handbook of satellite orbits from kepler to gps Johannes Kepler (/ˈkɛplər/;[1] German: [joˈhanəs ˈkɛplɐ, -nɛs -];[2][3] December 27, 1571 – November 15, 1630) was a German astronomer, mathematician, and astrologer. He is a key figure in the 17th-cent