Decades: 30s BC 20s BC 10s BC 0s BC 0s - 10s - 20s 30s 40s 50s 60s
Years: 14 15 16 17 18 - 19 - 20 21 22 23 24
Births
Deaths
... triangulate the distance to nearby stars from opposite sides of the Earth's orbit. This is traditional astrometry. Another was the use of Cepheid variable stars to ...