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
Planetary nebula Planetary nebula A planetary nebula, abbreviated as PN or plural PNe, is a type of emission nebula consisting of an expanding, glowing shell of ionized gas ejected from red giant stars late in their lives. The term "planetary nebula" is arguably a misnomer, since this phenomenon is not associated with observations of actual planets, and perhaps was derived from the planet-like round shape of these nebulae as observed by astronomers through early telescopes. The term may have originated in the 1780s with the English astronomer William Herschel who described these nebulae as resembling planets; however, as early as January 1779,