The Julian calendar

In response to the mismanagement of the calendar by the authorities of the day, Julius Caesar, with advice from Alexandrian astronomer Sosigenes, made changes to the existing Roman calendar to produce:
The Months
The Days

Januarius
Februarius
Martius
Aprilis
Maius
Junius
31
28/9
31
30
31
30


Julius*
Sextilius
September
October
November
December

*Originally Quintilis
31
30
31
30
31
30		        Then
Saturn’s Day
Sun’s Day
Moon’s Day
Mar’s Day
Mercury’s Day
Jupiter’s Day
Venus’s Day		      Now
Saturday
Sunday
Monday
Tuesday
Wednesday
Thursday
Friday