How to Change the Date and Time
There are two ways to change the date and time for which the Sky Chart shows the sky. First, from the Combined View (the dual-pane screen with the circular chart on the right and the rectangular window at upper left), click the CHANGE button in the Date & Time display area at the lower left of the screen. This will take you to the Choose Date & Time page:
Use the this screen to set the date and time for which the Sky Chart shows you the visible sky. This is also where you tell the applet whether to use daylight saving time.
Choose any date between 1 January 1600 and 31 December 2400 using the day and month pull-down lists and the year text-entry box. If daylight saving time was, is, or will be active for your current observing location on your selected date, check the small box to the right of the words Daylight Saving Time. If you wish to change your location and time zone, use the link supplied.
If you want the Sky Chart to use Universal Time (UT) rather than local time, check the small box provided for that purpose. UT, which is essentially the same as Greenwich Mean Time, is used worldwide by astronomers and others to avoid confusion between time zones.
With the date and time controls in the Combined View, you can step backward or forward in time just highlight the field you want and click the + or button.
The second way to change the Sky Chart's date and time is to click on the month, day, year, hour, or minute in the display at lower left in the Combined View (under the Date & Time heading), which will become highlighted (in the following example, the hour field has been selected):
Then use the + or button to increase or decrease the value you've selected. Each time you change a quantity, both the Selected View and All-Sky Chart will be updated instantly.