Section 7 - Julian Dates

Manufacturing Corner on

Saturday, November 26, 2022

 It was Julius Caeser who first established the calendar based on 365 days per year with leap years, hence Julian dates. One of the reasons why spreadsheets are so good for scheduling is the way that they handle dates and times. All spreadsheets start counting time in days, and decimals of a day, from midnight before 1st January 1900, and there are enough decimal places of a day to measure time to the nearest 3 thousanth of a second!

This is the date and time according to the system clock in this computer, using the =NOW() function:

44884.8329608796   days since 1 January 1900

Keep hitting the F9 key to recalculate, and watch the clock change. Add 1 to it and you get the same time tomorrow. The really neat thing is that we only have one unit for  measuring time, a day. We don’t have to worry about seconds, minutes, hours, weeks, fortnights,  months, quarters, years, decades and centuries. However we can display the date and time in different  ways with Format Cells|Number|Date and Time.

Here are some different formats of NOW:

19:59:28

7:59:28 PM

7:59 PM

11/19

11/19/22

19-Nov

19-Nov-22

November-22

November 19, 2022

N-22

and by using =TEXT:

Sat

Saturday

Nov

November

2022

Take a look also at the date and time functions.

The spreadsheet takes care of the days in each month, and leap years etc.

Labels: Scheduling Excel Basic

Thanks for reading Section 7 - Julian Dates. Please share...!