Chapter 3

Question 1

Model

Answer 1

a representation of some aspect of nature that can be used to explain and predict real phenomena without invoking myth, magic, or the supernatural

Question 2

Perihelion

Answer 2

the point at which an object orbiting the Sun is closest to the Sun

Question 3

Theory

Answer 3

See A model of some aspect of nature that has been rigorously tested and has passed all tests to date

Question 4

Focus

Answer 4

the point at which rays of light that were initially parallel converge

Question 5

Geocentric model

Answer 5

any of the ancient Greek models that were used to predict planetary positions under the assumption that Earth lay in the center of the universe

Question 6

Foci

Answer 6

plural of focus

Question 7

Kepler’s laws of planetary motion

Answer 7

three laws discovered by Kepler that describe the motion of the planets around the Sun

Question 8

Paradigm

Answer 8

a general pattern of thought that tends to shape scientific study during a particular time period

Question 9

Ellipse

Answer 9

a type of oval that happens to be the shape of bound orbits

Question 10

Ptolemaic model

Answer 10

the geocentric model of the universe developed by Ptolemy in about 150 A.D.

Question 11

Semimajor axis

Answer 11

half the distance across the long axis of an ellipse, it is usually referred to as the average distance of an orbiting object

Question 12

Copernican revolution

Answer 12

the dramatic change, that occurred when we learned that Earth is a planet orbiting the Sun rather than the center of the universe

Question 13

Aphelion

Answer 13

the point at which an object orbiting the Sun is farthest from the Sun

Question 14

Hypothesis

Answer 14

a tentative model proposed to explain some set of observed facts, but which has not yet been rigorously tested and confirmed

Question 15

Eccentricity

Answer 15

a measure of how much an ellipse deviates from a perfect circle