1. A History of Astronomy
Ptolemy
( AD )
geocentric theory

2. Nicolas Copernicus
( 1473 – 1543 )
heliocentric theory

3. Galileo Galilea ( 1564 – 1642 ) invented telescope
discovered moons of Jupiter

4. Tycho Brahe
( 1546 – 1601 )
plotted orbit of Mars

5. Johannes Kepler
( 1571 – 1630 )
Three Laws of
Planetary Motion

6. Isaac Newton
( 1643 – 1727 )
Discovered Law of Universal Gravitation

7. Law of Universal Gravitation:
The attractive force between two objects is:
-directly proportional to the product of the masses
-inversely proportional to the square of the distance
between them