Terms Used
Physics
Major science, dealing with the fundamental constituents of the universe, the forces they exert on one another, and the results produced by these forces.
Inertia
The property of matter that causes it to resist any change of its motion in either direction or speed.
Frame of reference
A set of geometric axes used to determine the location of a point in space
Inertial Frame of Reference
A coordinate system in which an object that has no net forces acting on it will move with constant velocity
Galaxy
A massive ensemble of hundreds of millions of stars, all gravitationally interacting, and orbiting about a common center. Astronomers estimate that there are about 125 billion galaxies in the universe.
Milky Way
The large, disk-shaped aggregation of stars, or galaxy, that includes the Sun and its solar system. In addition to the Sun, the Milky Way contains about 400 billion other stars.
