What is an orbit and what determines its shape?

An orbit is the curved path of an object around a celestial body due to gravitational attraction. Orbital shape is determined by the object's velocity and direction relative to the gravitational field. A circular orbit requires velocity perpendicular to gravity with magnitude equal to circular velocity; elliptical orbits have varying velocity. Key orbital parameters include semi-major axis (size), eccentricity (shape from 0=circular to 1=parabolic), inclination (tilt relative to equator), and period (time for one revolution). Kepler's laws describe orbital motion: elliptical paths, equal areas in equal times, and period-radius relationship.