How to enter a moon phase series into Excel??

[Michael Levin]

I'm a biologist working with some circadian rhythm data. I need to be able
to make a chart in excel where the X axis is dates, with correct phases of
the moon for each phase. What is the easiest way to get moon phase series
into an excel sheet?

 

[macropod]

Hi Michael,

For your purposes, you can approximate the phase of the moon using a formula
like:
=COS(RADIANS(360/29.530588*(ROW()-1+n)))
where a starting date at the full moon is on row 1 and 'n' is the expired
proportion of the day when the full moon occurred (eg 1am = 0.041667, 12
noon = 0.5). Then copy down for as many rows as needed. If you chart this
against the dates, you'll see a sine wave, where 1s are full moons -1s are
new moons and 0s are half-moons. If your starting time & date start on a row
other than row 1, change the '1' in the formula to match.

You will note that I said 'approximate'. That is because lunar cycles are
not exactly 29.530588 days each, but only average something close to that
value.

Cheers