NewMoon

New Moon Calculator

This page runs a Javascript program which takes the current time and date, calculates the approximate time and date of the last previous and next new Moon. And there is more.

You can enter a date in the boxes at the right and click the Calculate button. The program will calculate the date and time (plus minus a few minutes for dates from 2000 B.C. to 2100 A.D.) of the New Moon close to the date you enter. ClearEntries before you enter a new date.

Year = Month = Day =

The New Moon close to this date is:
Year = Month = Day =
Approximate time:hoursminutes U.T.

Astronomers use a dating system which include the year zero and years before zero are negative while those after are positive. Historians use a dating system where there is no zero year and there is a B.C. and A.D. Thus, the year "0" here corresponds to "1 B.C.", and the year "-100" is "101 B.C.", etc..

This calculation is performed using an algrorithm found in Astronomical Algorithms, 2nd edition by Jean Meeus, December 1998,Willmann-Bell, ISBN: 0943396611.

If you would like to compare this calculation with slightly more accurate calculations of the phases
of the Moon you can consult the Five Millennia Catalog of Phases of the Moon compiled by
NASA's Fred Espenak.

The animated gif of the phases of the moon was made by Ed Stephan using photographs from the U.S. Naval Observatory.

This page prepared by C.Hartley, Director of the Ernest B. Wright Observatory at the Department of Physics at Hartwick College in the City of Oneonta, NY. More things from C. Hartley at his home.