The current date is autamtically detected from your device and updates in real time. You can also calculate the length of time between two dates by tapping on the date area at the top of the screen. Choose a start and end date and time to see the length of time between this date range shown below. Once you have calculated a date, you can quickly add this even to your calendar without having to leave the app. * The position of the sun and moon are for design purposes only and should not be relied upon as being accurate. *