Geocentric vs Heliocentric Orbit Simulator

Heliocentric Perspective (Sun-Centered)

Inertial Reference Frame

Geocentric Observer Frame (Earth-Centered)

Apparent Trajectory & Retrograde

Earth Radius (AU) 1.00

Mars Orbit / Deferent Radius 1.52

Ptolemaic Epicycle Radius 0.40

Keplerian Eccentricity 0.09

Trace Length 300

Scrub Time:

Speed:

Real-Time Celestial Telemetry

Apparent Celestial Longitude 0.0°

Elongation Angle 0.0°

Apparent Motion State

DIRECT

Earth-Mars Distance 0.52 AU

[STATE: INITIALIZED] Mode: Copernican Mars | Longitude: 0.0° | Phase: DIRECT | Dist: 0.52 AU

Celestial Mechanics Insights: Apparent retrograde motion occurs when a planet appears to temporarily reverse its direction across the background stars. In the Copernican Heliocentric model, this loop is an optical illusion caused by Earth passing Mars on an inner, faster orbit. In the Ptolemaic Geocentric model, the same observed path is modeled by placing Mars on a secondary spinning circle (an epicycle) revolving along a primary deferent path around Earth.