Kepler's laws of planetary motion formula_16 The area enclosed by the elliptical orbit is formula_17 So the period formula_18 satisfies and the mean motion of the planet around the Sun satisfies This captures the relationship between the distance of planets from the Sun, and their orbital periods. Kepler enunciated in 1619 this third law in a laborious attempt to determine what he viewed as the "music of the spheres" according to precise laws, and express it in terms of musical notation. So it was known as the "harmonic law". Using Newton's Law of gravitation (published 1687), this relation can be found in the case of
Clarke's three laws same time. Clarke's first law was proposed in the 1962 edition of the essay, as "Clarke's Law" in "Profiles of the Future". The second law is offered as a simple observation in the same essay but its status as Clarke's second law was conferred by others. It was initially a derivative of the first law and formally became Clarke's second law where the author proposed the third law in the 1973 revision of "Profiles of the Future," which included an acknowledgement"." It was also here that Clarke wrote about the third law in these words: "As three laws were good