Hi,
I worked on the basis that if the day of a New Moon is counted as age 1,
the next one happens on the day with age 30 (the lunar month is 29 days,
so age 30 is the same as age 1). Thus finding New Moon in the desired
month can be achieved by finding the day with age 30, as follows:
- Take the Age value for the required calendar month from the table. For
December, the value is 10.
- Add the Epact, which for 2015 is also 10, making 20.
- To get our total up to 30 requires that a further 10 is added, which
is achieved by moving 10 days into December; December 1st plus 10 days
is December 11th.
This is same answer as Dave Bell derived, and I hope it wasn't just a
lucky fluke (was it?).
Steve
On 07/12/2015 19:46, Dave Bell wrote:
I admit it was tricky figuring out how to read the tables, but I
**think** I have it working for the current year.
December 3^rd (same day of week as January 1^st ) shows a lunar age of
10 days.
Adding the Gregorian epact of 10 (*), plus 4 days between the 3^rd and
today, gives an age of 24 days.
Next New Moon is December 11^th (**), 4 more days from now = 28 days
old, or New Moon.
Dave
(*) http://www.staff.science.uu.nl/~gent0113/easter/eastercalculator.htm
(**) http://www.moongiant.com/phase/12/9/2015
------------------------------------------------------------------------
*From:*sundial [mailto:[email protected]] *On Behalf Of
*graham stapleton
*Sent:* Monday, December 07, 2015 7:16 AM
*To:* [email protected]
*Subject:* Calculating age of the moon from the epact
Dear All,
The origin of my query is the seamen's boxes of Pieter Holm that
feature a table enabling a calculation from the epact - integers only
- of the (approximate) age of the moon.
Attempting to use the illustrated figures for the current year has
been unsuccesful and a general trawl of the web has not provided
anything that helps. A method applicable for any date would be ideal,
but at least for the first of the month. Thank you.
Using the Tables on the Seaman's Tobacco Box of Pieter Holm
<http://www.staff.science.uu.nl/%7Egent0113/holmbox/holmboxtables.htm>
<http://www.staff.science.uu.nl/%7Egent0113/holmbox/holmboxtables.htm>
---------------------------------------------------
https://lists.uni-koeln.de/mailman/listinfo/sundial
---------------------------------------------------
https://lists.uni-koeln.de/mailman/listinfo/sundial
