# Kepler-s-laws sentence example

kepler-s-laws

- It is quite evident that Kepler's laws do not in themselves enable us to determine the actual motion of the planets.
- He quotes as an instance that Newton in this way added to the planetary appearances contained in Kepler's laws the gravitation of the planets to the sun, as a notion of causality not contained in the appearances, and thus discovered that gravitation is the cause of the appearances.
- Newton did indeed first show synthetically what kind of motions by mechanical laws have their ground in a centripetal force varying inversely as the square of the distance (all P is M); but his next step was, not to deduce synthetically the planetary motions, but to make a new start from the planetary motions as facts established by Kepler's laws and as examples of the kind of motions in question (all S is P); and then, by combining these two premises, one mechanical and the other astronomical, he analytically deduced that these facts of planetary motion have their ground in a centripetal force varying inversely as the squares of the distances of the planets from the sun (all S is M).
- Conversely, assuming this law of attraction, it can be shown that the planets will move according to Kepler's laws.
- Having these data, the position of the planet at any other time may be geometrically constructed by Kepler's laws.Advertisement
- The announcement of the third of " Kepler's Laws " was made ten years later, in De Harmonice Mundi.
- If the law of attraction is that of gravitation, the orbit is a conic section - ellipse, parabola or hyperbola - having the centre of attraction in one of its foci; and the motion takes place in accordance with Kepler's laws (see Astronomy).