Kepler Laws: Introduction to Astrophysics

This lecture introduces the Kepler Laws, which describe the motion of planets around the Sun. The three laws state that planets move in elliptical orbits with the Sun at one focus, sweep out equal areas in equal times, and have orbital periods related to the semi-major axis. The concept of orbital planes and the law of areas are also discussed, emphasizing the relationship between the radius vector and the area swept by it. Furthermore, the lecture covers the concept of reduced mass and its application in the third Kepler Law, highlighting the relationship between the masses of celestial bodies and their distances. The lecture concludes by explaining that the orbital period of a planet is independent of its eccentricity.