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
Reduced-gravity aircraft the final third not at all." Vomiting is referred to as "ill". Scopolamine is often used as an antiemetic during reduced-gravity-aircraft training. Reduced-gravity aircraft A reduced-gravity aircraft is a type of fixed-wing aircraft that provides brief near-weightless environments for training astronauts, conducting research and making gravity-free movie shots. Versions of such airplanes were operated by the NASA Reduced Gravity Research Program. The unofficial nickname "vomit comet" became popular among those who experienced their operation. Parabolic flight as a way of simulating weightlessness was first proposed by the German aerospace engineer Fritz Haber and the German physicist Heinz Haber in 1950.