Comments on: Calculating the Moon Phase

By: blogger

blogger — Mon, 04 Jan 2010 22:02:32 +0000

I’ve tried calculating the illumination of the moon using Happy_2 and Anonymous’s suggestions. However, it’s hard to tell which one is more accurate, sometimes one seemed more accurate than the other. Not only that but many sites online differ by several percentage points themselves, so it’s hard to figure out which one is correct.

By: blogger

blogger — Wed, 24 Jun 2009 03:55:35 +0000

The code is in PHP and I cover how to get the longitude and latitude for the area you want. I’m sure it’s possible to implement it in Excel.

By: newbie

newbie — Mon, 22 Jun 2009 14:43:39 +0000

Hi there – I’m a bit (read: completely) new to this, so bear with me. I’m trying to calculate moon phases for East Africa (to see if phase of the moon affects hunting success of lions), and just came across your script. I was wondering what language it was in? Basically, I’m looking for something that I can implement in excel (that’s where I’ve got my data currently) – I was hoping to try to (learn to) write a macro so it would grab the date in one column and spit out the moon phase and % illumination in the next column.
So two questions: Is that something I can do with this code? and doesn’t moon phase depend on your location on the globe? (i.e. Would this algorithm be accurate for the US but not for Tanzania?)
Anyway, thanks for anything you can tell me!
Cheers

By: Anonymous

Anonymous — Mon, 08 Jun 2009 05:03:49 +0000

Just found this page – I’m going to try it out ..For illumination percentage
after $b = round($jd * 8);
how about

$percent=abs($b-8)*25

By: Happy_2

Happy_2 — Wed, 12 Nov 2008 21:27:24 +0000

I’ll try again, this time without the accidental markup.

Using the value of $jd after the line “$jd -= $b”, subtract $jd from 4 if $jd is less than 4, or from 8 if $jd is greater than 4. Divide the result by 4.

By: Happy_2

Happy_2 — Wed, 12 Nov 2008 21:22:11 +0000

I’m also grateful for the code. (Although that’s a lot of empty lines to delete after copy/paste. )

It looks to me like the percentage lit can be gotten this way: using the value of $jd after the line “$jd -= $b”, take the difference from 4 if $jd 4, and divide that difference by 4.

Thanks again.

By: Happy

Happy — Tue, 07 Oct 2008 02:20:10 +0000

Big THX for this code.

Until today, I have found functions and classes, which calculated moon-phase from 1970 year. That was too small range for me.

This script calculates correctly phase of the Moon and is so simple