Kepler orbit led to Johannes Kepler working on his celestial mechanics. He later became known as the father of calculus. In 1601, Johannes Kepler acquired the extensive, meticulous observations of the planets made by Tycho Brahe. Kepler would spend the next five years trying to fit the observations of the planet Mars to various curves. In 1609, Kepler published the first two of his three laws of planetary motion. The first law states: More generally, the path of an object undergoing Keplerian motion may also follow a parabola or a hyperbola, which, along with ellipses, belong to a group of curves known
Stellar triangulation worldwide, and is now a permanent service of IUGG and IERS. The photographic observations as done 1959–1985 are irrelevant now because of their expense, but lead to some renaissance by electro-optical techniques like CCD. Stellar triangulation Stellar triangulation is a method of geodesy which uses cosmic instead of terrestrial targets. It was first done by the Finnish geodesist Väisälä in 1959, who made astrometric photographs of the sky at two stations together with a balloon probe between them. Even this first step showed the potential of the method, because Väisälä got the azimuth between Helsinki and Turku (a distance of