Keeping Time
LEARNING OBJECTIVES By the end of this section, you will be able to: The measurement of time is based on the rotation of Earth. Throughout most of human history, time has been reckoned by positions of the Sun and stars…
The Seasons
LEARNING OBJECTIVES By the end of this section, you will be able to: One of the fundamental facts of life at Earth’s midlatitudes, where most of this book’s readers live, is that there are significant variations in the heat we…
Earth and Sky
LEARNING OBJECTIVES By the end of this section, you will be able to: In order to create an accurate map, a mapmaker needs a way to uniquely and simply identify the location of all the major features on the map,…
Astronomy and the Poets
When Copernicus, Kepler, Galileo, and Newton formulated the fundamental rules that underlie everything in the physical world, they changed much more than the face of science. For some, they gave humanity the courage to let go of old superstitions and…
Gravity with More Than Two Bodies
LEARNING OBJECTIVES By the end of this section, you will be able to: Until now, we have considered the Sun and a planet (or a planet and one of its moons) as nothing more than a pair of bodies revolving…
Motions of Satellites and Spacecraft
LEARNING OBJECTIVES By the end of this section, you will be able to: Newton’s universal law of gravitation and Kepler’s laws describe the motions of Earth satellites and interplanetary spacecraft as well as the planets. Sputnik, the first artificial Earth satellite,…
Newton Universal Law of Gravitation
LEARNING OBJECTIVES By the end of this section, you will be able to: Newton’s laws of motion show that objects at rest will stay at rest and those in motion will continue moving uniformly in a straight line unless acted…
Newton’s Great Synthesis
LEARNING OBJECTIVES By the end of this section, you will be able to: It was the genius of Isaac Newton that found a conceptual framework that completely explained the observations and rules assembled by Galileo, Brahe, Kepler, and others. Newton was born…
The Laws of Planetary Motion
LEARNING OBJECTIVES By the end of this section, you will be able to: At about the time that Galileo was beginning his experiments with falling bodies, the efforts of two other scientists dramatically advanced our understanding of the motions of the planets.…
The Birth of Modern Astronomy
LEARNING OBJECTIVES By the end of this section, you will be able to: Astronomy made no major advances in strife-torn medieval Europe. The birth and expansion of Islam after the seventh century led to a flowering of Arabic and Jewish…