Category:Astronomy in the 20th century BC
Astronomy by century: (BCE) 20th century · 19th century · 18th century · 17th century · 16th century · 15th century · 14th century · 12th century · 8th century · 6th century · 4th century · 3rd century · 2nd century · 1st century · (CE) 1st century · 7th century · 9th century · 11th century · 12th century · 13th century · 14th century · 15th century · 16th century · 17th century · 18th century · 19th century · 20th century · 21st century · 22nd century ·25th century ·Subcategories
This category has the following 9 subcategories, out of 9 total.