The Earliest Copernicans
Major Figures of the Scientific Revolution
Nicolas Copernicus (1473-1543) Astronomical Background. Ptolemaic astronomy, within the general framework of Aristotelian physics, dominated contemporary astronomical thought–a mathematical, non-observational approach concerned with ‘saving the phenomena’. Basic premises of ancient astronomy: Geostatic and geocentric cosmos. Celestial bodies possess uniform, circular motion around a central point. Celestial bodies are composed of a fifth element, the quintessence. […]
Galileo’s Major Works
Galileo Measures the ‘Mountains on the Moon’
Kepler’s Major Works
Kepler’s Planetary Laws – So-Called
1st Law (1609): Each planet (P) revolves around the Sun in an elliptical orbit, with the Sun at one focus of the ellipse. 2nd Law (1609): A radius vector from the Sun to any particular planet sweeps out equal areas in equal times. (The hatched-in areas are equal.) 3rd Law (1618): The squares of the […]
Conic Sections – Sections of a Cone
Studied since the time of Plato’s Academy, conic sections (sections of a cone: circles, ellipses, parabolas, hyperbolas) were brought to force during the Scientific Revolution to describe planetary paths and projectile trajectories. Apollonius of Perga (3rd century B.C.) was the first to treat conics rigorously, and his work was the basis of several of Newton’s […]
Kepler’s Equant and Vicarious Hypotheses
Kepler’s equant law suggests that if a planet sweeps out equal angles in equal times with respect to the kenofocus (empty focus F), it will pass through arcs AB and CD in equals times, since angles alpha and beta are equal. Hence a given planet moves faster along arc AB (perihelion) than arc CD (aphelion). […]