The Beginning?
Period: Between 13 and 20 billion years ago
Lunar and Solar calendars
Period: About 2000 B.C.
Aristarchus of Samos
Period: About 280 B.C.
Armillary Sphere
Period: From 813 A.D. to 833 A.D.
Mural Sextant
Period: 994 A.D.
Nicolaus Copernicus
Period: 1543 A.D.
Hans Lippershey Telescope
Period: 1609 A.D.
Galileo Telescope
Period: 1609 A.D.
Cassini and Mars
Period: 1666 A.D.
Halley's Comet
Period: 1705 A.D.
Doppler Effect
Period: 1842 A.D.
Robert Kirchhoff's Spectrum Analysis
Period: 1860-63 A.D.
Mount Wilson Observatory
Period: 1905 A.D.
Hubble Law
Period: 1923 A.D.
Constellation Sagittarius
Period: 1927 A.D.
Cosmic Radio Waves
Period: 1933 A.D.
Grote Reber
Period: 1937 A.D.
Sputnik
Period: 1957 A.D.
Yuri Gagarin
Period: 1961 A.D.
Apollo 11
Period: 1969 A.D.
Venera 7
Period: 1970 A.D.
Vikings
Period: 1976 A.D.
Hubble Space Telescope
Period: 1990 A.D.
Cassini-Huygens
Period: 1997 A.D.
NEAR spacecraft
Period: 2001 A.D.
