Timeline of Solar system By Jeffrey Liang Period: 100 to 160 Claudius Ptolemy Period: Feb 19, 1473 to May 21, 1543 Nicolaus Copernicus Period: Feb 15, 1564 to Jan 8, 1642 Galileo Galilei Period: Dec 27, 1571 to Nov 15, 1630 Johannes Kepler Period: Nov 8, 1656 to Jan 14, 1742 Edmond Halley Period: Nov 15, 1738 to Aug 25, 1822 William Herschel Period: 1801 to 1807 Discovery of the first four asteroids Period: Mar 11, 1811 to Sep 23, 1877 Urbain Le Verrier Period: Feb 4, 1906 to Jan 17, 1997 Clyde Tombaugh Period: Aug 20, 1977 to Sep 5, 1977 Voyagers 1 and 2