The Moonstick

A moonstick is a slide rule moon phase calendar.  It replaces a conventional moon phase chart or moon phase calculator.  The moonstick can determine the moon phase for any date, past (8000 years), present, or future (8000 years).  It can also perform a variety of "advanced searches" (for example, "On what dates this year are there new moons?  How long until there is a full moon on Halloween?").  The moonstick automatically recognizes all leap years and leap centuries, all time zones, the calendar adjustment of 1582, and years "BC".  The moonstick produces results accurate to 1½ hours in approximately 10 seconds. More...