AST101H1 Lecture Notes - Lecture 7: Semi-Major And Semi-Minor Axes, Orbital Period

• School: UTSG
• Department: Astronomy & Astrophysics
• Course: AST101H1
• Professor: Eryan Apsnler, Michael Reid

Document Summary

Any object that has mass will bear a force of gravity. Any two mass-bearing objects will attract each other gravitationally. Example: the moon, despite bearing a gravitational force, does not attract greatly to earth as much as one would think because of the speed and direction of the moon"s travel (orbit) Orbit is achieved if an object travels along a circular trajectory fast enough to avoid intersecting the surface of an object within the circular perimeter formed. Free-fall: a state in which an object is moving solely under the influence of gravity. Speed determines the shape of an orbit. A minimum speed to achieve orbit will create an elliptic shape, while a faster speed will create a constant circle. There are speed thresholds for maintaining orbits. If an object travels fast enough, it will escape the gravitational influence of its host object, escaping orbit. Closed orbit = an orbit that completes to form a shape.