This Excel sheet will calculate the number of days between the current date and a date in the past since 1900. For example, the date of the first moon landing, 7/20/1969, can be entered to determine how many days ago this event occurred.
The sheet uses Julian dates, which is a dating system used in astronomy. The sheet converts an event given in month,day, and year to a single number. Julian dating allows the easy subtraction of dates to determine the length of time between two events.
Students can use the sheet to determine the number of days that they have lived by entering their own birth month, day, and year, or they can use if for historic events. The sheet also converts days into minutes and years.