You can use RedShift to simulate astronomical events that took place in the past, or are forecast to take place at some time in the future. You can enter a new time and date using the Time panel.   Use the pop-up menu to select Local time, Universal time or Julian date format. Local time on Earth depends on the longitude of your current location, so astronomers normally specify the time of an event using Universal Time. Universal Time is the current time at the prime meridian (0 degrees longitude) without daylight saving applied. If you have chosen a location away from the Earth's surface you may only specify time as Universal Time. Each time you run RedShift it calculates the current Universal Time according to the time and date set on your computer (system time). Refer to section Customising RedShift to understand more about how this is done. The correct position of the stars and planets are calculated using your system's time and date so - if you wish to use RedShift's real time feature - it is important that these are correctly set. RedShift also lets you work using the Julian date. The Julian date is the number of days which have elapsed since noon at Greenwich on the 1st of January 4713 BC.   RedShift 3 lets you set the date anywhere between 4712 BC and 9999 AD. RedShift automatically adjusts the epoch for the time set in the Time panel so as to allow for the effects of precession. The box contain field can be edited. Each value in the box operates as a separate field (e.g. - month, day and year). Click a value in a field to highlight it. Use the keyboard to enter new values, press return/enter to apply the new values immediately. Otherwise the new values will be applied when some other change is applied to the sky window. Use pop-up menu indicated by a down arrow button at the right of the box to select from frequently used settings. Press the letter "b" or "a" to change between "AD" and "BC" in the date field.   Use the Date pop-up menu using this button to select from frequently used settings.   The local time zone for the present RedShift location is displayed in this field (only when local time display is selected).   Select 12 hour or 24 hour clock format using Preferences (File menu, Preferences...). The box contain field can be edited. Each value in the box operates as a separate field (e.g. - hours, minutes). Click a value in a field to highlight it. Use the keyboard to enter new values, press return/enter to apply the new values immediately. Otherwise the new values will be applied when some other change is applied to the sky window. Use pop-up menu indicated by a down arrow button at the right of the box to select from frequently used settings. Press the letter "p" or "a" to change between "am" and "pm" in the time field.   Use the Time pop-up menu using this button to select from frequently used settings.