from Above has been modified somewhat so that the orbits of the inner planets are clearly visible.

6) There is still a problem with the local time - it does not take into account the shift to/from Daylight Savings Time, and so may be off by an hour. Universal Time will always be correct.

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October, 2012