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How to compare Geocentric and Heliocentric models
Open the Geocentric vs Heliocentric 3D Explorer, toggle between the Ptolemaic (Earth-centered) and Copernican (Sun-centered) views of the same real Earth/Mars orbits, and read the live readout that reports whether Mars is in retrograde or direct motion.
- Open https://freetoolonline.com/space-3d/geocentric-vs-heliocentric.html and wait for the orbit rings to render.
- Press the Ptolemaic (Earth-centered) or Copernican (Sun-centered) toggle to switch views of the same underlying orbits.
- Drag the day slider (0-1559, two Mars synodic cycles of about 779.9 days each) or press Play to auto-advance time.
- Watch the live readout state whether Mars is currently retrograde (backward) or direct (normal eastward) apparent motion.
- In the Earth-centered view, follow the fading purple trail that traces Mars's recent apparent loop.
- Drag to orbit the camera, or scroll/pinch to zoom.
Geocentric vs Heliocentric key figures
| Milestone | Date |
|---|---|
| Ptolemy's Almagest (geocentric model, dominant ~1,400 years) | ~2nd century AD |
| Copernicus proposes heliocentrism | ~1515 |
| Copernicus publishes De revolutionibus | 1543 |
| Galileo observes Jupiter's four largest moons | 1610-01-07 |
| Newton's Principia | 1687 |
| Mars synodic period | about 779.9 days |
Next: the when guide or vs alternatives. Open the Geocentric vs Heliocentric 3D Explorer.
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