Physics

# Key Terms

PhysicsKey Terms
aphelion
closest distance between a planet and the sun (called apoapsis for other celestial bodies)
Copernican model
the model of the solar system where the sun is at the center of the solar system and all the planets orbit around it; this is also called the heliocentric model
eccentricity
a measure of the separation of the foci of an ellipse
Einstein’s theory of general relativity
the theory that gravitational force results from the bending of spacetime by an object’s mass
gravitational constant
the proportionality constant in Newton’s law of universal gravitation
Kepler’s laws of planetary motion
three laws derived by Johannes Kepler that describe the properties of all orbiting satellites
Newton’s universal law of gravitation
states that gravitational force between two objects is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.
perihelion
farthest distance between a planet and the sun (called periapsis for other celestial bodies)
Ptolemaic model
the model of the solar system where Earth is at the center of the solar system and the sun and all the planets orbit around it; this is also called the geocentric model