On Wed, 25 Mar 2009 19:57:21 -0500, Chuck wrote:

Is there an equation that will calculate the phases of the moon?

Chuck
Bernie,

If you are still watching the thread, I found a listing of Blue Moons (second
full moon in a month)

Subtracting the first date/time value from the second should give the time for
one lunar cycle. The list has 9 Blue Moons. The longest cycle was 29.73750000
days (10/1/2020 21:05 to 10/31/2020 14:47) GT. The shortest cycle was
29.29583333 days (8/1/2023 18:29 to 8/31/2023 1:35). The difference in cycle
time is 10 hrs 36 mins. That is a huge cycle time variation. Can this
possibly be? No two months had the same cycle time. Makes me wonder about the
accuracy of the source data.

From "Pictorial Astronomy" by Alter, Cleminshaw, and Philips 1966 synodic month
= 29d, 12h, 44m, 2.8s. (29.53058796 days).

Chuck