Unit 2 Vocab

i dont have flashcards for the unit so i suggest you use this to go over it :)

retrograde motion

backward, westward loop traced out by a planet with respect to the fixed stars

Ptolemaic model

Geocentric solar system model, developed by the second century astronomer Claudius Ptolemy. It predicted with great accuracy the positions of the then known planets.

Heliocentric Model

Sun-centered model of the solar system

Ellipse

a figure like a elongated circle. Characteristics: degree of flatness, eccentricity, and length of its long axis

Astronomical Unit (AU)

Distance of Earth from sun. Precise radar measurements yield a value

Radar

Radio Detection and Ranging, Waves are bounced off an object, and the object the time taken for the echo to return is the distance

Weight

Gravitational force exerted on you by Earth (or planet)

Inertia

Tendency of an object to continue moving at the same speed and in the same direction, unless acted upon by a force

Coernican Revolution

Realisation, toward the end of the 16th century [Earth isn't centre of the universe]

Mass

Measure of total amount of matter contained within an object