Certainly Kepler " coat of the sleeve " this first law of speed thanks to one surprises intuition. Quickly stowed by its successors, on the forces that would have to govern a solar universe, on the other hand this primitive statement of the law of speeds is not total correct mind, the law of the areas denominated the second law of Kepler. He is not absolutely equivalent to which relates speeds and distances inversely. Being something but necessary the results deduced from first of them, despite when they are used in the calculation of the planetary positions. Both formulations of the law of speeds, lead to almost identical forecasts, Kepler believed. Wrongly, in the equivalence of both laws. For more information see this site: Sela Ward. Using them indifferently throughout all their life.

Despite his visionary and little orthodox resonances, the primitive statement, neoplatonic of the law of speeds, I reveal myself essentially in but the fecund investigations of Kepler, unlike when it makes reference to its deduction of the law of speeds, the work of Kepler on the elliptical orbits glass completely in but the meticulous and complete study of the best astronomical observations available. It tried, one after another series of orbits. Leaving them after laborious calculations showed their discord with the data collected by Brahe, the scrupulous attempts of Kepler to fit to their theoretical orbits to the data objectives which it had mention quite often like one of the first examples of the scientific method par excellence. Despite either the law of the elliptical orbits. Well-known under the name of first law of Kepler, exclusively it was extracted of the observation and the calculation. Unless one assumes that the planetary orbits are closed on themselves. (knowledge acquired at time subsequent to the one of Kepler) one is needed law of speeds to be able to at first calculate the form of those from data collected by observation, to if then when it analyzed the observations of Brahe, Kepler were making use constant of its primitive Neoplatonicas intuitions.