ABSTRACT
Kepler's laws of planetary motion play a pivotal role in analyzing the two-body problem of the motion of an object orbiting another under the inverse- square- law gravitational force in astronomy and cosmology. It is well established that solar planets orbit the Sun in accordance with Kepler’s laws. The laws are also applicable to moons orbiting planets and spacecrafts orbiting the earth. This chapter gives a detailed account of the three laws of Kepler as applied to solar planets. It further extends the laws to exoplanets with rigorous equations. Worked out numerical example lends a feel for numbers associated with exoplanets. A mention of non-Keplerian dynamics is made at the end of the chapter, which is essential for tracing the history of dynamical evolution of exoplanets particularly with short orbital periods and hence highly eccentric orbits. Non-Kelperian treatment is necessitated while dealing with non-spherical exostars taking into consideration their radiation pressure and other perturbing factors.
