Newton's Law of Gravity

Chapter index in this window —   — Chapter index in separate window

This material (including images) is copyrighted!. See my copyright notice for fair use practices. Select the photographs to display the original source in another window.

Isaac NewtonThis chapter covers the revolutionary advancements due to probably the most brilliant scientist who ever lived: Isaac Newton (lived 1641--1727). His greatest contributions were in all branches of physics. Kepler's discoveries about elliptical orbits and the planets' non-uniform speeds made it impossible to maintain the idea of planetary motion as a natural one requiring no explanation. Newton had to answer some basic questions: What keeps the planets in their elliptical orbits? On our spinning Earth what prevents objects from flying away when they are thrown in the air? What keeps you from being hurled off the spinning Earth? Newton's answer was that a fundamental force called ``gravity'' operating between all objects made them move the way they do.

Newton developed some basic rules governing the motion of all objects. He used these laws and Kepler's laws to derive his unifying Law of Gravity. I will first discuss his three laws of motion and then discuss gravity. Finally, several applications in astronomy will be given. This chapter uses several math concepts that are reviewed in the mathematics review appendix. If your math skills are rusty, study the mathematics review appendix and don't hesitate to ask your astronomy instructor for help. The vocabulary terms are in boldface.

I include images of world atlases from different time periods in this chapter and the previous one as another way to illustrate the advances in our understanding of our world and the universe. Links to the sites from which the photographs came are embedded in the images. Select the picture to go to the site (will display in another window).

World map at time of Newton
Nova orbis tabula [De Wit 1688]. Select the image to go to the Hargrett Library at the Univ. of Georgia from which this picture came. Note the curved path of the Sun between the Tropic of Cancer (at latitude 23.5° N) and the Tropic of Capricorn (at latitude 23.5° S).

next Go to next section

Go to Astronomy Notes home

last updated: January 5, 2015

Is this page a copy of Strobel's Astronomy Notes?

Author of original content: Nick Strobel