Explore how star mass, initial distance, and velocity affect a planet's orbit. Discover the relationship between orbital period and semi-major axis.
| Mass (M) | a (AU) | T (Yr) | a³ | T² | e |
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In the early 17th century, the German astronomer Johannes Kepler inherited an unparalleled dataset of planetary observations from his mentor, Tycho Brahe. Before this time, astronomical models generally relied on circular orbits—a paradigm that traced back to ancient Greek philosophy and was present in both the Ptolemaic geocentric model and the Copernican heliocentric model. However, the precise measurements recorded by Brahe, particularly of Mars, could not be reconciled with perfectly circular paths.
Kepler's meticulous analysis of this data led to a profound paradigm shift in our understanding of celestial mechanics. He formulated three fundamental principles that govern planetary motion. These principles broke away from the assumption of uniform circular motion, instead demonstrating that orbits follow different geometries and that orbital speeds vary depending on a planet's distance from its star. Kepler's work established a mathematical foundation that later enabled Isaac Newton to formulate his universal law of gravitation, unifying the physics of the heavens with the physics of the Earth.
This simulation focuses on the mechanics of orbital systems. By manipulating the mass of the central star, the initial distance of the orbiting body, and its initial velocity, you can observe how these variables influence the resulting orbital trajectory. The simulation allows you to explore various orbital shapes—from circular to highly eccentric ellipses—and gather data to investigate the fundamental mathematical relationships that describe orbital periods and distances.